Rozprawy doktorskie na temat „Metal thiolates”

Ce projet concerne la synthèse et caractérisation de nouveaux matériaux composites à base de nanoclusteurs de thiolates d’or Au25(SR)18 (tGNCs), supportés sur divers polymères de coordination (MOFs), ainsi que sur ZrO2. L’activité catalytique de ces matériaux a été évaluée sur la transformation de différents substrats. Les tGNCs sont des matériaux atomiquement bien définis et connus pour être actifs dans des réactions d’oxydation. Les nanoparticules de MOFs sont des matériaux pouvant servir de support pour des tGNCs avec de bonnes dispersions. Certains MOFs sont connus pour avoir des propriétés acides et peuvent être actifs en catalyse. Parmi eux, MIL-101 (Cr), UiO-66 (Zr) et ZIF-8 (Zn) on été choisis en raison de leur propriétés acides et/ou de stabilité thermique. La synergie entre les tGNCs et les MOFs a été évaluée à travers la conversion catalytique de différents substrats tels le glucose, le fructose, l’alcool benzylique et le furfural, impliquant des étapes nécessitant un caractère acide et/ou oxydant. Globalement, il n’a pas été observé d’impact de la présence d’or sur la réactivité de ces substrats, et les tendences catalytiques sont celles obtenues avec les MOFs seuls. Cela est certainement dû à la stabilité thermique non suffisante des MOFs qui prévient une calcination efficace des tNGCs. Lorsque ces clusters sont déposés sur ZrO2, il a été possible de les calciner à différentes températures pour étudier l’effet du ligand et de la taille de particules, pour des réactions d’oxydation en phase liquide. Ainsi, il a été montré par exemple que la température de calcination a un impact significatif sur le comportement catalytique de ces composites, qui ont donné de bonnes activités pour l’oxydation de l’alcool benzylique en benzaldéhyde dans le toluène et en conditions douces, et pour l’esterification oxydante du furfural en furoate de méthyle
This research project reports the synthesis and characterization of new composite materials based on Au25(SR)18 thiolate gold nanoclusters (tGNCs), supported over a range of metal organic frameworks (MOFs), and ZrO2. The synthesized composite materials were tested for catalytic transformations of various substrates. tGNCs are atomically well defined materials known to be active in oxidation reactions. MOFs nanoparticles are materials suitable for high dispersion of tGNCs. Some MOFs are known to have acidity and can be active as catalysts. Among them, MIL-101 (Cr), UiO-66 (Zr) and ZIF-8 (Zn) were chosen due to their acidic and/or thermal stability properties. The synergy between tGNCs and MOFs has been tested through catalytic conversions of different substrates like glucose, fructose, benzylalcohol and furfural, involving steps requiring acidic and oxidative features. Globally, no impact of the presence of Au clusters was observed, and the composite materials showed the same catalytic trends as those obtained with the MOFs alone. This is mainly due to the not sufficient thermal stability of the MOFs that prevents efficient calcination of the tGNCs. In contrast, when deposited on ZrO2 it was possible to calcine Au25(SG)18 nanoclusters at different temperatures to study the ligand and particle size effects in liquid phase oxidation reactions. For example, the calcination temperature had a significant impact on the catalytic behaviour of this composite materials, which showed good activity for the oxidation of benzyl alcohol into benzaldehyde in toluene under mild conditions, and of furfural oxidative esterification into methyl-2-furoate

The research outlined in this dissertation focuses on understanding the role of metal-sulfur interactions as applied to bioinorganic and organometallic systems. This metal-sulfur interaction is analyzed using both gas-phase photoelectron spectroscopy (PES) and density functional theory (DFT). Gas-phase photoelectron spectroscopy is the most direct probe of electronic structure and is used in these studies to probe the molecular orbital energy levels of these model compounds, giving rise to an understanding of the metal and sulfur orbital interactions and characters (i.e. is an orbital primarily metal or sulfur based). Using density functional theory, orbital energies, overlap, and characters can be calculated and complement the PES experiments allowing for a detailed understanding of the electronic structure. The first part of my dissertation explains the design and implementation of a dual source gas-phase ultraviolet/X-ray photoelectron spectrometer (UPS/XPS). This gas-phase UPS/XPS can be used to quantify the bonding/antibonding character of frontier molecular orbitals, with specific applications to metal-sulfur interactions, allowing for a thorough analysis of the metal-sulfur interaction. The second part of the dissertation explores using model complexes, of the type Cp₂V(dithiolate) (where Cp is cyclopentadienyl and dithiolate is 1,2-ethenedithiolate or 1,2-benzenedithiolate), along with PES and DFT calculations to investigate the role of the pyranopterindithiolate cofactor and the d¹ electron configuration in modulating the redox potential and electron transfer in the active sites of molybdenum enzymes. This study shows that the d¹ electronic configuration offers a low energy electron transfer pathway for the reoxidation of the active site molybdenum center. The third part of the dissertation explores the use of model compounds that specifically focus on iron-thiolate interactions in biological systems, and the effect of electronic energy matching and sterics on the oxidation potential of this interaction. This study has shown that the metal-sulfur interaction is sensitive to the orientation of the thiolate ligand, and that during oxidation an “electronic-buffering effect” makes assigning a formal oxidation state to the metal center almost meaningless. All of these studies illustrate how the thiolate ligand can modulate the electron density and oxidation potential of the metal-sulfur interaction and the implication of this interaction to biological electron transfer.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2008.
Vita.
Includes bibliographical references.
Nitric oxide (NO) is a molecule that is essential for life and regulates both beneficial and harmful processes. Because this gaseous radical influences many aspects of health and disease, we wish to explore the relationship between NO and physiology/pathophysiology. To this end, we seek to create tools for the fluorescent imaging of NO in vivo. We have adapted an existing small molecule-based sensor for more biologically relevant applications by including it within a polymeric film. We have also developed turn-on fluorescent sensors for NO based on conjugated polymers, which demonstrated good selectivity and sensitivity for this analyte. In addition, we have prepared a related sensor that will detect nitroxyl (HNO) but not NO. These systems demonstrate the versatility and value of the conjugated polymer scaffold for sensing applications. Many targets of the diatomic radical NO contain redox active units, such as transition metals or thiolate ligands. To gain insight into how NO might regulate biological processes by interacting with these redox active species, we have initiated a fundamental study of the reactivity of NO with transition metal thiolate model complexes. Our explorations in this field have yielded unique nickel and cobalt nitrosyl species with atypical electronic and structural parameters. These studies have suggested intermediates for the more biologically relevant iron nitrosyl complexes that have not yet been observed may exist. Furthermore, the NO chemistry of these small molecule nickel and cobalt thiolate complexes may guide future biological investigations into the regulation of nickel and cobalt metalloproteins by NO.
Andrew Gregory Tennyson.
Ph.D.

This work has dealt with the synthesis and characterization of transition metal complexes with two types of sulphur based ligands: 1,2 dithiolato ligands and thiol-carboxylate ligands. The electronic features related to the metal-sulphur interaction, such as the rich redox behaviour associated to the interplay between the sulphur and a redox active metal, the better overlap between sulphur and metal orbitals, the ability of forming coordination compounds in different topologies, from discrete complexes to extended 1-D network, make sulphur-based coordination compounds. We have explored these features starting from non redox innocent metal bis-dithiolene complexes as possible molecular precursors in the field of molecular magnetism, as paramagnetic centers able to organize in more complex coordination compounds. In the first part of this work, “classical” metal bis-dithiolene complexes have been investigated as metallo-ligands towards the coordination of “acceptor” metal complexes, in order to build up coordination compounds of higher nuclearities with paramagnetic centers. Particularly, the investigated dithiolenes were [Cu(mnt)2]2- ,[Cu(tfadt)2]2-and [Ni(dmid)2].- while the “acceptor” metal complexes are Mn(III) porphinato ,Mn(III) salen-like complexes and finally a mixed valence Mn(II)Mn(III) complex. We have observed that the reactivity in solution of metal-bis –dithiolene together with the Mn-based complexes employed has lead to co-crystallization salts where the coordinating group of the dithiolene does not coordinate the Mn center. From these observation, we have decided to synthesize a series of new 1,2 dithiolato ligands bearing a potential coordinating functional group. We have choosen to functionalize them with crown-ether macrocycles with different sizes, in order modulate their selectivity for transition metal ions or lanthanide ions. The corresponding radical nickel(dithiolene) complexes have been synthesized and polymetallic Ni-Na and Ni-Ni chains have been obtained as well as a bimetallic Ni-Ni discrete complex. We have provided their physico-chemical characterizations in order to understand their rich redox behaviour and their magnetic properties. The investigation on these new 1,2 dithiolato ligands is still in progress in order to build up polymetallic assemblies also with lanthanide ions. We have then switched to another class of sulphur-based ligands, the thiol-carboxylate ligands. 2-mercaptonicotinic acid has been considered as versatile ligand towards the synthesis of sulphur-based metal complexes. This polyfunctional ligand can coordinate with N, O or S donor atoms. Under hydrothermal conditions, Zn(II) and 2-mercaptonicotinic acid afforded a coordination polymer where 2-mercaptonicotinic acid is S,O chelating. The electronic properties were studied by means of theoretical calculations and experimental measurments. Under the same reaction conditions, Ni(II) did not led to any crystalline material. By switching the reaction conditions, it has been observed a mononuclear S,O chelated Ni bis(mercaptonicotinate).
Questo lavoro di dottorato ha riguardato la sintesi e la caratterizzazione di complessi di metalli di transizione con leganti donatori allo zolfo. In particolare sono stati considerati i leganti 1,2 ditiolato e un legante tipo tiol-carbossilato, l’acido 2-mercaptonicotinico. Lo zolfo presenta una variabilità maggiore di stati di ossidazione rispetto all’ossigeno e a questo si riconduce il particolare comportamento redox dei complessi con legami M-S. Per questo motivo la sintesi di complessi implicanti il legame metallo-zolfo è un’area di ricerca attiva soprattutto per quanto riguarda la progettazione di materiali con proprietà di conduzione, ottiche o magnetiche. In questo contesto sono stati considerati i complessi dei metalli di transizione con i leganti 1,2 ditiolato, altresi detti metallo bis-ditioleni. Nei metallo bis-ditioleni la variabilità degli stati di ossidazione del complesso senza grandi variazioni della geometria di coordinazione li rende adatti per la sintesi di materiali molecolari. In particolare, una via sintetica per l’ottenimento di tali materiali consiste nell’organizzare questi complessi via coordinazione ad un altro centro metallico, in maniera da ottenere composti a più alta nuclearità. Soprattutto per quanto riguarda il magnetismo molecolare, vi è la necessita di organizzare nella stessa molecola più centri paramagnetici. In questo lavoro di tesi, inizialmente dithioleni paramagnetici “classici” come [Cu(mnt)2]2- ,[Cu(tfadt)2]2-and [Ni(dmid)2].-, contenenti gruppi funzionali potenzialmente coordinanti sono stati impiegati come metallo-leganti verso complessi paramagnetici di Mn(III) o a valenza mista Mn(II)/Mn(III). Durante gli esperimenti condotti, è risaltata la reattività in soluzione dei metallo bis-ditioleni verso lo scambio di leganti che non ha condotto alla formazione del complesso polunucleare sperato, sebbene siano stati isolati composti potenzialmente interessanti. Alla luce di tutto cio, è stata intrapresa la sintesi di nuovi leganti 1,2 ditiolato opportunamente funzionalizzati con gruppi coordinanti quali gli eteri corona. La versatilità dei ditioleni verso la funzionalizzazione ha permesso di realizzare una serie di leganti con diverse dimensioni del macrociclo, in modo da poter modulare la selettività verso metalli di transizione ma anche verso ioni di lantanidi trivalenti. Sono stati sintetizzati a partire da questi leganti i complessi ditioleni di nickel, isolandoli in forma di anioni e aventi spin S=1/2. Sono state ottenuti complessi polimetallici Ni-Ni e Ni-Na. Inoltre è stato ottenuto un complesso bimetallico Ni-Ni. Tutti i complessi sono stati caratterizzati chimicamente. Inoltre, le proprietà magnetiche sono state indagate tramite misure di suscettività magnetica in funzione della temperatura, rivelando per il complesso polimetallico Ni-Ni una forte interazione fra le unità ditiolene costituenti il complesso. Il legante tiol-carbossilato acido 2- mercaptonicotinico è stato considerato per la sua versatilità alla coordinazione. In condizioni idrotermali e in presenza di Zn(II) e acido 2-mercaptonicotinico, è stato ottenuto un polimero di coordinazione dove il legante mercaptonicotinato funge da chelante S,O e lega a ponte monoatomico i vicini centri metallici. La stessa topologia non è stata ottenuta con il Ni(II). Cambiando le condizioni di reazione, finora solo il complesso monometallico Ni(II) bis-mercaptonicotinato è stato ottenuto. Le proprietà elettroniche correlate alla situazione di coordinazione S-Zn-O del polimero di coordinazione di Zn(II) sono state investigate per mezzo di calcoli teorici e misure sperimentali.

Les polymères de coordination (PCs) à base de thiolates de métaux monétaires sont bien connus pour leurs propriétés luminescentes. Cependant, leurs structures sont sous-explorées. Dans cette thèse, nous présentons une étude pionnière visant la compréhension de la formation de la structure et de la corrélation ‘structure-propriétés’ des PCs homoleptiques neutres, [M(SR)]n, M = Cu(I), Ag(I), Au(I). Les composés avec les dérivés du thiophénolate étudiés dans ce travail, illustrent comment l'utilisation de certains ligands organiques fonctionnalisés conduit à la formation de réseaux 2D étendus ou de colonnes 1D par l'addition d'un encombrement stérique. De plus, la première étude structurelle comparative des PCs thiolées amorphes a été réalisée par analyse PDF. Les études photophysiques ont montré la diversité des propriétés luminescentes des PCs à base de thiolates de métaux monétaires. Des pics d'émission doubles ou multiples, un rendement quantique élevé, des émetteurs orange à proche infrarouge, des variations significatives de durée de vie en fonction de la température... toutes ces propriétés intrinsèques révèlent le potentiel élevé de ces composés pour diverses applications optiques
The coordination polymers (CPs) based on thiolates of coinage metals are well known for their luminescence properties. However, their structures stayed underexplored. In the thesis we present a pioneering study targeting the understanding of the structure formation and the ‘structure-properties’ correlation for neutral homoleptic CPs, [M(SR)]n, M = Cu(I), Ag(I), Au(I). The compounds with thiophenolate derivatives studied in the work, illustrate how the use of some functionalized organic ligands leads to the formation of extended 2D networks or 1D columns by addition of some steric hindrance. The first comparative structural study of amorphous thiolated CPs was performed by PDF analysis. The photophysical studies showed the diversity of luminescent properties of the CPs based on thiolates of coinage metals. Double or multiple emission peaks, high quantum yield of orange-toinfrared emitters, significant lifetime variation with temperature… all of these intrinsic properties reveal the high potential of these compounds for diverse optical applications

Cette thèse présente la synthèse et la caractérisation de complexes moléculaires bio-inspirés àliaison métal-thiol avec l'objectif de modéliser le site actif de certaines métalloenzymes. Enparticulier, notre but était d'améliorer notre compréhension sur le rôle que joue cette liaisonmétal-thiol dans les métalloenzymes, notamment au niveau de ses propriétés structurales etélectroniques ainsi que sur la réactivité des sites actifs associés. Le thiol lié à un métal peut êtresujet à deux types de réaction dans métalloenzymes : les réaction de S- alkylation ou de Soxygénation.Il a été montré que la réactivité de ces ligands thiols dépend fortement de la naturede l'ion métallique. Dans ce contexte, différents complexes thiolate Mn+ ont été synthétisés (VIII,VIV, VV, NiII, NiIII, CoII et CoIII), soit avec un ligand LN2S2 tétradentate ou LNS2 tridentate. Ces deuxligands sont constitués d'un ou deux azote(s) aromatique(s) (bipyridine ou pyridine) et de deuxthiols aliphatiques encombrants.Nous avons montré que le CoII ion représente un substitut structural satisfaisant pour lesmétalloenzymes contenant du zinc. Cependant, il n'est pas approprié comme substitutfonctionnel dans le cas particulier de la réaction de S- alkylation. En outre, nous avons pumodéliser l'étape d'activation de nitrile hydratase à cobalt, avec l'incorporation de trois atomesd'oxygène sur un complexe bis-thiolate de CoIII présentant la même dissymétrie que dansl’enzyme lors de la réaction de S- oxygénation. En revanche, avec le vanadium et le nickel, desespèces métal-peroxo ont pu être générées sans réaction intramoléculaire de S- oxygénation.Nos travaux ont ainsi conduit à l’obtention des premiers exemples de complexes peroxos dunickel et du vanadium possédant des liaisons métal-thiol.Nous avons également tenté de modéliser des réactions réalisées par des métalloenzymes dontle site actif est riche en soufre, dont l'activation et la réduction du diazote en ammoniac, réactionréalisée par les nitrogénases. Pour modéliser ces enzymes, un complexe thiolate du VIII a étésynthétisé et sa réactivité étudiée. Nos résultats préliminaires suggèrent que l’espèce réduite deVII correspondante est capable d'activer et de réduire l’hydrazine en ammoniac, réactioncorrespondant à la dernière étape de la réduction du diazote
This thesis presents the synthesis and characterisation of bio-inspired molecular complexescontaining metal alkyl thiolate bonds with the goal of modelling metalloenzymes. In particular,we have attempted to improve our knowledge on the role that the bound alkyl thiolate plays inmetalloenzymes, including, structural features, electronic properties and also reactivity of theassociated active sites. The bound alkyl thiolate undergoes two main reactions inmetalloenzymes; S-alkylation and S-oxygenation. From the isolation and characterisation of thecorresponding active sites, it can be seen that the reactivity of the bound alkyl thiolate dependsgreatly on the metallic ion. In this context, different Mn+-thiolate complexes have beensynthesized (VIII, VIV, VV, NiII, NiIII, CoII and CoIII), with either a tetradentate LN2S2 or a tridentateLNS2 ligand. Both ligands consist of aromatic nitrogen (bipyridine or pyridine) donor atom(s)and also two bulky S-thiolate donor atoms.We have shown that the CoII ion is a suitable structural substitute for Zn-containingmetalloenzymes, however, it is inappropriate as a functional substitute in the particular case ofS-alkylation. Furthermore, we have been able to structurally model the activation step of cobaltnitrile hydratase, with the incorporation of three oxygen atoms on a CoIII bis alkyl thiolatecomplex evidencing dissymmetrical S-oxygenation. In contrast, using vanadium and nickel,metal-peroxo species have been generated, without intramolecular S-oxygenation. This researchhas led to some of the first examples of active oxygen nickel and vanadium complexes usingalkyl thiolate ligands.We have also attempted to model very difficult reactions carried out by sulfur richmetalloenzymes, especially the activation and reduction of dinitrogen realised by nitrogenases.To model this enzyme, a VIII alkyl thiolate complex has been synthesised and its reactivityinvestigated. Preliminary results suggest that the reduced VII species has the ability to activateand reduce hydrazine into ammonia, which is proposed to be the final stage of dinitrogenreduction

Caracterisation des complexes ((c::(5)h::(5))(co)::(2) lwc(cf::(3)) = c(cf::(3))h) et (c::(5)h::(5))(co) lwc(o)c(cf::(3)) = c(cf::(3))h) (l=co,pr::(3),p(or)::(3)) synthese de complexes dinucleaires de mo et w. L'addition oxydante de dialkylsulfure a des derives biportes de mo(ii) et w(ii) a donne lieu a la formation de complexes thiolato triportes ((c::(5)h::(5))(co)m(mu -sr)::(3)m(co)(c::(5)h::(5)))tx**(-)

Cinq familles de composes isotypes ont ete identifiees en milieu aqueux. Etude radiocristallographique, comportement thermique dans differentes atmospheres, preparation du squarate de cerium anhydre et de trois nouvelles phases hydratees. Etude spectrometrique du derive de l'europium

Etude de la reactivite de complexes thiolates du fer et du tungstene (cp(co)::(n) m(sch::(3))) vis a vis du mono et du dicyanoacetylene. Aptitude des complexes de co(i) a intervenir dans la formation de molecules organiques. Nature des liaisons m-pb(m=mo ou w) dans les complexes cp(co)::(3)m-pbr::(3) et (cp(co)::(3)m)::(2) pbr::(2). Donnes de rmn de **(95)mo et **(207)pb

碩士
國立中正大學
化學研究所
91
The research focus in this thesis is classified into three parts. The first part includes the synthesis of pyridyl-amide ligands by one-pot reaction with high yields. Second part is to utilize a series of the designed pyridyl amides (L1-L6) as bridging ligands for the construction of molecular squares with Re(I) or Mn(I) ions as corners. The hydrogen-bonding functions of pyridyl amides may be anticipated to contribute in the formation of supramolecular nanotubes as functional materials by self assembly. The spectroscopic and photophysical properties were also investigated. The lower energy of 3d orbital for Mn(I) ion than 5d orbital for Re(I) as well as low-energy -* orbitals of pyridyl amides led to the red shift of charge-transfer band for Re(I)-based squares compared to Mn(I)-based squares and also a low-energy emission for the Re(I) ones. The porous nature or luminescence properties of the compounds studied here maybe make them potential candidates in chemical sensing. Third part is to synthesize the luminescent Au(I) compounds with 2-amino- 5-mercapto-1,3,4-thiadiazolate (SSNH2) and 6-amino-2-mercapto- benzothiazolate (SSCNH2) ligands and to study the structural chemistry. From the X-ray structural data, [Au(SSNH2)P(CH2CH2CN)] forms one-dimensional hydrogen-bonded framework, but [Au(SSCNH2) P(CH2CH2CN)] forms a two-dimensional framework owing to the additional involvement of the CN moiety in hydrogen bonding. The solid-state luminescence is also studied.

Small molecule Zn(II) complexes containing N- and S- donor environments may serve as appropriate models for mimicking Zn protein sites, and thus, their reactions with heavy metal ions such as Pt(II) and W(0) may provide insight into possible adduct formation and zinc displacement. To study such possible interactions between zinc finger proteins and platinum-bound DNA, the ZnN2S2 dimeric complex, N,N?-bis(2- mercaptoethyl)-1,4-diazacycloheptane zinc (II), [Zn-1?]2, has been examined for Znbound thiolate reactivity in the presence of Pt(II) nitrogen ? rich compounds. The reactions yielded Zn/Pt di- and tri- nuclear thiolate-bridged adducts and metalexchanged products, which were initially observed via ESI-mass spectrometry (ESI-MS) analysis of reaction solutions, and ultimately verified by comparison to the ESI-MS analysis, 195Pt NMR spectroscopy, and X-ray crystallography of directly synthesized complexes. The isolation of Zn-(?-SR)-Pt-bridged [(Zn(bme-dach)Cl)(Pt(dien))]Cl adduct from these studies is, to our knowledge, the first Zn-Pt bimetallic thiolatebridged model demonstrating the interaction between Zn-bound thiolates and Pt(II). Additional derivatives involving Pd(II) and Au(III) have been explored to parallel the experiments executed with Pt(II). The [Zn-1?]2 was then modified by cleavage with Na+[ICH2CO2]- to produce (N- (3-Thiabutyl)-N?-(3-thiapentaneoate)-1,4-diazacycloheptane) zinc(II), Zn-1?-Ac or ZnN2SS?O, and 1,4-diazacycloheptane-1,4-diylbis(3-thiapentanoato) zinc(II), Zn-1?-Ac2 or ZnN2S?2O2, monomeric complexes (where S = thiolate, S? = thioether). The [Zn-1?]2 di- and Zn-1?-Ac mono-thiolato complexes demonstrated reactivity towards labile-ligand tungsten carbonyl species, (THF)W(CO)5 and (pip)2W(CO)4, to yield, respectively, the [(Zn-1?-Cl)W(CO)4]- complex and the [(Zn-1?-Ac)W(CO)5]x coordination polymer. With the aid of CO ligands for IR spectral monitoring, the products were isolated and characterized spectroscopically, as well as by X-ray diffraction and elemental analysis. To examine the potential for zinc complexes (or zinc-templated ligands) to possibly serve as a toxic metal remediation agents, Zn-1?-Ac and Zn-1?-Ac2 were reacted with Ni(BF4)2. The formation of Zn/Ni exchanged products confirmed the capability of ?free? Ni(II) to displace Zn(II) within the N-, S-, and O- chelate environment. The Zn/Ni exchanged complexes were analyzed by ESI-MS, UV-visible spectroscopy, IR spectroscopy of the acetate regions, and X-ray crystallography. They serve as foundation molecules for more noxious metal exchange / zinc displacement products.

Thesis (Ph. D.)--University of Illinois at Urbana-Champaign, 2008.
Source: Dissertation Abstracts International, Volume: 69-11, Section: B, page: 6795. Adviser: Yi Lu. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.

碩士
國立成功大學
化學系碩博士班
100
At this work, several vanadium-thiolate complexes have been obtained and characterized. They are [VIII(PS2”SH)2][PPh4] (1), [VIV(PS3”)(PS2”SH)][PPh4] (2) and [V(PS3”)2][NEt4] (3). (PS2”SH = [P(C6H3-3-Me3Si-2-S)2 (C6H3-3-Me3Si-2-SH)]2-. PS3” = [P(C6H3-3-Me3Si-2-S)3]3-). The reactivity of them with air/dioxygen, CH2Cl2 and CHCl3 have also been explored. The evidence were supported by several physical methods, including X-ray crystallography, UV-vis, NMR spectroscopies, and ESI-MS studies. Complexes 1, 2 and 3 exhibited several types of reactivity toward dioxygen. They include metal-center oxidation, thiyl-radical formation, and oxygenation on metal bound thiolate. The hexa-coordinated [VIII(PS2”SH)2][PPh4] (1) reacted with dioxygen to a hepta-coordinated [VIV(PS3”)(PS2”SH)][PPh4] (2). Complex 2 was further oxidized to yield an octa-coordinated [V(PS3”)2][NEt4] (3), a species with charge delocalization character between vanadium and sulfur centers. During the oxidation process, the corresponding vanadium sulfenate/sulfinate species of 2 and 3 were also observed. Complex 3, a species with resonance forms between V(V)-thiolate and V(IV)-thiyl radical, also reacted with H2O and form 2 by homolytic cleavage of the O-H bond in water. In addition, complex 3 also reacted with CH3OH via homolytic cleavage of the O-H bond and C-O bond in methanol. Consequently, it led to the formation of complex 2 and [VIV(PS3”)(PS2”SCH3)]- (4a), a bound thiolate was protonated and methylated to form an unbound thiol (in 2) and methylether (in 4a), respectively. Finally, 3 can undergo C-Cl bond activation toward CH2Cl2 to form [VIII(PS3”)Cl][PPh4] (5) and [VIV((PS3”)2CH2)] (6), a VIII-Cl species and a VIV species containing two PS3” with CH2 linkage between two thiolates. The similar reactivity toward CHCl3 was also observed. Complexes 1 and 2 can undergo C-Cl bond activation toward CH2Cl2 to produce 5 and 6. In contrast to the reactivity of 3 with CH2Cl2, a homolytic cleavage of C-Cl bond through a radical mechanism, the reactivity of 1 and 2 with CH2Cl2 might undergo through nucleophilic attack of the lone paired electrons on bound sulfur. The reaction with CHCl3 also showed similar reactivity as CH2Cl2.