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1
Stephens, R. J. "Aromatic nitrations using dinitrogen pentoxide". Thesis, University of Exeter, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370935.
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Karriem, Fatiema. "Oxidative fixation of dinitrogen by photocatalysis". Thesis, University of Western Cape, 2000. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_5777_1267648612.
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The heterogeneous photocatalytic oxidation of dinitrogen to nitrate, NO3 and/or nitrite, no2 using peroxy species of titanium (IV) in aqueous suspensions has been investigated. The photocatalysts used were titanium peroxide and Degussa p25 TiO2 pretreated with H2O2. These photocatalysts were investigated by SEM and FTIR spectroscopy.
3
Park, Rosa. "Investigating new reactions for coordinated dinitrogen". Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2344.
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The chemistry of the tantalum dinitrogen complex ([NPN]Ta)₂(μ-H)₂(μ-η¹:η²-N₂)Ta-[NPN], 1, (where [NPN] represents the acyclic tridentate ligand [(PhNSiMe₂CH₂)₂-PPh]²-), with primary alkenes, group IV and V metallocene complexes, and GaCp* is explored.
The reaction of 1 with 1-pentene and 1-hexene occurs via olefin-insertion into the metal-hydride bond to give two new complexes, ([NPN]Ta(CH₂)₄CH₃)₂(μ-η¹:η¹-N₂), 10, and ([NPN]Ta(CH₂)₅CH₃)₂(μ-η¹:η¹-N₂), 11, which were characterized using NMR spectroscopy. The solid-state structure of 11 was established and revealed that N₂ has been transformed into a bridging end-on mode. In contrast to its G symmetry in solution, the solid-state structure of 11 is C, symmetric; a VT-NMR study was performed and showed that 11 exists as an equilibrium between two isomers in solution: a C, symmetric isomer 11A,which is the predominant isomer at room temperature, and a C, symmetric isomer 11B,which is the minor isomer.
The reactivity of 1 with group IV and V metallocenes was investigated. The reaction of 1 with Cp₂Hf(PMe₃)(η²-Me₃SiCCSiMe₃) produces [N(μ-P=N)N]Ta(μ-H)₂(μ-N(Hf-Cp₂))Ta[NPN], 14, in which N₂ is cleaved and new Hf-N and P=N bonds have formed. The reaction of 1 with group V metallocene hydrides Cp₂MH₃ (M Nb, Ta) was also attempted however these complexes do not react with 1.
The reaction of 1 with GaCp* produces a new complex, [NPN]Ta(μ-N(GaCp*))Ta(=NPμ)[NPIA,-N], 18, which was characterized using NMR spectroscopy. Complex 18 decomposes over several days in solution, and one product of decomposition that was isolated was [(PhNH)(NPμ-N)Ta]₂, 19. The solid-state structure of 19 showed that the [NPN] ligand was cleaved at the N-Si bond, similar to that observed for the reaction of 1 with 9-BBN and HB(C₆H₅)₂. A mechanism for the formation of complexes 18 and 19 is proposed.
4
Dormer, Jonathan Charles. "Nitrations and oxidations with dinitrogen pentoxide". Thesis, University of Exeter, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385700.
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Chan, Sam Yun Fu. "Extended-chain complexes of dinitrogen-based ligands". Thesis, University of Reading, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408160.
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Sanderson, A. J. "Nitration with dinitrogen pentoxide in nitric acid". Thesis, University of Exeter, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.232979.
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Bultitude, John. "Vanadium complexes in relation to dinitrogen fixation". Thesis, University of Surrey, 1987. http://epubs.surrey.ac.uk/847178/.
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The aim of this work was to investigate the chemistry of vanadium in relation to dinitrogen fixation and consequently the literature concerning vanadium systems which reduce dinitrogen in protic media and the coordination compounds of vanadium(II) and vanadium(III) has been surveyed. In view of the importance of tertiary phosphines in the stabilisation of dinitrogen complexes of second and third row transition metals, methyldiphenylphosphine complexes of vanadium(III), (VCl3(PPh2Me)2) and (VCl3(MeCN) (PPh2Me)2) have been prepared and their electronic spectra and magnetic moments measured. The structures, determined by single crystal X-ray diffraction methods, are trigonal bipyramidal, (VCl3(PPh2Me)2), and octahedral, (VCl3(MeCN) (PPH2Me)2), with the phosphines occupying axial positions in both complexes. Attempts to reduce these complexes did not give any products reactive towards dinitrogen. Hydrated vanadium(II) salts (V(H2O)6)SO4, trans-(V(H2O)4Cl2), and (V(H2O)6)Br2 , were prepared by electrolytic reduction of the corresponding vanadyl solutions for use in the preparation of more reactive vanadium(II) complexes. (V(MeOH)6)Br2 was prepared from the hydrate and used to prepare (VBr2(thf)2) which was used in turn to prepare (VBr2(dppe)2). The diffuse reflectance spectra and magnetic moments of these complexes are consistent with octahedral stereochemistries throughout. The tetrahydrofuran complex is thought to be a bromide-bridged polymer and the phosphine complex is thought to be trans-(VBr2(dppe)2).
8
Smith, Steven Escar. "Satellite measurements of dinitrogen pentoxide in the stratosphere". Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337541.
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Doyle, Laurence. "Dinitrogen activation and reduction with iron phosphine complexes". Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/51149.
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The conversion of dinitrogen to ammonia is a fundamental process for sustaining life on our planet. Ammonia provides a source of fixed nitrogen for nitrification and assimilation into plants, and is the ultimate source of almost all nitrogenated compounds. Synthetic ammonia is produced on a colossal scale by the Haber Bosch process, with an annual ammonia output exceeding 130 million tonnes. However, the intensive operating conditions of this process require a staggering energy cost; hence, the development of a lower energy solution is recognised as one of the major challenges of modern chemistry. This dissertation explores the chemistry of homogeneous systems based on iron diphosphine complexes that are able to transform coordinated dinitrogen into ammonia. A greater understanding of these systems may provide insight into the iron-based catalysts utilised in both biological nitrogen fixation and the industrial Haber Bosch process. Ultimately, this could lead to a more sustainable process for meeting the global requirement for fixed nitrogen. Chapter 1 provides a general introduction into dinitrogen fixation chemistry, with a particular focus on homogeneous systems involving iron. Chapter 2 describes a convenient synthetic protocol to 1,2-bis(dialkylphosphino)ethanes. These are among the most versatile ligands used in inorganic chemistry, although issues with prior syntheses, often involving extremely hazardous phosphine precursors, has limited their accessibility. Chapter 3 is an exploration of a seminal work on dinitrogen fixation involving iron complexes, which facilitate the conversion of coordinated dinitrogen to ammonia in what is known as the Leigh cycle. Mechanistic understanding of the key ammonia producing step has provided the focus of considerable interest and speculation for over a decade. Chapter 4 provides insight into the dinitrogen and dihydrogen affinity of an iron(I) complex. Chapter 5 details the experimental procedures performed in this work.
10
Curley, John Joseph. "Dinitrogen fixation chemistry of a molybdenum trisanilide system". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/49549.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Vita.
Includes bibliographical references.
Dinitrogen cleavage by Mo(N[t-Bu]Ar)3 (Ar = 3,5-C6H3Me2) proceeds through the intermediate ([mu]-N2)[Mo(N[t-Bu]Ar)3]2 before forming N=Mo(N[t-Bu]Ar)3 as the product. Both the intermediate bridging N2 complex and the nitride product have been structurally characterized by single-crystal X-ray diffraction. The spectroscopic and structural features of this bridging N2 complex are discussed in comparison to its one- and two-electron oxidized congeners, [([mu]-N2)[Mo(N[t-Bu]Ar)3]2]n+, n = 1, 2. This series of three complexes share a common chromophore, the nature of which was identified with the aid of time-dependent density functional theory. A photochemical reaction of ([mu]-N2)[Mo(N[t-Bu]Ar)3]2 that forms both Mo(N[t-Bu]Ar)3 and N=Mo(N[t-Bu]Ar)3 is described. The dynamics of this photochemical reaction are explored by ultrafast transient absorbance spectroscopy. A synthetic scheme for nitrogen fixation in the form of organic nitriles is initiated from the product of dinitrogen cleavage, N=Mo(N[t-Bu]Ar)3. This synthetic scheme is a closed cycle that returns the molybdenum nitride starting material at the conclusion of the cycle. To achieve this synthetic goal, new methods were developed to form C-N bonds between organic electrophiles and the weakly nucleophilic terminal nitride. In a key reaction, Mo(IV) ketimide complexes, R'O(R)CNMo (N[t-Bu]Ar)3, were shown to react with either SnCl2 or ZnCl2 to afford the corresponding nitrile, RCN, and a ClMo(N[t-Bu]Ar)3 in essentially quantitative yields.
(cont.) The chloromolybdenum complex may be reductively recycled to yield Mo(N[t-Bu]Ar)3 for subsequent dinitrogen cleavage. A series of cationic diazoalkane complexes [4-RC6H4C(H)NNMo(N[t-Bu]Ar)3][AlCl4], R = NMe2, Me, H, Br, CN, have been prepared by treatment of the N2-derived diazenido complex Me3SiNNMo(N[t-Bu]Ar)3 with 4-RC6H4CHO and 2 equiv AlCl3. The physical properties of these complexes were determined by the use of X-ray crystallography, cyclic voltammetry, infrared, Raman, UV-vis, and 15N NMR spectroscopies. Electrochemical reduction of these cationic diazoalkane complexes forms the C-C bonded dimer, [mu]-(4-RC6H4C(H)NN)2[Mo(N[t-Bu]Ar)3]2, in a reaction that is proposed to proceed through the neutral, odd-electron complex 4-RC6H4C(H)NNMo(N[t-Bu]Ar)3. The structure of this odd-electron compound is described with the aid of density functional theory. The central C-C bond in [mu]-(4-RC6H4C(H)NN)2[Mo(N[t-Bu]Ar)3]2 is redox non-innocent, and oxidation of these compounds returns the cationic diazoalkane complex from which they were prepared.
by John Joseph Curley.
Ph.D.
11
Guest, Ruth Winifred. "Synthesis and Reactions of Iron and Ruthenium Dinitrogen Complexes". University of Sydney, 2008. http://hdl.handle.net/2123/3533.
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Doctor of Philosophy (PhD)This thesis is primarily concerned with the synthesis and reactions of iron and ruthenium dinitrogen complexes of tripodal phosphine ligands. Of particular interest is the cationic dinitrogen bridged iron complex [(FeH(PP3))2(μ-N2)]2+ 23, containing the tetradentate ligand P(CH2CH2PMe2)3, PP3 1, and its potential for facilitating the reduction of the bound dinitrogen upon treatment with acid. The synthesis of a selection of novel and known tripodal phosphine and amino phosphine ligands is described. New ligands N(CH2CH2CH2PMe2)3 N3P3 7 and P(CH2CH2CH2PiPr2)3 P3Pi3 11 were synthesised by nucleophilic displacement of bromide from the bromoalkylphosphine and bromoalkylamine precursors with the relevant phosphide. A new method for synthesis of known ligand P(CH2CH2CH2PMe2)3 P3P3 19 by the nucleophilic substitution of its chloroalkylphosphine oxide with dimethylphosphide and subsequent reduction is also reported. The reaction of [(FeH(PP3))2(μ-N2)]2+ 23 with base produced the singly deprotonated mixed valence species [(FeH(PP3))(μ-N2)(Fe(PP3))]+ 37 and subsequently the iron(0) dinuclear species (Fe(PP3))2(μ-N2) 38 and mononuclear complex Fe(N2)(PP3) 44. The 15N labelling of complexes has allowed the 15N NMR spectra of 23, 37 and 44 to be reported along with the observation of a long-range 5JP-P coupling across the bridging dinitrogen of 37. Complexes 23 and 37 were also structurally characterised by X-ray crystallography. The treatment of a variety of iron PP3 1 dinitrogen complexes, including the mononuclear species [(Fe(N2)H(PP3)]+ 22, with acid, or base then acid, did not result in the formation of ammonia from reduction of the complexed dinitrogen. The reactions of FeCl2(PP3) 24 and FeClH(PP3) 25 with ammonia and hydrazine afforded the complexes [FeCl(N2H4)(PP3)] 48, [FeH(N2H4)(PP3)] 47, [FeCl(NH3)(PP3)] 49 and [FeH(NH3)(PP3)] 46. Complexes 47 and 46 are considered potential intermediates in any reduction of the dinitrogen ligand of 23 to ammonia. Complexes 49 and 46 were also formed from the decomposition of the hydrazine complexes 48 and 47. The 15N NMR shifts, derived from both the 15N labelling of complexes and from 1H-15N 2D NMR experiments at natural abundance are reported. In addition, complex 47 was characterised by X-ray crystallography. The novel ligand P(CH2CH2PiPr2)3 PPi3 12 was used in the successful synthesis of [FeCl(PPi3)]+ 51 and [RuCl(PPi3)]+ 56. Reduction of 51 and 56 with potassium graphite under dinitrogen afforded the complexes Fe(N2)(PPi3) 52 and Ru(N2)(PPi3) 57 respectively. This is the first report of a Ru(0) dinitrogen complex. Treatment of 52 and 57 with lutidinium tetrafluoroborate resulted in protonation and oxidation of the metal centre to afford the hydrido complexes [Fe(N2)H(PPi3)]+ 53 and [Ru(N2)H(PPi3)]+ 58 respectively. 15N labelled analogues of 52, 53, 57 and 58 were achieved by exchange reactions with 15N2 gas, allowing for analysis by 15N NMR spectroscopy. Species 52, 57 and 58 have also been structurally characterised by X-ray crystallography. Treatment of 52 with excess acid in THF afforded both 53 and the dihydrogen complex [Fe(H2)H(PPi3)]+ 54. The mechanism of formation of 54 probably involves the C-H activation of the solvent THF. The complex cation [RuCl(P3Pi3)]+ 65 was synthesised using the novel ligand P3Pi3 11. A polymeric iron(II) complex, [Fe2Cl4(N3P3)2]n 66, of the tridentate ligand N3P3 7 was also synthesised. Characterisation of both 65 and 66 by X-ray crystallography is reported. (FeCl)2(μ-Cl)2(μ-Pi2)2 68, an unusual bridged dimer of the known ligand CH2(PiPr2)2 Pi2 67, and iron(II) and iron(0) tetramers of the PP3 1 ligand, namely [Fe4Cl4(PP3)5]4+ 71 and Fe4(PP3)5 72 were also characterised by X-ray crystallography.
12
Larsen, Julie Melissa. "Measuring dinitrogen gas emissions from a lagoon treatment system". NCSU, 2004. http://www.lib.ncsu.edu/theses/available/etd-01052004-223912/.
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A method for collecting dinitrogen gas emissions from open pond waste treatment systems was developed. The method was critically tested in a laboratory for sources of air contamination to ensure reliable gas measurements. A laboratory experiment was done to estimate the rate at which dissolved dinitrogen would be stripped out of solution due to non-dinitrogen bubbles rising through the water column. A volumetric mass transfer coefficient for the process was estimated for clean water. The gas collection method was implemented in a partially aerated lagoon treatment system for dinitrogen and methane gas sampling. The volumetric mass transfer coefficient found in the laboratory for clean water was adjusted to compensate for field gas production rates, temperatures and wastewater quality to estimate the rate of stripped dinitrogen from the partially aerated lagoon. The estimated rate of stripped dinitrogen was subtracted from the total measured dinitrogen flux to estimate the dinitrogen produced biologically. Results from laboratory testing revealed that dinitrogen can be measured with low amounts of dinitrogen atmospheric contamination (0.57% N2) and the preliminary field results suggest that biological denitrification did occur at this lagoon treatment system.
13
Pappas, Iraklis. "Fundamental investigations into dinitrogen fixation by group 4 metals". Thesis, Princeton University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10120357.
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Addition of terminal or internal alkynes to a base free titanocene oxide results in synthesis of the corresponding oxometallocyclobutene. With appropriate cyclopentadienyl substitution, these compounds undergo reversible C-C reductive elimination offering a unique approach to cyclopentadienyl modification. Subsequent reactivity demonstrates the complete scission of the Ti=O multiple bond.
Cycloaddition of monosubstituted allenes with a monomeric, base free titanocene oxide resulted in isolation and crystallographic characterization of the corresponding oxatitanacyclobutanes. In solution these compounds are a mixture of (E) and (Z) isomers and interconvert by mechanisms that are dependent on the specific substitution of the allene. Facile carbonylation of the oxatitanacyclobutanes was also observed to yield rare examples of structurally characterized oxatitanacyclopentanones. These studies highlight the new chemistry available from synthesis of base free titanocene oxide compounds enabled by appropriate cyclopentadienyl substitution.
The hydrogenolysis of titanium nitrogen bonds in a family of bis(cyclopentadienyl) titanium amides, hydrazides, and imides via proton coupled electron transfer (PCET) is demonstrated. (η5-C5Me5)(py-Ph)Rh-H (py-Ph = 2-pyridylphenyl, [Rh]-H) and (η5- C5R5)(CO)3CrH ([Cr]R-H, R= H, Me) were used as catalysts for homolytic H2 activation followed by PCET to the nitrogen-containing fragment. Detailed mechanistic studies and an analysis of the underlying thermochemistry are employed to explain the decreased catalytic efficiency of [Cr]R-H compared to [Rh]-H. The N-H bond dissociation free energies (BDFEs) in 12 structurally similar compounds were determined through a combination of experimental and computational methods, providing a foundation for the use of N-H BDFEs as a metric to enable NH3 synthesis from H 2 and N2 at a well-defined metal center.
Combination of the readily available a-diimine ligand, ((ArN=C(Me)) 2 Ar = 2,6-iPr2-C6H3), (iPrDI) with air-stable nickel(II) bis(carboxylates) generated a highly active catalyst exhibiting anti-Markovnikov selectivity for the hydrosilylation of alkenes with (EtO)3SiH. The exclusive selectivity for formation of terminal alkyl silanes was also observed with internal alkenes via a tandem isomerization-hydrosilylation pathway. The hydrosilylation of 1-octene with triethoxysilane, a reaction performed commercially in the silicones industry on a scale of > 12,000,000 lbs/year, was performed on a 10 g scale with 96 % yield and >98 % selectivity for the desired product.
14
Guest, Ruth Winifred. "Synthesis and reactions of iron and rutheniuim dinitrogen complexes". Connect to full text, 2008. http://ses.library.usyd.edu.au/handle/2123/3533.
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Thesis (Ph. D.)--University of Sydney, 2008.Includes tables. Includes list of publications: leaves i-ii. Title from title screen (viewed October 30, 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Chemistry, Faculty of Science. Includes bibliographical references. Also available in print form.
15
Lancaster, Norman Llewellyn. "Solid-supported aromatic nitrations". Thesis, University of Exeter, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302641.
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The efficacy of the claycop system in the nitration and the dinitration of toluene has been investigated.Comparison of regioselectivity and of rate constant with homogeneous nitric acid nitration was made. The use of ion-exchanged montmorillonite clay as a catalyst for acetyl nitrate nitration was studied. The system was found to enhance Para selectivity in the nitration of toluene and to catalyse the reaction. Additionally, the catalyst was shown to be recyclable. The reaction of toluene was too fast to allow kinetic study. However, kinetic study was possible,using chlorobenzene as substrate.Again, the system was found to decrease both the reaction time and the o-/ p- ratio. It was possible to demonstrate a dependence of rate constant upon mass of clay. The effect of the counter ion was investigated and the use of trifluoroacetyl anhydride was studied. A new system for aromatic nitration has been developed in this work using zeolite with dinitrogenp entoxide.A series of zeolites were screened in the nitration of onitrotoluene, with the H-faujasites showing the quickest reaction times and highest degree of regioselectivity. The silica/ alumina ratio of the faujasite used was varied and this was shown to have an effect on regioselectivity. However, reactions were too fast for kinetic study. The faujasite/ dinitrogen pentoxide system was used in the nitration of some deactivated benzenes using these substrates allowed kinetic studies to be made and the order in each component to be determined. It was found that nitration was zeroth order in dinitrogen pentoxide, that the reaction obeyed a first order rate law, and that the first order rate constant was proportional to the mass of zeolite used. Comparison of the relative rates of nitration of 1-chloro-2-nitrobenzene1, -chloro-4-nitrobenzene and nitrobenzeneb y this system to the relative rate constants of nitronium ion nitration was made. The similarity suggested that the mechanism of nitration by faujasite/d initrogen pentoxide might involve nitronium ion transfer.Amongst the H-faujasites of different silica/ alumina ratio, the rate constant was shown to increase with the aluminium content. A mechanism is proposed in which zeolite protons (present in proportion to the aluminium atoms) are first replaced by nitronium ions. The latter are transferred to the aromatic in the rate-determining step. The use of non-chlorinated solvents and the recycling of zeolite were both studied, and the nitration of 2,6-dinitrotoluene was attempted. The use of the faujasite/ dinitrogen pentoxide system was extended to the nitration of nitrogen containing aromatic heterocycles direct C-nitration of quinolone was not possible, only N-nitration. However, pyrazole was converted to 1,4-dinitropyrazole quickly and cleanly under mild conditions. It was shown that the N-nitration occurred instantly, followed by slower C-nitration. The kinetics of the second nitration were studied and comparison with deactivated benzenes was made.
16
Zhu, Ting. "Zirconium complexes of cyclopentene-bridged diamidophosphine ligands for dinitrogen activation". Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/28114.
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The synthesis of two new diiminophosphine proligands, CY⁵[NPN]DMPH₂ (DMP = 2,6-Me₂C₆H₃) and CY⁵[NPN]DIPPH₂ (DIPP = 2,6-iPr2C₆H₃), is reported. These two proligands feature a cyclopentane ring linker between the phosphine and imino donors. The precursors of the proligands were prepared from cyclopentanone and the corresponding substituted aniline. After lithiation and slow addition of PhPCl₂, the diiminophosphine proligands could be obtained. It is easy to vary the bulkiness of the proligands in this synthetic strategy. The synthesis of a diamidodioxo ligand based on the scaffold of calix[4]arene was also attempted.
The bis(dimethylamido)zirconium complexes of the two ligands, CY⁵[NPN]DMP and CY⁵[NPN]DIPP, were prepared via protonolysis from the proligands and Zr(NMe₂)₄. The dichlorozirconium or diiodozirconium species could be obtained from the corresponding bis(dimethylamido)zirconium complex upon addition of excess Me₃SiCl or Me₃SiI. Most of the zirconium complexes are well characterized in the solid state by single crystal X-ray diffraction.
A Zr-N₂ complex, {CY⁵[NPN]DMPZr(THF)}₂(µ-η²:η²-N₂), was synthesized from CY⁵[NPN]DMPZrCl₂ and 2.2 equivalents of KC₈ in THF under 4 atm of N₂. By single crystal X-ray analysis, N₂ has been reduced to an N₂4- unit and is side-on bound to two Zr atoms. However, large number of side products was observed in the reaction. The reduction of CY⁵[NPN]DIPPZrCl₂ was also attempted. From the minor product identified from single crystal X-ray diffraction, the cyclopentene ring linker was cleaved in the reduction of CY⁵[NPN]DIPPZrCl₂.
17
Mohr, Wiebke [Verfasser]. "Dinitrogen fixation in the unicellular diazotroph Crocosphaera watsonii / Wiebke Mohr". Kiel : Universitätsbibliothek Kiel, 2010. http://d-nb.info/1025370759/34.
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Crawford, Andrew Dixie. "Proton and electron transfers to dinitrogen on iron phosphine complexes". Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/64816.
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The conversion of atmospheric dinitrogen to ammonia is the starting point for the formation of all nitrogen-containing compounds on earth, and is consequently a hugely important chemical transformation. The anthropogenic production of ammonia currently requires enormous amounts of energy, and reducing this energy cost is acknowledged to be a major challenge to research chemistry. Efforts over the last 60 years to realise this goal have taken inspiration from the existing anthropogenic and biological systems capable of performing the fixation of dinitrogen to ammonia, both of which require transition metal catalysts. Synthetic transition metal complexes are capable of catalysing homogeneous dinitrogen fixation increasingly effectively, and iron complexes have moved to the forefront of research in this area. This dissertation explores a broad range of factors relevant to dinitrogen fixation at simple iron phosphine complexes, which have recently been shown to mediate this important transformation extremely efficiently. Chapter 1 introduces the broader context in which these investigations were performed, and outlines current areas of investigation in the field. Chapter 2 then details the preparation of a novel iron bisphosphine framework, and its application to homogeneous dinitrogen fixation. In Chapter 3, alternative iron phosphine complexes with tripodal ligand architectures are discussed, and the results of investigations into the functionalisation of coordinated dinitrogen with protons and other electrophiles are reported. Chapter 4 then describes the possible use of dihydrogen as a source of protons and electrons in homogeneous dinitrogen fixation, and the preparation of unusual tripodal hydride and dihydrogen complexes in this context. Chapter 5 provides the experimental details for all of the investigations performed. Additional materials, including crystallographic data, are given in the Appendix.
19
Hill, Peter. "The activation and fixation of dinitrogen by iron phosphine complexes". Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/45533.
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Dinitrogen gas is the source of all biologically and industrially fixed nitrogen, yet the activation of this highly unreactive molecule is a significant challenge in modern chemistry. The current industrial route to fixed nitrogen compounds is the Haber-Bosch process, a reaction which has remained largely unaltered since the early 20th century. The catalytic fixation of N2 by molecular Fe complexes, by contrast, is a young and rapidly developing field, yet thus far few complexes can effect this transformation. This thesis explores the reactivity of electron-rich Fe phosphine complexes as potential catalysts for this transformation.
20
Wood, Simon Andrew. "Corrosion studies in liquid nitrogen oxides". Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262774.
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Chin, Jia Min. "Synthesis and studies of molybdenum and tungsten complexes for dinitrogen reduction". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/57567.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2010.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Vita. Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references.
A series of monopyrroletriamine ligands [Arpyr(Ar')2]H3 of the form ArC4H2NHCH2N(CH2CH2NHAr')2 (Ar = 2,4,6-mesityl (Mes), 2,4,6-triisopropylphenyl (TRIP); Ar' = C6F5, 2-tolyl (o-tol), naphthyl, 3,5-(2,4,6-triisopropylphenyl)phenyl (HIPT), 3,5- dimethylphenyl, 3,5-di-tert-butylphenyl were synthesized. [Mespyr(C6F5)2]MoCl, ([Mespyr(C6F5)2]Mo = MesitylC4H2NCH2N(CH2CH2NC6F5)2) was prepared by reaction of [Mespyr(C6F5)2]H3 with MoCl4(THF)2 and base and [Mespyr(3,5-t-Bu)2]MoCl and [Mespyr(3,5- Me)2]MoCl (3,5-t-Bu=3,5-di-tert-butylphenyl, Me = 3,5-dimethylphenyl) were synthesized likewise. All three monochlorides are paramagnetic. [Mespyr(C6F5)2]MoNMe2, [[Mespyr(otol) 2]MoNMe2, [Mespyr(3,5-t-Bu)2]MoNMe2, [Mespyr(3,5-Me)2]MoNMe2 were synthesized by reaction of the ligands with Mo(NMe2)4. The resulting compounds are diamagnetic and range in color from teal blue to emerald green. These low spin monodimethylamide complexes exist in rapid equilibria with their high spin forms. [Mespyr(C6F5)2]MoN and [Mespyr(3,5-t-Bu)2]MoN were synthesized by reaction of their respective monochlorides with NaN3 and are yellow diamagnetic species. Reaction of [Mespyr(3,5-t-Bu)2]MoN with Et3OBF4 leads to {[Mespyr(3,5- t-Bu)2]MoNEt}BF4, also a diamagnetic yellow species. [Mespyr(C6F5)2]MoOTf is synthesized by the reaction of [Mespyr(C6F5)2]MoCl with AgOTf. Reduction of [Mespyr(3,5-t-Bu)2]MoCl with Na under N2 led to [Mespyr(3,5-t-Bu)2]MoNNNa(THF)x, several species with varying numbers of THF coordination, x. A single species can be obtained when [Mespyr(3,5-t- Bu)2]MoNNNa(THF)x is reacted with either NBu4Cl or 15-crown-5 ether to yield purple green 4 {[Mespyr(3,5-t-Bu)2]MoNN}NBu4 or [Mespyr(3,5-t-Bu)2]MoNNNa(15-c-5). All the diazenide species are diamagnetic. Oxidation of the diazenide with AgOTf yields [Mespyr(3,5-t- Bu)2]Mo(N2). [Mespyr(3,5-t-Bu)2]Mo(CO) is synthesized by exposure of [Mespyr(3,5-t- Bu)2]Mo(N2) to CO. Reaction of [Mespyr(3,5-t-Bu)2]MoCl with NaBPh4 and NH3 yields {[Mespyr(3,5-t-Bu)2]Mo(NH3)}BPh4. Catalytic runs employing [Mespyr(3,5-t-Bu)2]MoN as the catalyst yielded one equivalent of NH3. A triamidoamine ligand [(HIPTNCH2CH2CH2)3N]3- was synthesized and metalated with MoCl4(THF)2 to produce [(HIPTNCH2CH2CH2)3N]MoCl ([HIPTtrpn]MoCl). Reduction of [HIPTtrpn]MoCl by KC8 under an atmosphere of dinitrogen leads to the green species [HIPTtrpn]MoNNK which can be oxidized by ZnCl2(dioxane) to produce [HIPTtrpn]Mo(N2). Other complexes synthesized include {[HIPTtrpn]Mo(NH3)}+ salts and [HIPTtrpn]Mo(CO). Xray studies were carried out on [HIPTtrpn]MoN and {[HIPTtrpn]Mo(NH3)}BAr'4. This system is not catalytic for the reduction of dinitrogen to ammonia and studies were carried out to elucidate the reasons. Oxidation studies were carried out on [HIPTN3N]Mo(N2) and [HIPTN3N]W(N2) ([HIPTN3N] = [(HIPTNCH2CH2)3N]3-). The rate of conversion of [HIPTN3N]Mo(NH3) to [HIPTN3N]Mo(N2) was studied and found to be increased in the presence of BPh3. [HIPTN3N]Mo(N2) conversion to [HIPTN3N]Mo(CO) was found to be dependent on CO pressure. Protonation studies of [HIPTN3N]Mo(N2) were also carried out. Studies of [HIPTN3N]MoNNH decomposition showed that decomposition is not base-catalyzed. [HIPTN3N]W(CO) was synthesized by exposure of [HIPTN3N]W(N2) to CO. It is a green, paramagnetic compound and its use as a standard (for determining relative concentrations of other compounds in the IR sample) in IR spectroscopic studies appears to be promising. [HIPTN3N]MoCNH2 was synthesized by addition of acid and reducing agent to [HIPTN3N]MoCN and is a yellow, diamagnetic compound. Two triamidophosphine ligands, triHIPTamine and tri-n-Buamine were synthesized. Metalation of Zr(NMe2)4 with these ligands leads to formation of pn3HIPTZrNMe2 and pn3-n- BuZrNMe2, both diamagnetic, pale yellow complexes.
by Jia Min Chin.
Ph.D.
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Butler, Mark Damian. "Dinitrogen oxide emissions as an early warning indicator for nitrification failure". Thesis, Cranfield University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539396.
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O'Donoghue, Myra Brigid 1966. "Dinitrogen and organometallic chemistry of trimethylsilyl-substituted triamidoamine complexes of molybdenum". Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/50544.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1999.Includes bibliographical references.
{ [N 3N]Mo-N=N} 2Mg(THF)2, isolated from the reduction of [N3N]MoCl by magnesium powder under dinitrogen, serves as an entry into the dinitrogen chemistry of molybdenum complexes containing the TMS-TREN ligand. ... Five coordinate tungsten oxo alkylidene complexes of the general type (ArO)2W(O)(CHtBu)(PR 3 ) (Ar = 2,6-Ph2C6H3 ) are synthesized by reaction of Ta(CHtBu)(PR 3)2X3 (X = Cl, Br) with W(O)(OtBu) 4. 1H NMR spectroscopy reveals that only the syn rotamer is present in solution and PPh2Me is labile on the NMR time scale.
by Myra Brigid O'Donoghue.
Ph.D.
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Tronoff, Ashley. "Chloride abstraction from ruthenium alkyl bis-diphosphine dichlorides". Thesis, The University of Sydney, 2008. http://hdl.handle.net/2123/2801.
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Despite their early discovery, relatively few classes of ruthenium dinitrogen complexes are known. This work describes the successful coordination of dinitrogen to the electron-rich alkylphosphine cores [RuCl(dmpe)2]+ and [RuCl(depe)2]+ by chloride abstraction from both the cis and trans dichloro derivatives. One such complex, trans-[RuCl(N2)(dmpe)2](BArF24), possesses the most activated ruthenium νNN reported to date. A variety of chloride abstraction agents were tested on the cis and trans isomers of [RuCl2(P-P)2] (P-P = dmpe, depe) with the choice of abstracting agent, anion and solvent all found to significantly affect the outcome. Reaction with silver triflate and trimethylsilyl triflate was found to give dichlororuthenium(III) products, which could be readily reduced to the ruthenium(II) starting materials with common reducing agents, as well as by alcohols and hydrazine. The use of thallium triflate avoided oxidation and led to the formation of the crystallographically characterised polymeric incorporation product, [{trans-[RuCl2(dmpe)2]•Tl(OTf)}n] from trans-[RuCl2(dmpe)2] and the interesting chloride-bridged ruthenium dimer cis-[{Ru(depe)2}2(μ-Cl)2](OTf)2 from trans-[RuCl2(depe)2]. Anion exchange of the complex [{trans-[RuCl2(dmpe)2]•Tl(OTf)}n] with the non-coordinating anion tetrakis(3,5-bis(trifluoromethyl)phenyl)borate resulted in removal of thallium from the system and coordination of dinitrogen to give trans-[RuCl(N2)(dmpe)2](BArF24). Cis-[{Ru(depe)2}2(μ-Cl)2](OTf)2 was found to readily react with a variety of small ligands and gave products such as cis-[RuCl(CO)(depe)2](OTf), cis-[RuCl(NCMe)(depe)2](OTf), cis-[RuCl(CNtBu)(depe)2](OTf), cis-[RuCl(NH3)(depe)2](OTf), cis-[RuCl(N3)(depe)2], and trans-[RuCl(η2-H2)(depe)2](OTf). A preliminary X-ray single crystal structure analysis was conducted on the complex cis-[RuCl(CNtBu)(depe)2](OTf). The thallium(I) salt Tl(BArF24) was found to be an efficient chloride abstraction agent under mild conditions. Reactions with cis- and trans-[RuCl2(depe)2] and cis-[RuCl2(dmpe)2] furnished dinitrogen complexes of the form cis-[{RuCl(P-P)2}2(μ-N2)](BArF24)2, whilst reaction of trans-[RuCl2(dmpe)2] with Tl(BArF24) led to the stable five-coordinate complex trans-[RuCl(dmpe)2](BArF24). Vapour diffusion techniques applied to a solution of cis-[{RuCl(depe)2}2(μ-N2)](BArF24)2 gave rise to crystals of trans-[RuCl(N2)(depe)2](BArF24), on which preliminary X-ray molecular structure analysis was performed. Reactions of both cis-[{Ru(depe)2}2(μ-Cl)2](OTf)2 and trans-[RuCl2(dmpe)2] with high pressure (140 psi) dinitrogen at 140 150°C in methanol or tetrahydrofuran resulted in solvent carbonyl abstraction to afford trans-[RuCl(CO)(depe)2](OTf) and trans-[RuCl(CO)(dmpe)2](Cl) from the depe and dmpe complexes respectively. The molecular structure of trans-[RuCl(CO)(dmpe)2](Cl) was determined via single crystal X-ray structure analysis.
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Tronoff, Ashley. "Chloride abstraction from ruthenium alkyl bis-diphosphine dichlorides". Science, 2008. http://hdl.handle.net/2123/2801.
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Doctor of Philisophy (PhD)Despite their early discovery, relatively few classes of ruthenium dinitrogen complexes are known. This work describes the successful coordination of dinitrogen to the electron-rich alkylphosphine cores [RuCl(dmpe)2]+ and [RuCl(depe)2]+ by chloride abstraction from both the cis and trans dichloro derivatives. One such complex, trans-[RuCl(N2)(dmpe)2](BArF24), possesses the most activated ruthenium νNN reported to date. A variety of chloride abstraction agents were tested on the cis and trans isomers of [RuCl2(P-P)2] (P-P = dmpe, depe) with the choice of abstracting agent, anion and solvent all found to significantly affect the outcome. Reaction with silver triflate and trimethylsilyl triflate was found to give dichlororuthenium(III) products, which could be readily reduced to the ruthenium(II) starting materials with common reducing agents, as well as by alcohols and hydrazine. The use of thallium triflate avoided oxidation and led to the formation of the crystallographically characterised polymeric incorporation product, [{trans-[RuCl2(dmpe)2]•Tl(OTf)}n] from trans-[RuCl2(dmpe)2] and the interesting chloride-bridged ruthenium dimer cis-[{Ru(depe)2}2(μ-Cl)2](OTf)2 from trans-[RuCl2(depe)2]. Anion exchange of the complex [{trans-[RuCl2(dmpe)2]•Tl(OTf)}n] with the non-coordinating anion tetrakis(3,5-bis(trifluoromethyl)phenyl)borate resulted in removal of thallium from the system and coordination of dinitrogen to give trans-[RuCl(N2)(dmpe)2](BArF24). Cis-[{Ru(depe)2}2(μ-Cl)2](OTf)2 was found to readily react with a variety of small ligands and gave products such as cis-[RuCl(CO)(depe)2](OTf), cis-[RuCl(NCMe)(depe)2](OTf), cis-[RuCl(CNtBu)(depe)2](OTf), cis-[RuCl(NH3)(depe)2](OTf), cis-[RuCl(N3)(depe)2], and trans-[RuCl(η2-H2)(depe)2](OTf). A preliminary X-ray single crystal structure analysis was conducted on the complex cis-[RuCl(CNtBu)(depe)2](OTf). The thallium(I) salt Tl(BArF24) was found to be an efficient chloride abstraction agent under mild conditions. Reactions with cis- and trans-[RuCl2(depe)2] and cis-[RuCl2(dmpe)2] furnished dinitrogen complexes of the form cis-[{RuCl(P-P)2}2(μ-N2)](BArF24)2, whilst reaction of trans-[RuCl2(dmpe)2] with Tl(BArF24) led to the stable five-coordinate complex trans-[RuCl(dmpe)2](BArF24). Vapour diffusion techniques applied to a solution of cis-[{RuCl(depe)2}2(μ-N2)](BArF24)2 gave rise to crystals of trans-[RuCl(N2)(depe)2](BArF24), on which preliminary X-ray molecular structure analysis was performed. Reactions of both cis-[{Ru(depe)2}2(μ-Cl)2](OTf)2 and trans-[RuCl2(dmpe)2] with high pressure (140 psi) dinitrogen at 140 150°C in methanol or tetrahydrofuran resulted in solvent carbonyl abstraction to afford trans-[RuCl(CO)(depe)2](OTf) and trans-[RuCl(CO)(dmpe)2](Cl) from the depe and dmpe complexes respectively. The molecular structure of trans-[RuCl(CO)(dmpe)2](Cl) was determined via single crystal X-ray structure analysis.
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Jayasundara, H. P. S. "Productivity, dinitrogen fixation and nitrogen transfer in some legume based cropping systems". Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386547.
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Lamarche, Vanessa Mercia Elizabeth. "The activation of dinitrogen by vanadium diamido-amine complexes and related studies". Thesis, University of Sussex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249113.
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Stephens, Alan Nicholas. "Niobium dithiocarbamates : structural and solution studies in relation to a bridged-dinitrogen complex". Thesis, University of Sussex, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236255.
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Little, Richard Howard. "Regulatory and enzymatic mechanisms controlling the fate of dioxygen and dinitrogen in proteobacteria". Thesis, University of East Anglia, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405915.
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Helleren, Caroline Anne. "A search for bridging-dinitrogen heterobimetallic complexes containing iron and molybdenum or tungsten". Thesis, University of Sussex, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241719.
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Jones, Benjamin. "Airborne measurements of organic acids, inorganic acids and other trace gas species in the remote regions of the Northern Hemisphere using a Chemical Ionisation Mass Spectrometer (CIMS)". Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/airborne-measurements-of-organic-acids-inorganic-acids-and-other-trace-gas-species-in-the-remote-regions-of-the-northern-hemisphere-using-a-chemical-ionisation-mass-spectrometer-cims(b67b7cf5-3ca1-4aaf-ab41-66c2b41c4a2f).html.
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Formic acid and nitric acid have been found to contribute to aerosol formation and are key components of acidity in the troposphere. Tropospheric measurements of these species are often limited, resulting in major uncertainties when assessing their effects on the climate. Current global chemistry-transport models significantly under-predict formic acid concentrations, particularly in the mid-to-high latitudes of the Northern Hemisphere. Furthermore, large discrepancies exist in the role played by dinitrogen pentoxide on nitric acid production between two recently documented models assessing the global nitric acid budget. In order to accurately constrain the budget of these acids in the mid-to-high latitudes of the Northern Hemisphere, it is crucial that these uncertainties are addressed. In this work, airborne measurements of formic acid, nitric acid and dinitrogen pentoxide are presented from across different regions of the Northern Hemisphere to investigate direct and indirect sources contributing to the formic acid and nitric acid regional budgets. Measurements were collected using a Chemical Ionisation Mass Spectrometer (CIMS) fitted to the Facility for Atmospheric Airborne Measurements (FAAM) BAe-146 aircraft. Formic acid measurements within the European Arctic during March and July 2012 would indicate ocean sources dominate over terrestrial sources irrespective of seasonality. CH2I2 photolysis and oxidation was hypothesised as a marine source of formic acid. Modelled estimates would indicate the CH2I2 reaction route may represent a significant summer marine source of formic acid within the Fenno-Scandinavian Arctic. Additionally, low altitude aircraft measurements taken within the Fenno-Scandinavian Arctic over regions occupied by wetlands in August 2013 were used to calculate a formic acid surface flux. Results would suggest formic acid emission from wetlands may represent up to 37 times greater than its globally inferred estimate. A flux measurement conducted over a comparable region in September 2013 observed a negative flux, indicating a change of this region from a net source to a net sink of formic acid. The inconsistency of this regional wetland source confirms the need for in-depth studies on formic acid emission from wetlands, in order to better understand its contribution to the regional and global formic acid budget. In a separate study, significant daytime elevations of N2O5 and HNO3 concentrations were observed within identified biomass burning plumes off the eastern coast of Canada. In-plume correlations between N2O5 and HNO3 concentrations observed within these environments suggest N2O5 was acting as additional daytime source of gaseous HNO3 when subjected to photolytically-limited conditions. This result has important implications to ozone production and provides evidence for an additional daytime source of nitric acid, which must be included in chemistry models calculating the global nitric acid budget.
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Crossland, Justin L. 1982. "Iron coordination chemistry of nitrogen, diazene, hydrazin, and ammonia : Investigating the mechanism of nitrogen reduction to ammonia". Thesis, University of Oregon, 2009. http://hdl.handle.net/1794/10336.
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xvi, 233 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.The coordination chemistry of iron with N 2 is becoming increasingly important as chemists try to find alternative routes to the production of ammonia. Current biological and industrial processes use iron to catalyze the formation of ammonia from N 2 ; however, huge amounts of energy are required for this conversion. Understanding how dinitrogen and other intermediates of dinitrogen reduction interact with iron could lead to energy efficient processes for the production of ammonia. This dissertation explores the synthesis and reactivity of an iron dinitrogen complex that reacts with acid to produce ammonia at room temperature and pressure. This dissertation also explores the progress toward determining the mechanism of this reaction in hopes of improving the yields of ammonia. Chapter I describes both the biological nitrogen fixation process and the industrial production of ammonia and provides an in-depth look at progress toward an alternative route to ammonia using iron complexes described in the literature thus far. Chapter II details the synthesis, characterization, and reactivity of dihydrogen and dinitrogen complexes of iron. These complexes are precursors to the active ammonia producing complex and are among a handful of dihydrogen and dinitrogen complexes that have been structurally characterized. Chapter III explores the synthesis and stability of Fe(DMeOPrPE) 2 N 2 . This complex produces ammonia and hydrazine upon protonation with a strong acid. Optimizing the yield of ammonia from this protonation is also described. Chapter IV discusses the synthesis and reactivity of several complexes of iron containing intermediates relevant to dinitrogen reduction, including diazene (N 2 H 2 ), hydrazine (N 2 H 4 ), and ammonia. By studying these intermediates, a mechanism of ammonia formation from the protonation of Fe(DMeOPrPE) 2 N 2 is proposed that may also provide insights into the mechanism of nitrogenase. Chapter V provides a summary of this research. This dissertation includes previously published and unpublished co-authored material.
Committee in charge: Darren Johnson, Chairperson, Chemistry; David Tyler, Advisor, Chemistry; Michael Haley, Member, Chemistry; Kenneth Doxsee, Member, Chemistry; Scott Bridgham, Outside Member, Biology
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Blacquiere, Johanna M. "New Directions in Catalyst Design and Interrogation: Applications in Dinitrogen Activation and Olefin Metathesis". Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19968.
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A major driving force for development of new catalyst systems is the need for more efficient synthesis of chemical compounds essential to modern life. Catalysts having superior performance offer significant environmental and economic advantages, but their discovery is not trivial. Well-defined, homogeneous catalysts can offer unparalleled understanding of ligand effects, which proves invaluable in directing redesign strategies. This thesis work focuses on the design of ruthenium complexes for applications in dinitrogen activation and olefin metathesis. The complexes developed create new directions in small-molecule activation and asymmetric catalysis by late-metal complexes.
Also examined are the dual challenges, ubiquitous in catalysis, of adequate interrogation of catalyst structure and performance. Insight into both is essential to enable correlation of ligand properties with catalyst activity and/or selectivity. Improved methods for accelerated assessment of catalyst performance are described, which expand high-throughput catalyst screening to encompass parallel acquisition of kinetic data. A final aspect focuses on direct examination of metal complexes, both as isolated species, and under catalytic conditions. Applications of charge-transfer MALDI mass spectrometry to structural elucidation in organometallic chemistry is described, and the technique is employed to gain insight into catalyst decomposition pathways under operating conditions.
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Hess, Fiona Millicent. "o-Phenylene bridged diamidophosphine complexes of groups 4 and 5 metals for dinitrogen activation". Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/51247.
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A series of diamidophosphine donor sets (ipropNPN, tolNPN and phNPN) was prepared, whereby the arylamido groups have no ortho substituents. This allowed for the Buchwald-Hartwig arylamination to be replaced by a directed ortho metalation (DOM) process, sourcing commercial diarylamines. Amido and chloro complexes of Zr, Ti, Hf and Ta with these new diamidophosphine donor sets were prepared.
Reduction of the zirconium dichlorides with KC₈ under N₂ gave the side-on dinitrogen complexes [ipropNPNZr(THF)]₂(µ-η²:η²-N₂) and [tolNPNZr(THF)]₂(µ-η²:η²-N₂) and of titanium dichloride gave the end-on complex [tolNPNTi(THF)]₂(µ-η1:η1-N₂). Compared to previously reported sterically encumbered [mesNPNZr(THF)]₂(µ-η²:η²-N₂), the zirconium complexes were more stable, with longer N-N bonds, less labile THF ligands and shorter Zr-O bond lengths. THF adduct displacement thus occurred less readily; for phosphine donors, displacement was at both zirconium centres i.e. [ipropNPNZr(PPhMe₂)]₂(µ-η²:η²-N₂), compared to the mesNPN analogue with an open site at one of the zirconium centres i.e. [mesNPNZr(PPhMe₂)](µ-η²:η²-N₂)[mesNPNZr]. For titanium, four different pyridine adduct species where observed in solution, but only one species was isolated wherein each THF was displaced by two pyridine molecules i.e. [tolNPNTi(Py)₂]₂(µ-η1:η1-N₂). These new dinitrogen complexes were found to be unreactive with H₂; for zirconium, the lack of an open site at one of the metal centres may explain lack of reactivity, and for titanium, the end-on dinitrogen bonding mode is not amenable to hydrogenolysis.
The potassium salt of tolNPN with TaMe₃Cl₂ gave the trimethyl species tolNPNTaMe₃, but [tolNPNTaMe₄][Li(THF)₄] was isolated from tolNPNTaCl₃ with MeLi. Tantalum hydrides from trimethyl species and H₂ were unstable and did not form dinitrogen complexes, but mass spectra of tantalum trichlorides with KHBEt₃ and N₂ indicated dinitrogen hydrides [NPNTaH]₂(N₂) and further reaction with BEt₃. Reduction of tantalum trichlorides with KC₈ under N₂ gave mass spectra of dinitrogen complexes [NPNTaCl]₂(N₂), with no crystals isolated.Science, Faculty of
Chemistry, Department of
Graduate
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McGarry, Celine. "Synthesis and characterisation of low oxidation state vanadium complexes in relation to dinitrogen fixation". Thesis, University of Surrey, 1994. http://epubs.surrey.ac.uk/843552/.
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The aim of this thesis is to expand knowledge of the coordination chemistry of vanadium(II) because of its importance in chemical and biological systems which reduce dinitrogen to ammonia. A vanadium(II) complex, used extensively in the investigation of the coordination chemistry of vanadium(II), is [VCl2(TMEDA)2], in which TMEDA is N,N,N,N-tetramethylethylenediamine. The corresponding dibromo- and diiodo-complexes were not previously known. Both [VCl2(TMEDA)2] and [VBr2(TMEDA)2] have been successfully prepared by a new method and the mononuclear structure of [VBr2(TMEDA)2] has been confirmed by X-ray crystallography. During attempts to synthesise the corresponding diiodo-complex, [Vl2(TMEDA)2], a whole new area of vanadium(II) chemistry emerged. Metathesis of [VCl2(TMEDA)2] with trimethylsilyl iodide afforded, instead of the expected mononuclear complex [Vl2(TMEDA)2], a novel trinuclear and antiferromagnetic vanadium(II) complex [V3(-C1)5(TMEDA)3]I. By a remarkable coincidence, the carbon, hydrogen and nitrogen analyses expected for both [Vl2(TMEDA)2] and [V3(-CI)5(TMEDA)3]l are identical. An X-ray crystal structure determination showed that [V3(-Cl)5(TMEDA)3]l contains bridging chlorides in the triangulo-[V3Cl3] unit and axial triply-bridged chlorides. An alternative method was then employed in an attempt to isolate [Vl2(TMEDA)2] because the trimethylsilyl iodide had clearly not removed all the chloride from [VCl2(TMEDA)2]. The vanadium(II) iodide [V(MeOH)6]l2, derived from [VCl2(EtOH)2], was treated with TMEDA but another trinuclear complex [V3(?-Cl)3(?-OMe)2(TMEDA)3]l was unexpectedly isolated. This complex contains the triangulo-[V3Cl3] unit and triply-bridged methoxy groups above and below the plane of the triangulo-unit. It seems that a triangulo-unit must also be present in [VCl2(EtOH)2] or formed from it and then carried through the experimental procedure in which [V(MeOH)6]l2 is an intermediate. Therefore, the nature of other complexes prepared from [V(MeOH)6]l2 has been reconsidered and a few preliminary observations with related systems discussed. There is no doubt that the triangulo-[V3Cl3] moiety with either chloride or methoxy ions in the axial positions forms spontaneously because it has considerable stability in vanadium(II) chemistry and that other examples will be found. The elemental analyses of a diiodo complex, prepared by an earlier worker from [V(MeOH)6]l2 and 1,2-bis(diphenylphosphino)ethane (depe), fitted the formulation [V2(depe)5l2]l2 rather than [Vl2(depe)2]. As it had been synthesised from [V(MeOH)6]l2, it was thought that it might be trinuclear. However, recrystallisation gave mononuclear [Vl2(depe)2] confirmed by analysis, mass spectrometry and an X-ray structure determination. This is the first structurally characterised trans diiodide vanadium(II) complex. Complexes of vanadium(II) with N,N-dimethylethylenediamine were successfully prepared and characterised by elemental analyses, infrared spectra and magnetic susceptibility measurements. Schiff bases have been employed to synthesise novel coordinatively unsaturated complexes of vanadium(II) which would contain vacant sites for the coordination of dinitrogen. Many attempts were made to prepare vanadium(II) complexes of tetradentate Schiff bases but in no cases were vanadium(II) products characterised. A reaction involving the bidentate Schiff base Hhappram gave, instead of the hoped for [V(happram)2], the vanadium(III) complex [V(happram)3], the structure of which was determined. Since the coordinatively unsaturated nature of any vanadium(II)-Schiff base complex could facilitate oxidation by impurities, attempts were made to prepare vanadium(II) complexes from heavily substituted bidentate Schiff bases and [VCl2(py)4] in the expectation that the remaining coordination sites would be occupied by pyridine which could be removed at a later stage. A series of novel vanadium(II)-Schiff base complexes was isolated and the corresponding complexes of vanadium (III) were prepared for comparison. Complexes of vanadium(II) with the tetradentate ligands N,N-bis(8-quinolyl)ethylenediamine and N,N-bis(8-quinolyl)1,3-propanediamine were successfully prepared and characterised by elemental analyses, infrared spectra and magnetic susceptibility measurements.
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Oti-Boateng, Charles. "The inhibition by combined nitrogen of dinitrogen fixation in Vicia faba L. ev. Fiord". Adelaide, 1993. http://hdl.handle.net/2440/19107.
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Johnson, Samuel Alan. "Ligand design and the synthesis of reactive organometallic complexes of tantalum for dinitrogen activation". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ61123.pdf.
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Veal, D. A. "Associative cellulolysis and dinitrogen fixation by co-cultures of Trichoderma harzianum and Clostridium butyricum". Thesis, University of Reading, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355941.
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Willmer, Richard Franklin. "Mechanistic studies of nitrations and oxidations in solutions of dinitrogen pentaoxide in nitric acid". Thesis, University of Exeter, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305757.
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Sceats, Emma Louise 1978. "Electronic structure analyses and activation studies of a dinitrogen-derived terminal nitride of molybdenum". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/16665.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2004.Vita.
Includes bibliographical references.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Chapter 1: Complexes obtained by electrophilic attack on a dinitrogen-derived terminal molybdenum nitride: Electronic structure analysis by solid state CP/MAS ¹⁵N NMR in combination ... Chapter 2. Carbene chemistry in the activation of a dinitrogen-derived terminal nitride of molybdenum ... Chapter 3. Nitrogen atom transfer from dinitrogen into an organic nitrile via the anionic ketimide complex (THF)²Mg[O(Ph)C¹⁵NMo(N[tBu]Ar)₃]₂ ...
by Emma Louise Sceats.
S.M.
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Oti-Boateng, Charles. "The inhibition by combined nitrogen of dinitrogen fixation in Vicia faba L. cv. Fiord". Thesis, Adelaide, 1993. http://hdl.handle.net/2440/19107.
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Balesdent, Chantal. "Elucidating the Mechanism of Dinitrogen Reduction to Ammonia: Novel Intermediates in the Protonation of Fe(DMeOPrPE)2N2". Thesis, University of Oregon, 2013. http://hdl.handle.net/1794/13300.
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The reduction of dinitrogen (N2) to ammonia (NH3) will continue to play a vital role in society as the population of the world grows and maintains its dependence on artificial fertilizers. This energy-intensive transformation is achieved industrially by the Haber-Bosch process and naturally via nitrogenase enzymes. Recent synthetic systems attempt to produce NH3 artificially but with lower energy costs than Haber-Bosch by modeling their designs after nitrogenase. This dissertation describes the progress made in one iron-phosphine system, the water-soluble Fe(DMeOPrPE)2N2, capable of producing NH3 at room temperature and pressure.
Chapter I describes the history of the coordination chemistry of N2 to a variety of metals, with a focus on iron complexes. In addition to exploring the range of coordination geometries and supporting ligands of such complexes, the application of N2 coordination complexes towards NH3 formation is analyzed. Chapter II discusses the various methods for quantifying yields of ammonia. Along with a historical perspective on the popular indophenol method, the challenges and best conditions for measuring NH3 in the Fe-DMeOPrPE system are defined.
Chapter III explores a series of trans-hydrido intermediates along a potential protonation pathway of Fe(DMeOPrPE)2N2. The complete series of reduced dinitrogen ligands (N2, N2H2, N2H4, and NH3) on the Fe(DMeOPrPE)2H+ scaffold is described. Chapter IV highlights the discovery and characterization of a unique bridged Fe(I) dimer, observed during the protonation of Fe(DMeOPrPE)2N2 as a dark purple intermediate.
Chapter V describes the electrochemistry of certain intermediates in the Fe-DMeOPrPE system. This insight should open new avenues for future investigations. By altering the electronics of the system, more NH3 may eventually be produced. Chapter VI provides a summary of this work.
This dissertation includes previously published and unpublished co-authored material.10000-01-01
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Slusher, Darlene L. "Techniques for measuring pernitric acid, peroxyacyl nitrates, and dinitrogen pentoxide by chemical ionization mass spectrometry". Diss., Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04082004-180418/unrestricted/slusher%5fdarlene%5fl%5f200312%5fphd.pdf.
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Leblanc, Ureña Humberto Antonio. "Evaluation of Inga spp. for dinitrogen fixation and nitrogen release in humid-tropical alley cropping /". free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p3137724.
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Hanisch, Friedrich. "Heterogeneous reactions of nitric acid and dinitrogen pentoxide on mineral dust surfaces a Knudsen reactor study /". [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=962060720.
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Fallah, Hengameh. "Reductive Functionalization of 3D Metal-Methyl Complexes and Characterization of a Novel Dinitrogen Dicopper (I) Complex". Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc984200/.
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Reductive functionalization of methyl ligands by 3d metal catalysts and two possible side reactions has been studied. Selective oxidation of methane, which is the primary component of natural gas, to methanol (a more easily transportable liquid) using organometallic catalysis, has become more important due to the abundance of domestic natural gas. In this regard, reductive functionalization (RF) of methyl ligands in [M(diimine)2(CH3)(Cl)] (M: VII (d3) through CuII (d9)) complexes, has been studied computationally using density functional techniques. A SN2 mechanism for the nucleophilic attack of hydroxide on the metal-methyl bond, resulting in the formation of methanol, was studied. Similar highly exergonic pathways with very low energy SN2 barriers were observed for the proposed RF mechanism for all complexes studied. To modulate RF pathways closer to thermoneutral for catalytic purposes, a future challenge, paradoxically, requires finding a way to strengthen the metal-methyl bond. Furthermore, DFT calculations suggest that for 3d metals, ligand properties will be of greater importance than metal identity in isolating suitable catalysts for alkane hydroxylation in which reductive functionalization is used to form the C—O bond. Two possible competitive reactions for RF of metal-methyl complexes were studied to understand the factors that lower the selectivity of C—O bond forming reactions. One of them was deprotonation of the methyl group, which leads to formation of a methylene complex and water. The other side reaction was metal-methyl bond dissociation, which was assessed by calculating the bond dissociation free energies of M3d—CH3 bonds. Deprotonation was found to be competitive kinetically for most of the 1st row transition metal-methyl complexes (except for CrII, MnII and CuII), but less favorable thermodynamically as compared to reductive functionalization for all of the studied 1st row transition metal complexes. Metal-carbon bond dissociation was found to be less favorable than the RF reactions for most 3d transition metal complexes studied. The first dinitrogen dicopper (I) complex has been characterized using computational and experimental methods. Low temperature reaction of the tris(pyrazolyl)borate copper(II) hydroxide {iPr2TpCu}2(µ-OH)2 with triphenylsilane under a dinitrogen atmosphere gives the µ -N2 complex, {iPr2TpCu}2(µ -N2). X-ray crystallography reveals an only slightly activated N2 ligand (N-N: 1.111(6) Å) that bridges between two iPr2TpCuI fragments. While DFT studies of mono- and dinuclear copper dinitrogen complexes suggest a weak µ-backbonding between the d10 CuI centers and the N2 ligand, they reveal a degree of cooperativity in the dinuclear Cu-N2-Cu interaction.
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Tsai, Yi-Chou 1969. "Complexation, coupling, and cleavage of organonitriles, alkynes, dinitrogen, hydrostannanes or phosphines by three-coordinate molybdenum(III) complexes". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8362.
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Bai, Guangcai. "New methods for the syntheses of amido, imido, nitrido and dinitrogen metal complexes and organometallic hydrides and oxides". Doctoral thesis, [S.l.] : [s.n.], 2001. http://webdoc.sub.gwdg.de/diss/2002/bai/bai.pdf.
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Smythe, Nathan Christopher. "Vanadium and chromium complexes supported by sterically demanding ligands : studies relevant to the reduction of dinitrogen to ammonia". Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/37838.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2006.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Vita.
Includes bibliographical references.
Chapter 1. Using the [HIPTN3N]3- ligand ([HIPTN3N]3- = [(HIPTNCH2CH2)3N]3-; HIPT = 3,5-(2,4,6-i-Pr3C6H2)2C6H3 = HexaIsoPropylTerphenyl), green paramagnetic [HIPTN3N]V(THF) (1) can be prepared from VCl3(THF)3. Reduction of 1 with potassium graphite in ethereal solvents yields a highly sensitive red solution identified as containing paramagnetic {[HIPTN3N]VN2}-(2) via infrared spectroscopy. 1 also reacts with ammonia to form bright green paramagnetic [HIPTN3N]V(NH3) (5), 2-methylaziridine to form red diamagnetic [HIPTN3N]V=NH (7), azidotrimethylsilane to form orange diamagnetic [HIPTN3N]V=N(SiMe3) (9), propylene oxide to form purple diamagnetic [HIPTN3N]V=O (11), elemental sulfur to form dark green diamagnetic [HIPTN3N]V=S (10), and carbon monoxide to form red-gold [HIPTN3N]V(CO) (12). X-Ray crystal structures were obtained for 1, 5, and the decomposition product [HIPTN3N]VH. 5 could be converted to 7 by oxidation/deprotonation using [FeCp2]OTf/(Me3Si)2NLi. The anionic nitride "{[HIPTN3N]V=N}-" could not be obtained through deprotonation of 7, removal of the -SiMe3 group from 9, or the reaction of 1 with azides. Addition of potassium graphite to 5 resulted in decomposition rather than the formation of 2. Under the catalytic conditions used for the [HIPTN3N]Mo system, 1 produced no ammonia, while 2 and 7 yielded 0.2 and 0.78 equivalents respectively.
(cont.) Chapter 2. Four dianionic diamidoamine-donor based ligands were synthesized. Two were based on a pyridine donor arm 2-(C5H4N)CH2N(CH2CH2NHIPT)2]2- ([Pyrl]2-) and 2-(6-MeC5H3N)CH2N(CH2CH2NHIPT)2]2- ([Myrl]2-), one was based on an oxygen donor arm (3,5-Me2C6H3)OCH2CH2N(CH2CH2NHIPT)2]2- ([NNO]2-), and one was based on a sulfur donor arm [(3,5-Me2C6H3)SCH2CH2N(CH2CH2NHIPT)2]2- ([NNS]2-) where HIPT = 3,5-(2,4,6-i-Pr3C6H2)2C6H3. The reaction between H2[Pyrl] with VCl3(THF)3 yielded an unstable orange product believed to be dimeric. Using H2[Myrl] yielded a stable product that on reduction with potassium graphite generated what is believed to be a dimeric, bridging dinitrogen complex, which was not catalytically active under the conditions used for the [HIPTN3N]Mo system. The reaction between VCl3(THF)3 and H2[NNO] yielded {[NNO]VCl}2 (32), which underwent ligand decomposition upon reduction with potassium graphite (33) or attempted alkylation with di-neopentyl magnesium (34). Ligand decomposition was also observed in the reaction of H2[NNS] with VCl3(THF)3 (35). X-Ray crystal structures were obtained for 32, 33, 34, and 35.
(cont.) Chapter 3. Red-black [HIPTN3N]Cr (1) can be prepared from CrCl3 ([HIPTN3N]3- = [(HIPTNCH2CH2)3N]3-, while green-black [HIPTN3N]Cr(THF) (2) can be prepared from CrCl3(THF)3 where HIPT = 3,5-(2,4,6-i-Pr3C6H2)2C6H3 = exaIsoPropylTerphenyl). Reduction of {1-2} (which means either 1 or 2) with potassium graphite in diethyl ether at room temperature yields [HIPTN3N]CrK (3) as a yellow-orange powder. There is no evidence that dinitrogen is incorporated into 1, 2, or 3. Compounds that can be prepared readily from {1-2} include red [HIPTN3N]CrCO (4), blood-red [HIPTN3N]CrNO (6), and purple [HIPTN3N]CrCl (7, upon oxidation of {1-2} with AgCl). The dichroic (purple/green) Cr(VI) nitride, [HIPTN3N]CrN (8) was prepared from Bu4NN3 and 7. X-ray studies have been carried out on 4, 6, and 7, and on two co-crystallized compounds, 7 and [HIPTN3N]CrN3 (65:35) and[HIPTN3N]CrN3 and 8 (50:50). Exposure of a degassed solution of {1-2} to an atmosphere of ammonia does not yield "[HIPTN3N]Cr(NH3)" as a stable and well-behaved species analogousto [HIPTN3N](NH3). An attempt to reduce dinitrogen under conditions described for thecatalytic reduction of dinitrogen by [HIPTN3N]Mo compounds with 8 yielded a substoichiometric amount (0.8 equiv) of ammonia, which suggests that some ammonia is formedfrom the nitride, but none is formed from dinitrogen.
(cont.) Chapter 4. TRAP (P(CH2CH2NH2)3), a phosphine containing analogue to TREN (N(CH2CH2NH2)3) was synthesized from PH3, but suitable conditions for arylation of the amine arms could not be found. Using the "pre-arylated" arm BrCH2CH2N(BOC)HIPT (BOC = tert-butoxycarbonyl; HIPT = 3,5-(2,4,6-i-Pr3C6H2)2C6H3) in the reaction with PH3 resulted in the isolation of H2PCH2CH2N(BOC)HIPT, but further substitution was unsuccessful. HIPTBr could be converted to HIPTNH2 using benzophenone imine and a rac-BINAP (2,2'-bis(diphenylphosphino)-1,1'-binaphthyl) supported Pd catalyst in preparation for DCC (dicyclohexylcarbodiimide) mediated coupling to tris-(3-propylcarboxylicacid)phosphine.
by Nathan Christopher Smythe.
Ph.D.
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Cardini, Ulisse [Verfasser], Christian [Akademischer Betreuer] Wild i Nicole [Akademischer Betreuer] Dubilier. "Dinitrogen fixation in coral reef ecosystems facing climate change / Ulisse Cardini. Gutachter: Christian Wild ; Nicole Dubilier. Betreuer: Christian Wild". Bremen : Staats- und Universitätsbibliothek Bremen, 2015. http://d-nb.info/107230371X/34.
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