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Dissertations / Theses on the topic 'Tungsten carbonyl complexes'

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Published: 4 June 2021

Last updated: 1 February 2022

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1

Wang, I.-Hsiung 1950. "Kinetics Studies of Substituted Tungsten Carbonyl Complexes." Thesis, University of North Texas, 1989. https://digital.library.unt.edu/ark:/67531/metadc330797/.

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Thermal reactions and flash photolysis are used to study the olefin bond-migration promoted by tungsten carbonyls. Substitution of piperidine (pip) by 2- allylphenyldiphenylphosphine (adpp) in the cis-(pip)(η^1- adpp)W(CO)-4 complex was investigated, and no olefin bond-migration was observed. This suggests that a vacant coordinated site adjacent to the coordinated olefin is an essential requirement for olefin bond rearrangement. The rates of olefin attack on the photogenerated coordinatively unsaturated species, cis-[(CB)(η^1-ol- P)W(CO)-4] (CB = chlorobenzene, p-ol = Ph-2P(CH-2)-3CH=CH-2; n = 1-4) were measured. Kinetics data obtained both in pure CB and in CB/cyclohexane mixtures support a dissociative mechanism in which the W-CB bond is broken in the transition state. In contrast to results observed in studies of other related systems, no olefin bond-migration is noted. This observation is attributed to P-W coordination at all stages of the reaction, which precludes formation of a reactive intermediate containing a vacant coordination site adjacent to a P-ol bond.

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2

Walker, Daniel James. "Fluorinations of tungsten and molybdenum carbonyl complexes." Thesis, University of Leicester, 1997. http://hdl.handle.net/2381/30011.

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The dimeric complexes (n5-C5H5)M(CO)3 2 (where M = W or Mo) and (H3C{ti5-C5H4})Mo(CO)3 2 have been treated with XeF2 in organic solvents. All three materials react to form air sensitive products which solid-phase IR studies show to contain highly oxidised metal carbonyl components. The product from the fluoridation of (H3C{T 5-C5H5})Mo(CO)3 2 is insufficiently stable in solution for it to be characterised further. 19F NMR studies show that (n5-C5H5)W(CO)3 2 reacts to form the new complex (T 5-C5H5)WF5, but that the molybdenum analogue reacts to form an unidentified product which, although it produces an AB4 pattern in the 19F NMR, does not appear structurally related to (n5-C5H5)WFs. (n5-C5H5)W(CO)3 2 was found to react with AgF in anhydrous HF solution to give (t 5-C5H5)WF5. Solid-phase IR studies showed that a highly oxidised metal carbonyl, identical to that obtained in the XeF2 reaction, was also formed. Reaction of (T 5-C5H5)M(CO)3(CH3) (where M = W or Mo) with anhydrous HF was found to yield the complexes (n5-C5H5)M(CO)3 2 (where M = W or Mo). The molybdenum product was characterised by X-ray crystallography, whilst the tungsten dimer was characterised using mass spectroscopy. The mechanism for this redox process is unknown, but is believed to involve formation of the complexes (T 5-C5H5)M(CO)3F, as intermediates. Although solid-phase IR shows that both Mo(CO)6 and W(CO)6 react with XeF2 to give oxidised metal carbonyls, the products appear very different. W(CO)6 yields a variety of salts of the W202F9 " anion, none of which dissociate fully in solution, and which thus give separate 19F NMR spectra, for the anion. One of these salts may contain the W2(CO)8 2+ cation, which has been characterised in the product mixture by +EI MS. Mo(CO)6 reacts to form a molybdenum fluoride whose 19F NMR spectrum has been observed, but which has not been identified.

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3

Reinisch, Paul Frederick. "The chemistry of dinuclear complexes of tungsten containing phosphido ligands." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304513.

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4

Kavakli, Cuneyt. "Synthesis And Characterization Of Carbonyl - Tungsten(0) Complexes Of [n,n&#039." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606101/index.pdf.

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In this study a bidentate ligand containing two ferrocenyl moieties, N,N&#039<br>-bis(ferrocenylmethylene)ethylenediamine, was prepared by condensation reaction of ferrocenecarboxyaldehyde and ethylenediamine on refluxing in benzene. The molecule was identified by IR, Raman, UV-VIS, 1H-, 13C-NMR spectroscopies. Then, this bidentate ligand was reacted with pentacarbonylbis-(trimethyl)silylethyne)tungsten(0). The ligand substitution reaction in dichloromethane yielded the new complex, tetracarbonyl [N,N&#039<br>-bis(ferrocenylmethylene)ethylenediamine]tungsten(0) (W(CO)4(BFEDA)). This new complex was isolated from the reaction solution in the form of orange crystals and fully characterized by elemental analysis, IR, UV-VIS, MS, 1H- and 13C-NMR spectroscopies. As a bidentate ligand, [N,N&#039<br>-bis(ferrocenylmethylene)ethylenediamine] binds the metal atom in the two cis positions in the pseudooctahedral geometry of the tungsten-complex. Electrochemistry of the tetracarbonyl [N,N&#039<br>-bis(ferrocenylmethylene)ethylenediamine]tungsten(0) was studied by cyclic voltammetry, and controlled potential electrolysis combined with the UV-VIS spectroscopy. One irreversible oxidation and three reversible oxidations were observed in the cyclic voltammogram. One of these reversible and the irreversible oxidations are attributed to tungsten and the other two reversible oxidations to iron centers. It is found that the two ferrocene groups started communication with each other after formation of tungsten-complex. N,N&#039<br>-bis(ferrocenylmethylene)ethylenediamine was also reacted with photogenerated pentacarbonyl(tetrahydrofuran)tungsten(0) complex and the pentacarbonyl [N,N&#039<br>-bis(ferrocenylmethylene)ethylenediamine]tungsten(0) (W(CO)5(BFEDA)) as an intermediate on the route to the tetracarbonyl[N,N&#039<br>-bis(ferrocenylmethylene)ethylenediamine]tungsten(0) was isolated from the reaction medium in the form of red crystals and fully characterized by, IR, 1H- and 13C-NMR spectroscopies. The conversion of W(CO)5(BFEDA) to the W(CO)4(BFEDA) in dichloromethane by a ring closure mechanism was observed by IR spectroscopy.

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5

Zhang, Shulin. "Studies of Solvent Displacement from Solvated Metal Carbonyl Complexes of Chromium, Molybdenum, and Tungsten." Thesis, University of North Texas, 1990. https://digital.library.unt.edu/ark:/67531/metadc331992/.

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Flash photolysis techniques were applied to studies of solvent displacement by Lewis bases (L) from solvated metal carbonyl complexes of Cr, Mo, and W. On the basis of extensive studies of the reaction rate laws, activation parameters , and linear-free-energy-relationships, it was concluded that the mechanisms of solvent displacement reactions depend on the electronic and steric properties of the solvents and L, as well as the identities of the metal atoms. The strengths of solvent-metal bonding interactions, varying from ca. 7 to 16 kcal/mol, and the bonding "modes" of solvents to metals are sensitive to the structures of the solvent molecules and the identities of the metal centers. The results indicate dissociative desolvation pathways for many arene solvents in (solvent)Cr(CO)_5 (solvent = benzene, fluorobenzene, toluene, etc.) complexes, and are consistent with competitive interchange and dissociative pathways for (n-heptane)M(CO)_5. Different types of (arene)-Cr(CO)_5 interactions were suggested for chlorobenzene (CB) vs. fluorobenzene and other non-halogenated arenes, i.e. via σ-halogen-Cr bond formation in the CB solvate vs. π-arene-Cr bond formation through "isolated" double bonds in solvates of the other arenes. The data also indicate the increasing importance of interchange pathways for solvent displacement from the solvates of Mo and W vs. that of Cr.

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6

Hirsivaara, L. (Leeni). "Coordination chemistry of arylphosphanes:binding and interligand interactions in chromium, molybdenum and tungsten carbonyl complexes." Doctoral thesis, University of Oulu, 2001. http://urn.fi/urn:isbn:9514259866.

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Abstract The first part of this work consisted of a study of the coordination chemistry of aromatic (P,S) and (P,O) heterodonor phosphanes with Cr(CO) 6 , Mo(CO) 6 and W(CO) 6 . The (P,S) donor ligands having one or two o -thiomethoxyphenyl groups, preferred bidentate coordination mode, while the (P,O) donor ligands, having one, two or three o -methoxyphenyls, formed monodentate phosphorus bound complexes. Steric and electronic parameters affecting the coordination chemistry of the phosphanes are discussed for the monodentate complexes. In the second part, triphenylphosphane and 2- and 4-pyridyldiphenylphosphane substituted tungsten tetracarbonyl derivatives was prepared, and attractive intramolecular interactions between the phosphane ligands were studied for both the neutral and the protonated complexes. Hydrogen bonding, π -stacking and cation-π bonding interactions were established, and observed to influence the cis/trans isomerism of the complexes. Cis/trans isomerism could be tuned by protonation, and deprotonation of the pyridyldiphenylphosphane derivatives. All the complexes were characterised by 1 H, 13 C-{ 1 H} and 31 P-{ 1 H} NMR spectroscopy, X-ray crystallography, IR spectroscopy, and either elemental analysis or mass spectroscopy.

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7

Aspley, Catherine J. "Synthesis and photophysics of porphryins linked to metal carbonyl units." Thesis, University of York, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367465.

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8

Alper, Fatma. "Synthesis And Characterization Of Tetracarbonylpyrazinetrimethylphosphitetungsten(0) Complexes." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605569/index.pdf.

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In this study, the effect of a donor ligand on the stabilization of a carbonyl pyrazine tungsten complex was studied. The pentacarbonylpyrazinetungsten(0) complex could be formed from the photolysis of hexacarbonyltungsten(0) in the presence of pyrazine and could be isolated as crystalline solid. However, the complex was found to be unstable in solution, being converted to a bimetallic complex, (CO)5W(pyz)W(CO)5 and free pyrazine molecule. Two complexes exist in solution at equilibrium. The equilibrium constant could be determined by 1H-NMR spectroscopy and found to be 0.0396 at 25&deg<br>C. To test whether the introduction of a second pyrazine ligand might provide stability for the carbonyl-pyrazine-tungsten complex, W(CO)4(pyz)2 was attempted to be synthesized. The cis-W(CO)4(pyz)2 complex could be generated from the thermal substitution reaction of cis-W(CO)4(piperidine)2 with excess pyrazine in dichloromethane. However, this complex could not be isolated because of the lack of stability. The complex could only be identified by IR spectroscopy in solution. To stabilize the pentacarbonylpyrazinetungsten(0) complex, trimethylphosphite was introduced to the complex as a donor ligand. For this purpose, cis-W(CO)4[P(OCH3)3](thf), photogenerated from W(CO)5[P(OCH3)3] in tetrahydrofuran (thf), was reacted with pyrazine. The replacement of tetrahydrofuran with pyrazine (pyz) yielded cis-W(CO)4[P(OCH3)3](pyz). The complex could be isolated from the reaction solution and characterized by means of IR, 1H-, 13C-, 31P-NMR, and Mass spectroscopies. The introduction of P(OCH3)3 has proved that a donor ligand will strengthen the metal-pyrazine bond and thus stabilizes the complex. As a result of this stabilization, the complex could be isolated as the first example of tungsten pyrazine complexes that contain a donor ligand.

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9

0gweno, Aloice 0. "Synthesis, characterization and catalytic application of carbonyl complexes of molybdenum and tungsten in epoxidation of some alkenes." University of the Western Cape, 2010. http://hdl.handle.net/11394/8214.

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>Magister Scientiae - MSc<br>In this thesis we describe the synthesis of several carbonyl complexes of molybdenum and tungsten, compounds (Cl-ClO). The compounds Cl- C4 are zero valent carbonyl complexes containing N-base ligands prepared by following a common synthetic procedure. Compounds Cl and C2 were metal pentacarbonyl of 3-(1-methylpyrrolidin-2-yl) pyridine while C3 and C4 are metal tetracarbonyl complexes of 3, 5- dimethylpyrazole, (M=Mo, W). The compounds C5-C10 are divalent metal carbonyl complexes. Compounds CS and C6 were 3,5-dimethylpyrazole dibromotricarbonyl metal complexes prepared from the dibromotetracarbonyl metal dimers at room temperature while the compounds C7 and C8 were cyclopentadienyl halogenoaryltricarbonyl complexes prepared from the cyclopentadienyl metal dimers. Compounds C9 and ClO were prepared from cyclopentadienyl metal dimers by reacting the [CpM(C0)3r anion with CCl4 to obtain [CpM(C0)3Cl] and further reacted with 3-(1- methylpyrrolidin-2-yl) pyridine. All the compounds, Cl-ClO, were characterized by the standard analytical techniques such as FTIR, 1H, 13C NMR; and UV-Vis spectroscopy. Compound C4 was characterized by X-ray crystallography. The structure is depicted as having a distorted octahedral geometry around the metal centre. The compounds Cl-ClO were then tested towards the epoxidation of selected cyclic and straight chain alkenes. The substrates used were cis-cyclooctene (Cyg), 1-octene (C8) cyclohexene (Cy6), 1-hexene (C6) and styrene (Sty). The epoxidation reactions were carried out at a temperature of 55 °C using tertbutylhydroperoxide (TBHP) as the oxidant and dichloroethane (DCE) as the solvent. The metal carbonyl complexes were pre-activated by first reacting them with the oxidant TBHP to obtain the metal-oxo complexes which are the active compounds for epoxidation reactions. The products were analyzed using GC techniques. The compounds, Cl-ClO showed a promising activity towards epoxidation reactions owing to the high conversions obtained by these compounds. For example, conversions of 81% (1-octene), 90% (cis-cyclooctene) were obtained by compound C5, 87% (cis-cyclooctene-compound C3, 95% (cis-cyclooctene-compound · C7) and 69% (ciscyclooctene- compound C4) for an average period of 24 h. The divalent metal carbonyl complexes showed a higher activity but with poor selectivity towards the expected epoxides compared to the zero valent metal carbonyl complexes.

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10

Gomes, de Lima Bernardes Miriam. "Réactivité de complexes organométalliques mono- et dinucléaires : synthèse de thiolato-composés du molybdène, du tungstène et du cobalt : étude de la formation de liaisons c-c dans la sphère de coordination du métal." Brest, 1986. http://www.theses.fr/1986BRES2008.

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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**(-)

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11

GOMES, DE LIMA LUIS CARLOS. "Reactions d'alcynes cyanes (monocyanoacethylene et dicyanoacethylene), vis-a-vis de complexes organometalliques du fer, du cobalt, du molybdene et du tungstene." Brest, 1986. http://www.theses.fr/1986BRES2009.

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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

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12

Parlier, Andrée. "Application des complexes carbeniques du tungstene a la synthese organique et organometallique." Paris 6, 1987. http://www.theses.fr/1987PA066570.

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13

Achi, Sabah Samira. "Nouvelle voie d'acces aux acides alpha -amines, par catalyse homogene a l'aide de complexes de metaux de transition, synthese de nouveaux complexes phosphores chiraux du tungstene pentacarbonyle." Paris 6, 1987. http://www.theses.fr/1987PA066227.

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14

Bair, Joseph S. "Synthesis and Optical Properties of Four Oligothiophene-Ruthenium Complexes and Synthesis of a Bidentate Ligand for C-F Bond Activation." BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/1031.

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Photovoltaic cells and fluorescence sensing are two important areas of research in chemistry. The combination of photon-activated electron donors with electron acceptors provides a strong platform for the study of optical devices. A series of four oligothiophene-ruthenium complexes has been synthesized. Variation in oligothiophene length and bipyridine substitution allowed comparison of these variables on electronic properties. The longer oligothiophenes display lower energy absorption and emission compared to the shorter ones. Aromatic conjugation appears more complete with para-, rather than meta-, substitution. Oligothiophenes and Ru(bpy)32+ are highly fluorescent individually, but fluorescence is quenched when connected. Bonds of carbon to fluorine are among the strongest single bonds. Single bonds between carbon and hydrogen are also very strong and are ubiquitous. The ability to manipulate these bonds is of great interest to chemists. Two tungsten metal complexes, [6 (perfluorophenyl)bipyridyl] tetracarbonyltungsten and [6-(phenyl)bipyridyl]tetracarbonyltungsten, were prepared for mechanistic C-F and C-H bond activation studies, respectively. These compounds were synthesized through Stille and Suzuki coupling of commercial reagents. Ligands were then bound to tungsten to form the tetracarbonyl complexes.

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15

Bornet, Céline. "Synthèse et réactivité de nouveaux macrocycles séléniés." Dijon, 1998. http://www.theses.fr/1998DIJOS043.

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Ce mémoire apporte une contribution à la synthèse et à l'étude des propriétés complexantes de nouveaux macrocycles séléniés. Ceux-ci ont été pour la plupart construits autour d'entités rigides de type orthodisélénophénylène obtenues au départ d'un complexe du zirconium préparé antérieurement au laboratoire. Une chaine oxygénée a été dans chaque cas utilisée pour réaliser la cyclisation ou pour jouer le rôle d'espaceur entre deux entités. A des fins de comparaisons, d'autres systèmes construits au départ de ligands orthothio-séléno ou orthothio-tellurophénylène ont également été synthétisés. Les ligands obtenus ont été caractérisés par spectrométrie de masse et RMN multinoyaux. La structure de trois d'entre eux a été déterminée par diffraction de rayons X. La réactivité des différents macrocycles synthétisés a été testée vis-à-vis de divers ions métalliques (palladium (ii), platine (ii), argent (i), or (i) et mercure (ii)), ainsi que du molybdène et tungstène hexacarbonyle. Des complexes stables ont ainsi été obtenus dans lesquels les métaux sont fixes sélectivement sur les atomes de sélénium. Deux structures ont été résolues par diffraction de rayons X. En particulier, le premier complexe cationique du palladium associant deux macrocycles séléniés par l'intermédiaire d'un atome métallique a pu être synthétisé et caractérisé. Parmi les possibilités offertes par les ligands synthétisés, nous avons pu montrer que les macrocycles tétraséléniés sont aptes à extraire des ions mercure (ii) d'une solution aqueuse. Ils permettent également la complexation de molécules polaires telles que l'acétonitrile ou le maléonitrile.

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16

Huang, Chih-Chiang, and 黃治強. "Synthesis and Reactivity of the 1,8-Cyclotetradecadiyne Carbonyl Tungsten Complexes." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/59cvuh.

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17

"SYNTHESIS AND CHARACTERIZATION OF CARBONYL - TUNGSTEN(0) COMPLEXES OF [N,N'-BIS(FERROCENYLMETHYLENE)ETHYLENEDIAMINE]." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606101/index.pdf.

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18

Lin, Jia-Shyang, and 林嘉祥. "1. Synthesis of ACE inhibitor-Enalapril 2. Studies on Tungsten Propargyl Complexes: Application to Carbonyl Cyclization Reaction." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/72266922207148220804.

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碩士<br>國立清華大學<br>化學系<br>86<br>Enalapril為一種已上市之ACE抑制藥劑，其結構中含有L-丙氨醯-L-脯氨酸雙的片斷。然而以往合成Enalapril的方法不是反應條件激烈，使用特殊試劑，便是總產率偏低。本篇論文主要研究的重點便在於改進以上的缺點以期得到更好的結果。利用Michael加成反應，可將L-丙氨酸引入4- 苯基-2-丁烯酸乙酯的雙鍵上，再利用鍵的縮合反應，便可以將L-脯氨酸的胺基與N-(1-S-乙氧羰基-3-苯丙基)-L-丙氨酸的羧基縮合成鍵。經由本合成方法，可避免使用較激烈的反應條件及特殊的反應試劑，不啻為合成Enalapril另一可行的方法。另一方面在有機金屬鎢-h1-丙炔基化合物反應的研究上，我們發現具多電子的苯環化合物在推電子基團的輔助及質子酸的存在的條件下可與鎢上的羰基進行一親核性的羰基化環化反應而形成一具有羰基的環化產物。且由於苯環上的電子效應及立體效應，對於此類羰基化環化反應的反應性及反應位向有著極大的影響。

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19

Ioachim, Elena. "Des nouvelles classes de photosensibilisateurs : nouveaux complexes métalliques à base de 4,4'-bipyrimidine substituée." Thesis, 2005. http://hdl.handle.net/1866/16781.

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