Dissertations / Theses: 'Carbenes (Methylene compounds)'

1

Moeng, Mmushi Moses. "Terthienyl carbene complexes." Diss., Pretoria : [s.n.], 2001. http://upetd.up.ac.za/thesis/available/etd-02092006-153600/.

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2

Lu, Xiaosong. "Generation and reactions of aryloxy and diaryloxycarbenes /." *McMaster only, 2001.

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3

Frankowski, Kevin J. "Carbenes and carbenoids as powerful tools in organic synthesis." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 2.18 Mb., 94 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3205422.

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4

Merkley, Nadine. "Carbenes and radicals from benzyloxy [delta]3-1,3,4-oxadiazolines /." *McMaster only, 2001.

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Thesis (Ph.D.) -- McMaster University, 2001.
[Delta] in title is a Greek letter. The number 3 in title is superscript. Includes bibliographical references (leaves 147-162). Also available via World Wide Web.

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5

El-Saidi, Manal M. T. "Synthesis and thermolysis of 2,2-dioxy-5,5-dimethyl-[delta three]-1,3,4-oxadiazolines : dioxycarbenes and their reactions /." *McMaster only, 1996.

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6

Couture, Philippe. "Syntheses and reactions of aminooxycarbenes from thermolysis of [Delta3]-1,3,4-oxadiazolines /." *McMaster only, 1997.

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7

Lian, Yiqian. "Chromium and iron organometallics in organic synthesis synthetic studies toward total synthesis of taxol and chromium to iron transfer processes /." Diss., Connect to online resource - MSU authorized users, 2006.

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8

Asay, Matt J. "Ylides stabilization of novel, low valent carbon-based ligands with applications in catalysis /." Diss., [Riverside, Calif.] : University of California, Riverside, 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3350076.

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Thesis (Ph. D.)--University of California, Riverside, 2009.
Includes abstract. Title from first page of PDF file (viewed Mar. 8, 2010). Includes bibliographical references. Issued in print and online. Available via ProQuest Digital Dissertations.

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9

Rafael, Christopher Carlos Ferreira. "Synthesis of chromium carbene scaffolds for use in medicinal chemistry." Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1010863.

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This study involves using methyllithium to synthesize Fischer carbene complexes as precursors for metal templated α,β-unsaturated complexes with potential as acceptors in the Baylis Hillman reaction as well as in Dötz benzannulation. Fischer carbene complexes contain low oxidation state metal centers, are electrophilic in nature and are stabilized by π-donating substituents such as alkoxy and amino groups. The increased electron withdrawing nature of the metal carbonyl moiety was expected to improve the rates of reaction compared to organic carbonyls. Four Fischer carbenes were synthesized via nucleophilic addition of MeLi to chromium and tungsten hexacarbonyl at low temperatures followed by alkylation using either a Meerwein salt (Me₃OBF₄) to give the desired Fischer metal methyl methoxy carbenes or Et₄NBr/alkylhalide to make the corresponding ethoxy and allyloxy carbenes. Characterization was by means of ¹³C NMR, ¹H NMR, and IR. In silico studies were carried out looking at the effect of substituents on the carbene bond. Synthesis of α,β-unsaturated complexes was effected via the aldol condensation route and found to be unfavorable using enolizable aldehydes, although the use of two aryl aldehydes resulted in successful preparation of two α,β-unsaturated complexes. Difficulty in the purification of these complexes hindered their full characterization. Computational studies looked at the effect of substituents on the system as well as variation of the metal from Cr to Mo and W. Synthesis of Baylis Hillman adducts using α,β-unsaturated complexes as acceptors was unsuccessful due to the ease of product oxidization. One potential product was obtained in its crude form although purification was not possible due to oxidation. Computational studies suggested that the oxygen on the ligand negatively impacts the stability of these Fischer carbene derived Baylis Hillman adducts promoting intramolecular oxidation of the metal. The α,β-unsaturated complexes and Baylis Hillman adducts were considered to be candidates to undergo Dötz benzannulation methodology. The use of the α,β-unsaturated complexes in this reaction was generally unsuccessful, both in the microwave and in conventional reflux conditions. Computational studies of these compounds were carried out to facilitate understanding of their stability and configuration.

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10

Olivier, Andrew John. "Novel carbene complexes with pyrrole ligands." Diss., Pretoria : [s.n, 2001. http://upetd.up.ac.za/thesis/available/etd-02242006-125303/.

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11

Bruno, Deborah Suzanne. "Synthesis and thermal decomposition of [CM(CO)CH₂S(Ph)CH₂CH=CH₂] BF₄, M=Fe, Ru." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/27663.

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12

Chu, Wai-kin, and 朱煒堅. "Syntheses, spectroscopy and photophysics of ruthenium(II) carbene complexes and diimine complexes with functionalized ligands formolecular recognition and organized assembly." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31240082.

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13

Wang, Jian. "Heteroaryl(trifluoromethyl)carbenes and related strained cumulenes under matrix isolation conditions." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3289461.

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14

Julius, Gerrit Richard. "New transition metal carbene complexes for application in homogeneous catalysis /." Link to the online version, 2005. http://hdl.handle.net/10019/1063.

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15

Etogo, Anthony O. "Late transition metal chemistry of imidazole-based N-heterocyclic carbene ligands synthesis, characterization and luminescence /." abstract and full text PDF (free order & download UNR users only), 2006. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3209961.

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16

Angrish, Deepshikha. "Catalytic transformations via metallocarbenes." Thesis, University of Oxford, 2007. http://ora.ox.ac.uk/objects/uuid:dd93e21b-7e8a-44dc-b2f5-49fc670e065c.

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This thesis describes a new catalytic activity of a commonly used metathesis catalyst and demonstrates the viability of directly coupling two powerful C-C bond forming strategies: cross-metathesis and ylide transformations, both proceeding via metal-catalysed carbene transfer. Catalytic C-C bond formation reactions are highly significant; my studies focus on such transformations involving metallocarbenes. Grubbs' 2^nd generation Ru catalyst is the most commonly used catalyst in olefin metathesis to generate thermodynamically preferred trans-olefms. During the course of my studies, I established that Grubbs 2^nd generation catalyst (0.5 mol%) can also dimerise diazoacetates to give cis-enediesters (maleates) in good to excellent yields (74-99%) with high stereoselectivity (Z:E>95:5). The reaction between two different diazoacetates, catalysed by Grubbs catalyst gave access to unsymmetrical cis-enediesters with high stereoselectivity (Z:E>95:5, generally 99:1). The catalyst was found to retain its alkene metathetical activity during diazo coupling; building on this latter observation a novel route to access dienyl dilactones by head-to-head dimerisation of unsaturated diazoacetates was developed. Cross-metathesis was found to be chemoselective in the presence of diazo functionality (when flanked by two carbonyl groups), allowing the functionalisation of tethered olefin. The elaborated diazocarbonyl olefms were subjected to Rh₂(OAc)₄ catalysed ylide formation and subsequent transformations. Significantly, one-pot cross-metathesis/ylide transformations (1,3-dipolar cycloaddition and [2,3]-simgatropic rearrangement) also proved to be viable, establishing that the spent Ru catalyst following metathesis does not affect the subsequent Rh(II)-catalysed transformation.

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17

Quezada, Carol A. "N-Heterocyclic Carbenes: From Heterocyclynes to Potential Radiopharmaceuticals." Akron, OH : University of Akron, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1116249871.

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18

Duan, Gongping. "Design, synthesis, and photophysics and photochromic study of dithienylethene-containing heterocyclic derivatives and N-heterocyclic carbene-ruthenium (II) complexes." Click to view the E-thesis via HKUTO, 2010. http://sunzi.lib.hku.hk/hkuto/record/B44248246.

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19

Au, Ka-man, and 區嘉雯. "Luminescent cyclometalated gold (III) complexes with ancillary N-heterocyclic carbene and alkynyl ligands : from design, synthesis, photophysics to supramolecular assembly and functions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hdl.handle.net/10722/207995.

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A library of luminescent cyclometalated gold(III) complexes containing various bis-cyclometalating R-C^N^C ligands derived from 2,6-diphenylpyridine and ancillary alkynyl ligands, [Au(R-C^N^C)(C≡CR’)], has been synthesized. Some of the complexes have been structurally determined by X-ray crystallography. These complexes were found to exhibit intense emission in dichloromethane solution at 298 K, originating from metal-perturbed triplet intraligand (IL) excited states of the R-C^N^C ligand, with substantial charge transfer character from the aryl moiety to the pyridyl ring. In the presence of electron-rich alkynyl ligands, the emission origin could be switched to an alkynyl-to-cyclometalating ligand ligand-to-ligand charge transfer (LLCT) excited state. This class of complexes was also demonstrated to show rich electroluminescence properties as emitters in organic light-emitting devices. In addition, the supramolecular assembly of this class of complexes has also been revealed in gelation studies. N-Heterocyclic carbenes have been incorporated into the gold(III) metal center to prepare a series of luminescent mononuclear and dinuclear gold(III) complexes, [{Au(C^N^C)}n(NHC)](PF6)n and [{Au(tBuC^N^CtBu)}n(NHC)]- (PF6)n (n = 1, 2). The X-ray crystal structures of most of the complexes have been determined. The emissions of these complexes were assigned to originate from the metal-perturbed intraligand excited state of the bis-cyclometalating ligand. One of the C2-bridged dinuclear complexes was found to exhibit two distinct reduction couples, tentatively correlated to the presence of significant intramolecular π-π interaction in the complex. Two novel series of luminescent mononuclear alkynylgold(III) complexes, [Au(C^N)(C≡CR)2] (HC^N = 2-phenylpyridine (Hppy) and derivatives) and [Au(C^N^N)(C≡CR)]PF6 (HC^N^N = 6-phenyl-2,2’-bipyridine and derivatives), have been synthesized. Some of the X-ray crystal structures have been determined. The former class of complexes with bidentate C^N ligands has been observed to show tunable emission spanning across the visible spectrum from 462 to 697 nm. With the exception of [Au(ppy)(C≡C-C6H4-NH2-p)2] which showed a low-energy band originated from a 3LLCT [π(C≡C-C6H4-NH2)→π*(C^N)] excited state, all complexes exhibited vibronic-structured emission bands originated from the intraligand transition of the cyclometalating C^N ligand in dichloromethane solution at 298 K. On the other hand, most of the complexes with the tridentate C^N^N-type ligand have been observed to exhibit vibronic-structured emission bands attributed to the intraligand transition of the C^N^N ligand in low-temperature butyronitrile glass.
published_or_final_version
Chemistry
Doctoral
Doctor of Philosophy

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20

Tian, Weiwei. "Rhodium-mediated carbene insertion synthesis of (-)-hamigeran B and the (-)-sordaricin core /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 119 p, 2008. http://proquest.umi.com/pqdweb?did=1609287781&sid=2&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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21

Meyer, Annalene. "The synthesis of α-alkoxy and α-aminostannanes as precursors to Novel Chromium Fischer Carbenes." Thesis, Rhodes University, 2012. http://hdl.handle.net/10962/d1005036.

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The present study involves the use of main group organometallics: organostannanes and organolithiums as precursors to chromium Fischer carbene complexes. Fischer carbenes are well stabilized by the π‐donor substituents such as alkoxy and amino groups and low oxidation state metals such as Group 6 (Chromium, Molybdenum or Tungsten). Carbenes are an important intermediate in the synthesis of a range of compounds through cyclopropanations, insertions, coupling and photochemical reactions. Synthesis and successful characterisation of three α‐alkoxystannanes was achieved via nucleophilic addition of tributylstannyllithium to the respective aldehydes, followed by an immediate MOM protection of the resulting alcohol. Six α‐aminostanannes were synthesised, consisting of N‐BOC, N‐acetyl and N‐ethyl derivatives of pyrrolidine and piperidine, via α‐lithiation and subsequent tinlithium transmetallation in the presence of TMEDA. The ¹³C NMR analysis highlighted an interesting phenomenon of tin‐carbon coupling that revealed unique structural information of both types of stannanes. DFT analysis was completed on the series of stannanes; a predicted frequency analysis was obtained which complemented the experimental Infra‐red data in elucidation of the compounds. The α‐alkoxy and α‐aminostannanes provided stable precursors to the organolithiums required for the synthesis of the novel Fischer chromium carbenes. The organolithiums were obtained via tinlithium exchange at low temperatures, followed by the addition of chromium hexacarbonyl to form the acylpentacarbonyl‐chromate salt. Alkylation of this intermediate using a Meerwein salt, Me₃OBF₄, gave rise to the novel Fischer chromium carbene complexes. Fischer chromium carbenes derived from the two isomeric butyl and isobutyl stannanes and the two N‐ethyl α‐aminostannanes were successfully synthesised. The difficulty encountered in the purification of the Fischer carbene complexes hindered the full characterisation, due to the presence of a by‐product, tetrabutyltin.

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22

Stander, Elzet. "Nuwe reaksies van gedeprotoneerde Fischer-tipe karbeenkomplekse." Thesis, Link to the online version, 2005. http://hdl.handle.net/10019/1222.

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23

Hesler, Valerie Jane. "N-Heterocyclic carbene-metal complexes derived from imidazolium-linked cyclophane and biimidazolium salts." University of Western Australia. School of Biomedical, Biomolecular and Chemical Sciences, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0088.

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This thesis presents an investigation into the synthesis of metal complexes of (Nheterocyclic carbene)-based cyclophanes. There were three main areas of focus: synthesis and complexation of bis(4,5-dihydroimidazolium) salts; the synthesis and complexation of phenol-functionalised imidazolium cyclophanes; and the synthesis and complexation of (N-heterocyclic carbene)-based cyclophanes by C-C bond activation of biimidazolium salts with electron-rich metals. The synthesis of xylyl-linked bis(4,5-dihydroimidazolium) salts was investigated. Attempts to prepare these compounds by the cyclisation of a tetraamine (linear or macrocyclic) were unsuccessful due difficulties in preparing the tetraamines. The target compounds could be prepared by adapting the methods developed for the synthesis of bis(imidazolium) salts however problems associated with purification and stability of the products prevented complexation studies. A series of phenol-, phenoxide- and anisole-functionalised imidazolium cyclophanes were prepared. Their structural properties were investigated using dynamic nmr studies and X-ray crystallography. Complexation of the functionalised cyclophanes was investigated. The phenol cyclophane I formed a dinuclear complex with mercury(II). This complex is the first example of a complex derived from a phenol-functionalised imidazolium cyclophane. However the anisole cyclophane II and the unsymmetrical phenol/ortho cyclophane III were unable to form complexes possibly due to steric hindrance and instability of the cyclophane respectively. Preliminary complexation studies of the bis(imidazolium)phenol V suggested that complexation with palladium(II) and mercury(II) were possible but more work is required to determine the optimum reaction conditions. A series of biimidazolium salts VI (both new and known) were prepared. Previously reported biimidazolium salts have very low solubility in common solvents therefore the incorporation of long alkyl chains to the bridging group was investigated as a means to improve the solubility. The structure of the salts was explored using a range of techniques including dynamic nmr spectroscopy, cyclic voltammetry, UV/Visible spectroscopy, X-ray crystallography and mass spectrometry. Some of the biimidazolium salts were able to rotate about the C2-C2' bond and the free energy of activation for this process was estimated using dynamic nmr studies. C-C bond activation of the biimidazolium salts with palladium(0) was used to form a series of palladium(II) complexes (VII) of (NHC)-based cyclophanes. These reactions are the first examples of the synthesis of bis(NHC) complexes by C-C bond activation. The reactivity of the biimidazolium salts with palladium(0) was compared to their solution structure and it was found that only the biimidazolium that were able to rotate about the C2-C2' bond could react with palladium(0).

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24

Baba, Eduard. "N-Heterocyclic Carbenes of the Late Transition Metals: A Computational and Structural Database Study." Thesis, University of North Texas, 2005. https://digital.library.unt.edu/ark:/67531/metadc4792/.

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A computational chemistry analysis combined with a crystallographic database study of the bonding in late transition metal N-heterocyclic carbene (NHC) complexes is reported. The results illustrate a metal-carbon bond for these complexes, approximately 4% shorter than that of a M-C single bond found in metal alkyl complexes. As a consequence of this result, two hypotheses are investigated. The first hypothesis explores the possibility of multiple-bond character in the metal-carbon linkage of the NHC complex, and the second, considers the change in the hybridization of the carbenoid carbon to incorporate more p character. The latter hypothesis is supported by the results. Analysis of these complexes using the natural bond orbital method evinces NHC ligands possessing trans influence.

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25

Lam, Sze-kui. "An asymmetric carbene cyclization cycloaddition strategy toward the synthesis of indicol." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B36631863.

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26

Aksın, Özge Artok Levent. "The activity of silica immobilized palladium N-heterocyclic carbene complexes toward Mizoro-Heck reaction and their characterization/Özge Aksın;thesis advisor Levent Artok." [s.l.]: [s.n.], 2005. http://library.iyte.edu.tr/tezler/master/kimya/T000341.pdf.

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Thesis (Master)--İzmir Institute of Technology, İzmir, 2005.
Keywords: Palladium, Immobilization, Heck Reaction, Palladium-N-Heterocyclic Carbene, Carbon-Carbon Coupling. Includes bibliographical references (leaves. 89-104).

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27

Truscott, Byron John. "The design and synthesis of multidentate N-heterocyclic carbenes as metathesis catalyst ligands." Thesis, Rhodes University, 2011. http://hdl.handle.net/10962/d1004962.

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This study has focused on the design and preparation of bi– and tridentate N–Heterocyclic Carbene (NHC) ligands in order to investigate the effect of a multidentate approach to the formation, stability and catalytic activity of coordination complexes. Chapters 1 – 3 provide background information of relevant catalysis, carbene and coordination chemistry, followed by previous work performed within our research group. In Chapter 4 attention is given to the synthetic aspects of the research conducted, comprising two distinct approaches to the preparation of unsymmetrical saturated and unsaturated NHCs. Firstly, an investigation of the saturated NHC ligands yielded three novel, unsymmetrical pro–ligands, viz., two halopropyl imidazolinium salts and a bidentate hydroxypropyl imidazolinium salt. Secondly, eight imidazolium salts have been generated, including a hydroxypropyl analogue and novel decyl and tridentate malonyl derivatives. These compounds were prepared using microwave–assisted methodology for the alkylation of N– mesitylimidazole – an approach that drastically reduced reaction times (from 8 hours – 7 days to ca. 0.5 – 2 hours) and facilitated isolation of the imidazolium salts. Many of the compounds prepared in this study are novel and were fully characterized using HRMS and 1– and 2–D NMR analysis. Coordination studies using a selection of the prepared pro–ligands afforded an alkoxy–NHC silver derivative and four novel Ru–complexes, viz., Grubbs II–type Ru–complexes containing:– chloropropyl imidazolinylidene; propenyl imidazolylidene; and bidentate alkoxypropyl imidazolylidene ligands. Furthermore, a well–defined benzyl mesitylimidazolylidene Ru–complex has been isolated, which exhibited good stability in air. DFT–level geometry–optimization studies, using the Accelrys DMol3 package have given valuable insights into the likely geometries of the prepared and putative catalysts.

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28

Annapureddy, Raja Sekarreddy. "Ruthenium porphyrin catalyzed carbene mediated C-H insertion and cycloaddition reactions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/206316.

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29

Moore, Adam L. "N-heterocyclic carbenes with pendant arylamine donor substituents as supports for metal-metal interactions of closed shell metal ions." abstract, 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3326620.

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30

Zhou, Congying. "Ruthenium porphyrins and dirhodium (II, II) carboxylates catalyzed ylide-mediated cycloadditions and carbenoid transfer reactions." Click to view the E-thesis via HKUTO, 2004. http://sunzi.lib.hku.hk/hkuto/record/B31046484.

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31

Dupuy, Stéphanie. "N-heterocyclic carbene gold hydroxide complexes as bond activation reagents." Thesis, University of St Andrews, 2014. http://hdl.handle.net/10023/6613.

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Although known since the 1930s, organogold chemistry has been dormant until recently, primarily due to preconceptions about the inertness of gold in transformations. However, this last decade has witnessed the emergence of a Golden Age with the development of a wealth of reports on gold in a plethora of reactions. In recent years, the drive for more atom- and step-economical and environmentally friendly reactions has become a field of intense research. In our on-going research on well-defined transition metal complexes bearing NHC ligands, our group recently discovered a new gold(I) hydroxide complex [Au(OH)(IPr)] (1a) that can be easily synthesised from the chloride precursor [AuCl(IPr)] (1b). A preliminary survey of the reactivity of this gold synthon has demonstrated interesting reactivity that holds great potential in bond activation reactions and the development of useful synthetic methods. Simplistically, this gold hydroxide complex can be seen as a strong Brønsted base. This thesis is dedicated to an in-depth examination of the reactivity of this complex in base-free bond activation reactions. Two themes predominate in the following chapters: the first part demonstrates the activity of gold(I) hydroxide as a bond activation agent to readily and efficiently access organogold complexes while the second part studies the reactivity of this compound in decarboxylation processes with carboxylic acids. Chapter 2 and 3 were dedicated to the development of new synthetic routes to access organogold complexes via base-free transmetalation reactions with organoborons and silanes using 1a. The combination of experimental and computational studies allowed identification and isolation of key intermediates in these reactions. Chapter 4 can be seen as a transition between the development of novel methodologies to synthesise aryl and heteroarylgold complexes and the first steps of gold hydroxide 1a as mediator in decarboxylation reaction. As a result, a novel mode of reactivity for gold was discovered and the synthetic route developed constitutes one of the greenest procedures to prepare organogold complexes with the generation of water and CO₂ as only side products. Chapter 5 and 6 venture further into the exploration of 1a in decarboxylation reactions and detail the development of a catalytic process for the protodecarboxylation reaction and subsequent mechanistic investigations of this reaction through stoichiometric experiments and kinetic and computational studies.

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32

Zinser, Caroline Magdalene. "Palladium and gold N-heterocyclic carbene complexes : synthesis and catalytic applications." Thesis, University of St Andrews, 2019. http://hdl.handle.net/10023/17066.

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33

Makanjee, Che Azad. "An experimental and theoretical investigation of unstable Fischer chromium carbene complexes." Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1002953.

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This organometallic study involves the use organostannanes and organolithiums as precursors to chromium Fischer carbene complexes. Fischer carbenes are typically electrophilic and are stabilized by a single π-donor substituent, and contain low oxidation state metals (often but not always from Group 6). They are highly reactive and can give access to a range of biologically active compounds through cyclopropanations, insertions, coupling and photochemical reactions. Synthesis and characterization of three MOM-protected α-alkoxy organostannanes was successfully carried out via a nucleophilic addition of tributylstannyllithium to suitable aldehydes, and immediate protection of the alcohol with MOM. Two N-BOC protected α-amino organostannanes were successfully synthesized and characterized via α-lithiation and tin-lithium exchange in the presence of TMEDA. Tin-lithium transmetallation of the organostannanes allowed access to the organolithiums required for the synthesis of novel Fischer carbenes. Addition of chromium hexacarbonyl to the organolithiums formed the acylpentacarbonyl chromate salt which was alkylated with Meerwein salt, resulting in the Fischer carbene and a by-product, tetrabutyltin, which proved difficult to remove. Several Fischer carbenes were synthesized and characterized, some simple and known and some novel. In silico work explored the reaction coordinate of the [2+2] cycloaddition towards the formation of β-lactams, and the photoactivation cycle that precedes this process. Computational work also showed the effect of the ligand on the stability and reactivity of the carbene. It was found that in some cases the oxygen on the ligand could negatively influence the stability of the carbene (when compared to a simple methyl carbene). A link between bond orders and back donation in Fischer carbenes was explored in an attempt to theoretically predict the stability of a range of carbenes.
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34

Pezacki, John Paul. "Rate constants and mechanisms for reactions of carbenes and cations from oxadiazolines and other precursors /." *McMaster only, 1998.

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35

Li, Yan, and 李艷. "Synthesis and reactivity of carbene complexes of iron, ruthenium and osmium porphyrins." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31245730.

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36

Polshakov, Dmitrii Arkadyevich. "Ultrafast spectroscopy and dynamics of nitrenes and carbenes." Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1130968887.

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37

Zhou, Congying, and 周聰穎. "Ruthenium porphyrins and dirhodium (II, II) carboxylates catalyzed ylide-mediated cycloadditions and carbenoid transfer reactions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31046484.

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38

Zou, Taotao, and 邹滔滔. "Anti-cancer N-heterocyclic carbene complexes of gold(III), gold(I) and platinum(II) : thiol "switch-on" fluorescent probes, thioredoxin reductase inhibitors and endoplasmic reticulum targeting agents." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2015. http://hdl.handle.net/10722/208614.

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39

Du, Toit Aletta. "Anioniese Fischer-tipe karbeenkomplekse as ligande." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53280.

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40

Du, Toit Maria. "Nuwe karbeenkomplekse en die 'kompleks van komplekse' konsep in ligandontwerp." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53530.

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41

Lam, Sze-kui, and 林詩鉅. "An asymmetric carbene cyclization cycloaddition strategy toward the synthesis of indicol." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B36631863.

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42

Duan, Gongping, and 段公平. "Design, synthesis, and photophysics and photochromic study of dithienylethene-containing heterocyclic derivatives and N-heterocycliccarbene-ruthenium (II) complexes." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B44248246.

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43

Kruger, Anneke. "N-heterosikliese karbeenkomplekse van groep 10 metale : nuwe moontlikhede." Thesis, Stellenbosch : Stellenbosch University, 2007. http://hdl.handle.net/10019.1/19636.

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Thesis (MSc)--University of Stellenbosch, 2007.
ENGLISH ABSTRACT: This study comprises the synthesis and characterisation of N-heterocyclic carbene complexes of group 10 metals with the main focus on such complexes with the nucleophilic N-atom in a position further than the α-position from the carbene carbon atom. These compounds were synthesised by the initial alkylation of quinoline- and acridine derivatives followed by the oxidative addition of the resulting salts to the complexes M(PPh3)4 (M = Ni, Pd, Pt). To complete the study an investigation of the catalytic activity and stability of such compounds in C,C-coupling catalysis was conducted. The carbene ligands used differed with respect to the position of the N-atom relative to the carbene carbon atom as well as with respect to substituents. The oxidative addition of the quinolinium- and acridiniumchloride salts to Ni(PPh3)4 was initially problematic. The desired product formed only in small amounts and could not be isolated easily. However, by replacing toluene with more polar THF as solvent, the nickel complexes could be synthesised in high yield without any indication of decomposition. Oxidative addition to Pt(PPh3)4 also yielded the desired product, although a number of by-products were formed as well. The molecular structure of trans-chloro(1,3-dimethyl-1,2-dihydroquinoline-2-ylidene)-bis(triphenylphosphine) platinum(II) trifluoromethanesulfonate could nevertheless be determined by X-ray crystallography. The new one-N, six membered, heterocyclic carbene complexes were all unambiguously characterised by NMR spectroscopy, mass spectrometry and X-ray crystallography. The carbene character of the complexes was corroborated by a large downfield chemical shift (δ 203 – 230) of the carbene carbon atoms in their 13C NMR spectra. The analyses furthermore indicated that with the exception of cis-chloro(1-methyl-3-phenyl-1,4-dihydroquinoline-4- ylidene)bis(triphenylphosphine)palladium(II) hexafluorophosphate, all the palladium, nickel and platinum complexes exhibit a trans arrangement of the PPh3 ligands. Both the cis- and the trans isomers of the complexes, chloro(1,3-dimethyl-1,2-dihydroquinoline-2-ylidene)- bis(triphenylphosphine)palladium(II) tetrafluoroborate and chloro-(1,3-dimethyl-1,2-dihydroquinoline- 2-ylidene)bis(triphenylphosphine)palladium(II) trifluoromethanesulphonate are, however, present in solution. The molecular structure of both isomers were determined by Xray crystallography. Crystallographic studies revealed that the new family of cationic complexes exist in a slightly distorted square planar environment with the carbene ligand orientated almost perpendicular to this plane. The metal-carbene bond lengths are insensitive to variations in the substituents on the carbene ligands and are therefore not a suitable parameter to distinguish between the strengths of these bonds. The N-heterocyclic carbene ligands with the N-atom removed from the carbene carbon atom by three bonds, exhibit a greater trans influence in the palladium complexes than those with the N-atom in the α-position. This is an indication of the better σ-donor ability of the former. A significant difference in the Ni-Cl bond lengths could, however, not be detected. The catalytic activity of the new synthesised palladium and nickel complexes in the Mizoroki- Heck and Suzuki-Miyaura coupling reactions, were investigated. The palladium complexes tested show potential as precatalysts for the Mizoroki-Heck reaction, although relatively high temperatures were needed to effect coupling, while coupling of aryl chlorides did not occur at all. The trans-chloro(1,2-dimethyl-1,4-dihydroquinoline-4-ylidene)bis(triphenylphosphine)- palladium(II) trifluoromethanesulphonate complex also displayed high activity in the C,Ccoupling of bromofluorene with arylboronic acids in the Suzuki-Miyaura coupling reaction. It even yielded high conversions in instances where sterically hindered aryl halides were used. The trans-chloro(1,2-dimethyl-1,4-dihydroquinoline-4-ylidene)bis(triphenylphosphine)- nickel(II) trifluoromethanesulphonate complex catalyses the coupling of sterically hindered arylbromides as well as arylchlorides to arylboronic acids. By further optimising the reaction conditions and increasing the streric bulk of the carbene ligands, even better results in both the Mizoroki-Heck and the Suzuki-Miyaura reactions are expected.
AFRIKAANSE OPSOMMING: Hierdie studie behels die sintese en karakterisering van N-heterosikliese karbeenkomplekse van groep 10 metale. Daar is veral gefokus op N-heterosikliese karbeenligande waarin die nukleofiele N-atoom verder as die α-posisie vanaf van die karbeenkoolstofatoom verwyder is. Die betrokke komplekse is gesintetiseer deur die alkilering van kinolien- en akridienderivate, gevolg deur die oksidatiewe addisie van die resulterende soute aan die komplekse M(PPh3)4 (M = Ni, Pd, Pt). Om die studie af te rond is die katalitiese aktiwiteit van dié komplekse in C,C-koppelingsreaksies ondersoek. Karbeenligande wat slegs een nukleofiele stikstofatoom besit en verskil ten opsigte van die posisie van dié atoom relatief tot die karbeenkoolstofatoom asook substituente aan die ligand, is gebruik. Die oksidatiewe addisie van die kinoliniumchloried- en akridiniumchloriedsoute aan Ni(PPh3)4 het aanvanklik probleme opgelewer, sodat slegs ’n klein hoeveelheid van die verlangde produk, wat moeilik isoleerbaar was, gevorm het. Deur egter ’n meer polêre oplosmiddel, THF, in plaas van tolueen te gebruik, kon die nikkelkomplekse met goeie opbrengs en sonder enige aanduiding van ontbinding, berei word. Oksidatiewe addisie aan Pt(PPh3)4 het die verlangde produk gelewer, alhoewel ’n aantal neweprodukte ook gevorm het. Ten spyte hiervan is daarin geslaag om die molekulêre struktuur van trans-chloro(1,3- dimetiel-1,2-dihidrokinolien-2-ilideen)bis(trifenielfosfien)platinum(II) trifluorometaansulfonaat kristallografies te bepaal. Die nuwe gesintetiseerde een-N, seslid, heterosikliese karbeenkomplekse is deur KMRspektroskopie, massaspektrometrie en X-straalkristallografie eenduidig gekarakteriseer. Die karbeenkarakter van die komplekse is bevestig deur die ver veldafwaartse chemiese verskuiwing (δ 203 - 230) van die karbeenkoolstofatoom in die 13C-KMR-spektra. Die analises toon ook dat, met die uitsondering van cis-chloro(1-metiel-3-feniel-1,4- dihidrokinolien-4-ilideen)bis(trifenielfosfien)palladium(II) heksafluorofosfaat, al die palladium-, nikkel- en platinumkomplekse ’n trans-rangskikking van die PPh3-ligande besit. Die cis- sowel as die trans-isomere van die palladiumkomplekse chloro(1,3-dimetiel-1,2- dihidrokinolien-2-ilideen)bis(trifenielfosfien)palladium(II) tetrafluoroboraat en chloro(1,3- dimetiel-1,2-dihidrokinolien-2-ilideen)bis(trifenielfosfien)palladium(II) trifluorometaansulfonaat, is in oplossing teenwoordig en die molekulêre struktuur van albei isomere is kristallografies bepaal. Dit is vasgestel dat al die kationiese komplekse in ’n effens verwronge vierkantvlakomgewing, met die karbeenligand byna loodreg op dié vlak, voorkom. Die metaal-karbeenbindingslengtes is onsensitief teenoor ’n variasie in die substituente gebind aan die karbeenligande en dit is nie ’n handige parameter om tussen die sterktes van dié bindings te differensieer nie. Die N-heterosikliese karbeenligande waarvan die N-atoom in ’n posisie drie bindings van die karbeenkoolstofatoom af voorkom, toon ’n effens sterker trans-invloed as die ligande met ’n α-stikstofatoom in die palladiumkomplekse. Dit is ’n aanduiding dat eersgenoemde ligande beter σ-donor eienskappe besit. Die nikkelkomplekse verskil egter nie betekenisvol ten opsigte van hul Ni-Cl bindingslengtes nie. Die katalitiese aktiwiteit en stabiliteit van die nuwe reekse palladium- en nikkelkomplekse is in Mizoroki-Heck en Suzuki-Miyaura-koppelingsreaksies ondersoek. Ofskoon relatief hoë temperature nodig is om koppeling te bewerkstellig en die komplekse nie koppeling van ’n arielchloried met butielakrilaat kataliseer nie, toon die palladiumkomplekse tóg potensiaal as prekatalisatore in die Mizoroki-Heck-reaksie. Die kompleks, trans-chloro(1,2-dimetiel-1,4- dihidrokinolien-4-ilideen)bis(trifenielfosfien)paladium(II) trifluorometaansulfonaat, toon ook uitstekende katalitiese aktiwiteit in die C,C-koppeling van bromofluoreen met arielboorsure in die Suzuki-Miyaura-koppelingsreaksie. Hierdie kompleks kataliseer selfs die koppeling van steries gehinderde arielhaliede met arielboorsure. Die kompleks trans-chloro(1,2-dimetiel- 1,4-dihidrokinolien-4-ilideen)bis(trifenielfosfien)nikkel(II) trifluorometaansulfonaat, bemiddel koppeling van arielbromied-, sowel as steries gehinderde arielchloriedsubstrate aan arielboorsure. Selfs beter resultate in die Mizoroki-Heck- sowel as die Suzuki-Miyaurakoppelingsreaksies word verwag deur verdere optimalisering van die reaksiekondisies en die inbouing van groter steriese hindering in die ligande.

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44

Dunn, James A. "From organometallic cations to carbenes : an NMR, structural and reactivity study /." *McMaster only, 1998.

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45

Radzewich, Catherine Ellen. "Activation of small molecules by cationic rhenium complexes /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/11554.

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46

Haque, Rosenani S. M. Anwarul. "Silver, mercury and ruthenium complexes of N-heterocyclic carbene linked cyclophanes." University of Western Australia. Chemistry Discipline Group, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0236.

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This thesis describes the synthesis and isolation of silver, mercury, ruthenium and palladium complexes of bidentate N-heterocyclic carbenes (NHCs), derived from imidazolium-linked cyclophanes and related bis-imidazolium salts. The cyclophane structures contain two imidazolyl links between ortho- and meta- substituted aromatic rings and the related structures are ortho-, meta- and para-xylyl linked bis-imidazolium salts. The complexes have been characterised by NMR spectroscopy and X-ray crystallography. The synthesis of five new silver complexes has been achieved via a simple complexation reaction of the cyclophane and bis-imidazolium salts with the basic metal source Ag2O. The new silver carbene systems are thermally stable. Three of the complexes are dinuclear, cationic complexes, while two are mononuclear complexes, one cationic and one neutral. A number of mono- and di-nuclear mercury(II)-NHC complexes have been synthesised from the ortho- and meta-linked cyclophanes and the related meta-linked bis-imidazolium salts. The mercury complexes were prepared by direct mercuration method using mercury(II) acetate. The syntheses were perfomed in air and the complexes are stable to air and moisture. Mercury complexes I and II represent the first example of mononuclear metal complexes derived from meta-substituted imidazolium-linked cyclophanes. NHC-ligand transfer reactions from NHC-silver complexes and NHC-mercury complexes are described. An ortho-cyclophane ligand was successfully transfered from a silver complex to its palladium counterpart. Furthermore, palladium complex III, bearing a para-xylyl linked bis-NHC ligand, was made by transmetallation from both a silver and mercury complex. This is the first reported NHC-palladium complex of a para-xylyl linked bis-NHC ligand. A new redox transmetallation method for NHC ligand transfer, using a mercury complex, is presented. A palladium complex was made via redox transmetallation using a mercury complex of an ortho-NHC-cyclophane. A ruthenium(II)-NHC complex, IV containing an ortho-cyclophane ligand has been prepared via silver transmetallation and in situ complexation methods. In the transmetallation route, a silver complex of an ortho-cyclophane was treated with RuCl2(PPh3)3 to form IV. This complex represents the first example of a ruthenium complex bearing an NHC-cyclophane ligand, v and is also the first example of a metal complex derived from an imidazolium-linked cyclophane where the arene unit of the cyclophane is also involved in bonding to the metal centre.

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47

Stander-Grobler, Elzet. "Carbene ligand and complex design directed towards application in synthesis and homogeneous catalysis." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/1139.

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Thesis (PhD (Chemistry and Polymer Science))--Stellenbosch University, 2008.
Alkylated acetonitrile that forms during the synthesis of the sulfonium salt, [(Me3)2(MeS)S][BF4], is involved in the formation of new , -unsaturated Fischer-type carbene complexes from (CO)5M=C(OMe)CH2Li (M = Cr, W). Metal migration observed when the substitution product obtained from the reaction of the anionic carbene complexes (CO)5M=C(NMe2)CºC¯ (M = Cr, W) with Ph3PAu+ was left in solution, was also kinetically and theoretically investigated. 1H NMR and quantum mechanical (at the B3LYP level of theory) data indicated a complicated mechanism. The a,b-unsaturated Fischer-type carbene complex, (CO)5Cr=C(OMe)CH=C(Me)NH(Me), obtained from the reaction of (CO)5M=C(OMe)CH2¯ with alkylated acetonitrile, was transformed into the new remote one-N, six-membered, carbene ligand (rN1HC6) complex, (CO)5Cr=C(CH=C(Me)N(Me)CH=C(nBu). The carbene ligand unprecedentedly preferred the softer Rh(CO)2Cl moiety to the Cr(CO)5 metal fragment and transferred readily. A new series of remote and abnormal square planar compounds [r/a(NHC)(PPh3)2MCl]CF3SO3 (M = Pd or Ni) was prepared by oxidative substitution. The various positions for metal-carbon bond formation on a pyridine ring to furnish various ligand types i.e. C2 for nN1HC6, C3 for aN1HC6 or C4 for rN1HC6 received attention. The ligands were arranged in increasing order of carbene character, aNHC < nNHC < rNHC and trans influence, nN2HC5 ~ aN1HC6 ~ nN1HC6 < rN1HC6. In competitive situations, oxidative substitution occurred selectively at C4 of the pyridine ring rather than at C2 and on the aromatic ring containing the heteroatom (C4), rather than on an annealed aromatic ring (C7). Crystal and molecular structure determinations confirmed the preferred coordination sites. Quantum mechanical calculations (at the RI-BP86/SV level of theory) indicated that the chosen carbene ligand has a much larger influence than the metal on the BDE of the M-Ccarbene bond; the farther away the N-atom is from the carbene carbon, the stronger the bond. In complexes that also contain additional external nitrogen atoms, e.g. trans-chloro(N-methyl-1,2,4- trihydro-2-dimethylaminepyrid-4-ylidene)bis(triphenylphosphine)palladium(II) triflate and transchloro( N-methyl-1,2,4-trihydro-2-dimethylaminepyrid-4-ylidene)bis(triphenylphosphine)nickel(II) triflate, stabilisation originates from both the nitrogens. 2-Chloro-1-methyl-1H-pyrid-4-ylidenephenylammonium triflate afforded complexes with both remote as well as normal nitrogen atoms. New azole complexes of palladium and nickel with remote heteroatoms were also prepared from N-methyl-4',4'-dimethyl-2'-thiophen-3-chloro-2-yl-4,5-dihydro-oxazole. Employing the compound 1,5-dichloroanthraquinone, the product of a double oxidative substitution on two Pd centra could be isolated but not alkylated. The fact that the chemical shift of the metal bonded carbon in the 13C NMR spectrum can not be used as absolute measure of carbene character, was emphasised in a compound where the heteroatom was situated seven bonds away from the carbon donor. In efforts to synthesise a sulphur-bridged complex that contains carbene ligands, crystals of transdi- iodobis(1,3-dimethyl-imidazoline-2-ylidene)palladium were obtained. Bridged thiolato complexes with N1HC6 ligands were unexpectedly found in the attempt to substitute the halogen on chosen square planar carbene complexes of palladium, widening the application possibilities of N1HC6 ligands in organometallic chemistry beyond that of catalysis. A trinuclear cluster, [(PdPPh3)3(μ-SMe)3]BF4 was isolated as a by-product of these reactions. A series normal and abnormal thiazolylidene complexes of nickel and palladium were prepared by oxidative substitution of the respective 2-, 4- and 5-bromothiazolium salts with M(PPh3)4 (M = Pd or Ni), and unequivocally characterised. In a preliminary catalytic investigation, all the thiazolinium and simple pyridinium derived palladium complexes showed activity in the Suzuki-Miyaura coupling reaction. Little variation in activity in the order a (N next to carbon donor) > n > a (S next to carbon donor) was found for the former series, whereas decreased activity was exhibited in the sequence r > a > n of the latter group. The pyridinium derived complexes showed superior activity to the thiazolinium ones. The rNHC complex, trans-chloro(N-methyl-1,2,4-trihydro-2- dimethylaminepyrid-4-ylidene)bis(triphenylphosphine)palladium(II) triflate, showed similar Suzuki-Miyaura activity to the standard N2HC5 carbene complex precatalyst, trans-chloro[(1,3- dimethyl-imidazol-2-ylidene)triphenylphosphine]palladium(II) triflate.

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48

Julius, Gerrit R. "New transition metal carbene complexes for application in homogeneous catalysis." Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/1391.

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Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch,2005.
This study comprises the preparation and full characterisation of new carbene complexes of group 10 metals (Ni, Pd or Pt), the group 9 metal, rhodium, as well as group 6 metals (Cr and/or W). N-heterocyclic carbene (NHC) complexes of nickel and palladium were prepared via oxidative addition of the corresponding carbene precursors imidazolium-, imidazolinium-, pyridinium- and quinolinium chloride salts, to M(PPh3)4 (M = Ni or Pd). Three types of carbene complexes, namely the standard five-membered two-N carbene complexes, new six-membered NHC complexes and novel six-membered rNHC complexes received attention. In the rNHC complexes the heteroatom (N) is removed from the carbene carbon. These new square planar carbene complexes of the general formula trans-[(PPh3)2MCl(L)]X (M = Ni or Pd; X = BF4 or PF6) L = 1,3-dimethyl-2,3-dihydro-1Himidazol- 2-ylidene, 1,3-dimethyl-2,3,4,5-tetrahydro-1H-imidazol-2-ylidene, 1-methyl-1,2-dihydropyridin- 2-ylidene, 1-methyl-1,2-dihydro-quinolin-2-ylidene, 1,4-dimethyl-1,2-dihydro-quinolin-2- ylidene, 2-methoxy-1-methyl-1,4-dihydro-quinolin-4-ylidene, 1-methyl-1,4-dihydro-pyridin-4- ylidene) have been isolated and characterised. The preparation of the corresponding carbene complexes of platinum was complicated by the formation of [PtCl(PPh3)3]BF4 and the desired carbene complexes could not be isolated in pure form. The investigation of rNHC complexes was extended to include the synthesis of (CO)5M{CSC(CNCMe2CH2O)CHCH} (M = Cr and W). The molecular and crystal structures of thirteen of the new carbene complexes including the structures of both cis- (only formed below –20°C) and trans-chloro(1-methyl-1,2-dihydro-quinolin- 2-ylidene)bis(triphenylphosphine)palladium(II) tetrafluoroborate were determined. The metalcarbene bond distances in both the palladium and nickel carbene families do not differ significantly. The carbene ligands can be arranged in a series of increasing trans-influence, using the metalchloride bond distance as a guideline, as follows: 1,3-dimethyl-2,3-dihydro-1H-imidazol-2-ylidene and 1,3-dimethyl-2,3,4,5-tetrahydro-1H-imidazol-2-ylidene < 1-methyl-1,2-dihydro-pyridin-2- ylidene < 2-methoxy-1-methyl-1,4-dihydro-quinolin-4-ylidene, 1-methyl-1,4-dihydro-pyridin-4- ylidene. The crystal and molecular structures of two platinum compounds, cis-chloro(2-methoxy-1- methyl-1,4-dihydro-quinolin-4-ylidene)bis(triphenylphosphine)platinum(II) tetrafluoroborate and the byproduct [PtCl(PPh3)3]BF4 were also determined. Trans-chloro(2-methoxy-1-methyl-1,4-dihydro-quinolin-4-ylidene)bis(triphenylphosphine) palladium(II) tetrafluoroborate was found to be a very active catalyst, compared to simpler palladium carbene and phosphine complexes, in the Mizoroki-Heck and Suzuki-Miyaura coupling reactions. Quantum mechanical calculations indicated that the rNHC ligand in this complex is bound stronger to the palladium than a standard imidazole-derived NHC ligand. Further calculations suggested that the remote heteroatom carbene (rNHC) complexes of nickel(II) are significantly more stable when compared to the normal carbene (NHC) complexes. Energy decomposition analysis suggested that the rNHC ligands are strong s-donors and weak -acceptors. Unsymmetrical imidazolium-derived bis(carbene) complexes, [Rh(NHC)2COD]Br, bromomono( carbene) complexes, Rh(Br)COD(NHC), and chloro-mono(carbene) complexes, Rh(Cl)COD(NHC) where NHC = 1-R-3-methyl-2,3-dihydro-1H-imidazol-2-ylidene (R = ethyl, propyl or butyl), were formed in each reaction of the corresponding free carbene ligand with [Rh(Cl)COD]2. [Rh(Br)COD(NHC)] formed as a result of substitution of a chloride ligand by a Br-- anion. The carbonyl complexes, cis-[Rh(CO)2X(NHC)] (X = Br or Cl; NHC = 1-ethyl-3-methyl- 2,3-dihydro-1H-imidazol-2-ylidene) were isolated after the substitution of the COD ligand in Rh(X)COD(NHC) (X = Br or Cl) with CO. Isomerisation of these cis-carbonyl complexes to the trans isomers was observed. Cis-[(h4-1,5-cyclooctadiene)bis(1-butyl-3-methyl-2,3-dihydro-1H-imidazol-2-ylidene)rhodium(I)] bromide, bromo(h4-1,5-cyclooctadiene)(1-methyl-3-propyl-2,3-dihydro-1H-imidazol-2-ylidene) rhodium(I) and cis-[(h4-1,5-cyclooctadiene)bis(1-butyl-3-methyl-2,3-dihydro-1H-imidazol-2- ylidene)rhodium(I)]bromide were also characterised by single crystal X-ray diffraction. The synthesis and structural characterisation of a series of acyclic and heterometallacyclic Fischertype carbene complexes in which a soft donor atom (P) attached to the carbene side chain is either uncoordinated, (CO)5M=C(NMe2)CH2PPh2 (M = Cr or W), bonded to the original central metals (Cr or W) in four-membered chelates, (CO)4M=C(NMe2)CH2PPh2, or coordinated to a second M(CO)5 unit (only isolated for chromium) (CO)5Cr=C(NMe2)CH2P(Ph2)Cr(CO)5, were carried out. These compounds were produced by the reaction of the anionic Fischer-type aminocarbene complexes, [(CO)5Cr=C(NMe2)CH2]Li (M = Cr or W), with ClPPh2. The formation of the four-membered chelates, via cyclisation, occurs much faster for Cr than for W. The aminocarbene-phosphine chelates represent the first examples of structurally characterised, four-membered C,P-chelate carbene complexes.

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49

Kuchenbeiser, Glenn Richard. "Reactivity of bis(amino)cyclopropenylidenes (BACs) and cyclic (alkyl)(amino)carbenes (CAACs) coordination chemistry, catalysis, and small molecule activation /." Diss., [Riverside, Calif.] : University of California, Riverside, 2009. http://proquest.umi.com/pqdweb?index=0&did=1899480521&SrchMode=2&sid=4&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1269286714&clientId=48051.

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Thesis (Ph. D.)--University of California, Riverside, 2009.
Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 10, 2010). Includes bibliographical references. Also issued in print.

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50

Santoro, Orlando. "Copper(I)-N-heterocyclic carbene (NHC) complexes : synthesis, characterisation and applications in synthesis and catalysis." Thesis, University of St Andrews, 2016. http://hdl.handle.net/10023/8409.

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The work described herein focuses on the synthesis and characterisation of copper(I) complexes bearing N-heterocyclic carbene (NHC) ligands, their use in catalysis as well as organometallic synthesis and related reaction mechanisms. Two classes of complexes were considered: neutral NHC-Cu(I) species and their cationic analogues. Concerning the former, initial efforts were focused on the development of a general and straightforward synthetic methodology towards complexes of the type [Cu(X)(NHC)] (X = Cl, Br, I). More than 10 NHC-Cu(I) species were synthesised in high yields under mild conditions, in air and using technical grade solvents. These complexes exhibited interesting activity in the catalytic dehydrogenation of formic acid/amine adducts proving in three times more efficiency than the copper salts previously employed in such a reaction. Hydroxide- and tert-butoxide analogues showed to be efficient catalysts in the N-methylation of amines with CO₂ as carbon source, and in the dehydrogenative coupling of silanes and carboxylic acids. Experimental and computational work were carried out in order to elucidate the mechanism of these transformations. Regarding the use of these species in organometallic synthesis, homo- and heteroleptic bis-NHC-Cu(I) complexes were employed as carbene transfer reagents to other transition metals. Aside from well-known cationic gold(I) species, two novel palladium(II) analogues were isolated and fully characterised.

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Dissertations / Theses on the topic 'Carbenes (Methylene compounds)'

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