Download or read book Transition Metal Complexes with P N Ligands and Silylenes Synthesis and Catalytic Studies written by Eva Neumann and published by Cuvillier Verlag. This book was released on 2006-02-15 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: The term ligand [latin, ligare = bind] has its origin in coordination chemistry. It denotes a molecule that is able to bind to a metal center in most cases via one or several free electron pairs.[1] Ligands can be described by the number of electron-pair donor atoms as monodentate, bidentate, tridentate etc. ligands. The latter are also called chelating ligands [greek, chele = (crab’s) claw]. A typical classification of ligands is according to their electronic properties. They serve either as a σ-donating, σ-donating/π-accepting, or σ,π-donating/π-accepting ligands.[2] A more practical, often encountered approach is the classification of ligands according to their donor atoms, especially when larger molecules and molecules containing heteroatoms are regarded (compare 1.2). Coordination chemistry was already established in the 19th century. In 1893 Alfred Werner suggested an octahedral arrangement of ligands coordinated to a central metal ion for many compounds. This explained, for example, the appearance and reactivity of four different cobalt(III) complexes (Figure 1.1), when CoCl2 is dissolved in aqueous ammonia and then oxidized by air to the +3 oxidation state. The formulas of these complexes can be written as depicted in Figure 1.1. Werner’s work was rewarded with the Nobel prize in 1913.[3]

Download or read book N heterocyclic Silyl and Silylene Metal Complexes Within a PSIP Framework written by Amy Marie Jehl and published by . This book was released on 2019 with total page 237 pages. Available in PDF, EPUB and Kindle. Book excerpt: N-heterocyclic carbenes (NHC) are strong Lewis bases that have demonstrated broad utility as ligands for transition metal (TM) catalysts. Silicon analogues, N-heterocyclic silylenes (NHSi), are comparatively less well studied. The decreased [Pi]-[pi] overlap between the Si 3p orbital and adjacent nitrogen lone pairs creates a more accessible vacant orbital on Si, resulting in increased ambiphilic character. When bound to a transition metal, this empty orbital presents an opportunity to cooperatively bind and activate substrate molecules. To increase the stability of a potential metal-silylene complex we targeted the diphosphine ligand precursor 1,2-bis(R2PCH2NCH2)C6H4 (R = alkyl or aryl), first reported by Yamashita and Nozaki in the construction of a boron-anchored pincer. Reported here are (PCy)2Si pincer ligands and their TM-silylene complexes for small molecule activation.

Download or read book Syntheses and Reactivity Studies of Transition Metal Complexes Featuring Metal Main Group Multiple Bonds written by Meg E. Fasulo and published by . This book was released on 2012 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ruthenium triflate complex Cp*(PiPr3)RuOTf (1) was generated from the reaction of Cp*(PiPr3)RuCl with Me3SiOTf in dibutyl ether. Complex 1 reacted with primary and secondary silanes to produce a family of Ru(IV) silyl dihydride complexes of the type Cp*(PiPr3)Ru(H)2(SiRR'OTf) (3 - 12). Structural analyses of complexes 8 (R = R' = Ph) and 12 (R = R' = fluorenyl) revealed the presence of a tetrahedral silicon center and a four-legged piano stool geometry about ruthenium. Anion abstraction from Cp*(PiPr3)Ru(H)2(SiHROTf) by [Et3Si*toluene][B(C6F5)4] afforded hydrogen-substituted cationic ruthenium silylene complexes [Cp*(PiPr3)Ru(H)2(=SiHR)][B(C6F5)4] (R = Mes (13), R = Si(SiMe3) (14)) that display a significant Ru - H ... Si interaction, as indicated by relatively large 2JSiH coupling constants (2JSiH = 58.2 Hz (13), 2JSiH = 37.1 Hz (14)). The syntheses of secondary silylene complexes [Cp*(PiPr3)Ru(H)2(=SiRR')][B(C6F5)4] (R = R' = Ph (15); R = Ph, R' = Me (16), R = R' = fluorenyl (17)) were also achieved by anion abstraction with [Et3Si*toluene][B(C6F5)4]. Complexes 15 - 17 do not display strong Ru - H ... Si secondary interactions, as indicated by very small 2JSiH coupling constant values. The cationic ruthenium silylene complex [Cp*(PiPr3)Ru(H)2(SiHMes)] [CB11H6Br6], a catalyst for olefin hydrosilations with primary silanes, was isolated and characterized by X-ray crystallography. Relatively strong interactions between the silylene Si atom and Ru-H hydride ligands appear to reflect a highly electrophilic silicon center. Kinetic and mechanistic studies on hydrosilations with this catalyst reveal a fast, initial addition of the Si-H bond of the silylene complex to the olefin. Subsequent migration of a hydride ligand to silicon produces a 16-electron intermediate, which can be trapped by olefin, resulting in inhibition of catalysis, or intercepted by the silane substrate. The latter reaction pathway, involving oxidative addition of the Si-H bond and a somewhat concomitant loss of product, is the rate-determining step in the catalytic cycle. Reactions of the cationic ruthenium silylene complexes [Cp*(PiPr3)Ru(H)2(=SiRR')][B(C6F5)4] (R = Mes, R' = H, 1; R = R' =Ph, 2) with alkenes, alkynes, ketones, and Lewis bases were explored. Addition of 1-hexene, 3,3-dimethylbut-1-ene, styrene, and cyclopentene to 1 afforded the disubstituted silylene products [Cp*(PiPr3)Ru(H)2(=SiMesR)][B(C6F5)4] (R = Hex, 3; R = CH2CH2tBu, 4; R = CH2CH2Ph, 5; R = C5H9, 6). Analogous reactions with 2-butyne and 3,3-dimethylbut-1-yne yielded the vinyl-substituted silylene complexes [Cp*(PiPr3)Ru(H)2(=Si(CR=CHR')Mes)][B(C6F)4] (R = R' = Me, 7; R = H, R' = tBu, 8). Complex 1 undergoes reactions with ketones to give the heteroatom-substituted silylene complexes [Cp*(PiPr3)Ru(H)2(=Si(OCHPhR)Mes)][B(C6F)4] (R = Ph, 9; R = Me, 10). Interestingly, complexes 3 - 8 display a weak interaction between the hydride ligands and the silicon center, while 9 and 10 exhibit a relatively large interaction (as determined by 2JSiH values). The reaction of isocyanates with 1 resulted in the silyl complexes [Cp*(PiPr3)Ru(H)2(Si(Mes)[n2-O(CH)(NC6H4R)][B(C6F5)4] (R = H, 11; R = CF3, 12), and an intermediate in this transformation is observed. Complex 2 was subjected to various Lewis bases to yield the base-stabilized silylene complexes [Cp*(PiPr3)Ru(H)2(SiPh2*L)][B(C6F)4] (L = DMAP, 13; L = Ph2CO, 14; L = PhCONH2, 15; L = NHMePh, 16, L = tBuSONH2, 18) and the reaction of 1 with NHMePh gave [Cp*(PiPr3)Ru(H)2(SiHMes*NHMePh)][B(C6F)4]. The cationic germylene complex [Cp*(PiPr3)Ru(H)2(=GeMes2)][OTf] (1) was synthesized from the reaction of Cp*(PiPr3)RuOTf with H2GeMes2, and addition of DMAP to 1 yielded the neutral germylene complex [Cp*(PiPr3)Ru(H)(=GeMes2) (2). The reaction of H3GeTrip and Cp*(PiPr3)RuCl gave the germyl complex Cp*(PiPr3)Ru(H)2(GeHTripCl) (3), which undergoes a reaction with Li(Et2O)2[B(C6F5)4] to afford the cationic H-substituted germylene complex [Cp*(PiPr3)Ru(H)2(=GeHTrip)][B(C6F5)4] (4). Addition of 1-hexene, 3,3-dimethylbut-1-ene, styrene, and allyl chloride to 4 afforded the disubstituted germylene products [Cp*(PiPr3)Ru(H)2(=GeTripR)][B(C6F5)4] (R = Hex, 5; R = CH2CH2Ph, 6; R = CH2CH2tBu, 7; R = CH2CH2CH2Cl, 8). Analogous reactions with 2-butyne and 3,3-dimethylbut-1-yne yielded the vinyl-substituted germylene complexes [Cp*(PiPr3)Ru(H)2(=Ge(CR=CHR')Trip)][B(C6F)4] (R = H, R' = tBu, 9; R = R' = Me, 10). New di(phosphine)-supported rhodium and iridium silyl complexes were synthesized. Reactions of the di(t-butylphosphino)ethane complex (dtbpe)Rh(CH2Ph) with Ph2SiH2 and Et2SiH2 resulted in isolation of (dtbpe)Rh(H)2(SiBnPh2) (1, Bn = CH2Ph) and (dtbpe)Rh(H)2(SiBnEt2) (2), respectively. Both 1 and 2 display strong interactions between the rhodium hydride ligands and the silyl ligand, as indicated by large 2JSiH values (44.4 and 52.1 Hz). The reaction of (dtbpm)Rh(CH2Ph) (dtbpm = di(t-butylphosphino)methane) with Mes2SiH2 gave the pseudo-three-coordinate Rh complex (dtbpm)Rh(SiHMes2) (3), which is stabilized in the solid state by agostic interactions between the rhodium center and two C - H bonds of a methyl substituent of a mesityl group. The analogous germanium compound (dtbpm)Rh(GeHMes2) (4) is also accessible. Complex 3 readily undergoes reactions with diphenylacetylene, phenylacetylene, and 2-butyne to give the silaallyl complexes (dtbpm)Rh[Si(CPh=CHPh)Mes2] (5), (dtbpm)Rh[Si(CH=CHPh)Mes2] (7), and (dtbpm)Rh(Si(CMe=CHMe)Mes2) (8) via net insertions into the Si - H bond. The germaallyl complexes (dtbpm)Rh[Ge(CPh=CHPh)Mes2] (6) and (dtbpm)Rh[Ge(CMe=CHMe)Mes2] (9) were synthesized under identical conditions starting from 4. The reaction of (dtbpm)Rh(CH2Ph) with 1 equiv of TripPhSiH2 yielded (dtbpm)Rh(H)2[5,7-diisopropyl-3-methyl-1-phenyl-2,3-dihydro-1H-silaindenyl-kSi] (11), and catalytic investigations indicate that both (dtbpm)Rh(CH2Ph) and 11 are competent catalysts for the conversion of TripPhSiH2 to 5,7-diisopropyl-3-methyl-1-phenyl-2,3-dihydro-1H-silaindole. A dtbpm-supported Ir complex, [(dtbpm)IrCl]€2, was used to access the dinuclear bridging silylene complexes [(dtbpm)IrH](SiPh2)(Cl)2[(dtbpm)IrH] (12) and [(dtbpm)IrH](SiMesCl)( -Cl)(H)[(dtbpm)IrH] (13). The reaction of [(dtbpm)IrCl]2 with a sterically bulky primary silane, (dmp)SiH3 (dmp = 2,6-dimesitylphenyl), allowed isolation of the mononuclear complex (dtbpm)Ir(H)4(10-chloro-1-mesityl-5,7-dimethyl-9,10-dihydrosilaphenanthrene-Si) (14), in which the dmp substituent has undergone C-H activation. The dichloride complex Cp*(Am)WCl2 (1, Am = [(iPrN)2CMe]- ) reacted with the primary silanes PhSiH3, (p-tolyl)SiH3, (3,5-xylyl)SiH3, and (C6F5)SiH3 to produce the W(VI) (silyl)trihydrides Cp*(Am)W(H)3(SiHPhCl) (2), Cp*(Am)W(H)3(SiHTolylCl) (3), Cp*(Am)W(H)3(SiHXylylCl) (4), and Cp*(Am)W(H)3[SiH(C6F5)Cl] (5). In an analogous manner, 1 reacted with PhSiH2Cl to give Cp*(Am)W(H)3(SiPhCl2) (6). Complex 6 can alternatively be quantitatively produced from the reaction of 2 with Ph3CCl. NMR spectroscopic studies and X-ray crystallography reveal an interligand H ... Si interaction between one W - H and the chlorosilyl group, which is further supported by DFT calculations. Complexes of Ru(II) containing the pincer ligand [-N(2-PPh2-4-Me-C6H3)2] (PNPPh) were prepared. The complex (PNPPhH)RuCl2 (1) was treated with 2 equiv AgOTf to produce the triflate complex (PNPPhH)Ru(OTf)2 (2). Complex 1 was also treated with an excess of NaBH4 to give a bimetallic complex [(PNPPh)RuH3]2 (3). A number of methods, including X-ray crystallography, NMR spectroscopy, and computational studies, were used to probe the structure of 3. Addition of Lewis bases to 3 resulted in octahedral complexes containing a hydride ligand trans to a dihydrogen ligand.

Download or read book Metal Ligand Multiple Bonds written by William A. Nugent and published by Wiley-Interscience. This book was released on 1988-11-14 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: The only comprehensive one-volume text/reference on metal-ligand multiple bonds. Stresses the unified nature of the field and includes handy new tabulations of data. The flow within each subtopic is oxygen to nitrogen to carbon. Coverage is up-to-date--virtually every subtopic leads to interesting questions for future research. Presents information otherwise scattered through hundreds of publications.

Download or read book Transition Metal Complexes of Neutral Eta1 Carbon Ligands written by Remi Chauvin and published by Springer Science & Business Media. This book was released on 2010-01-12 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is part of a series that gives the broad scientific readership a comprehensive summary and critical overview of specific topics in the field of organometallic chemistry. This text focuses on transition metal complexes of neutral eta1-carbon ligands.

Download or read book Synthesis Characterization and Reactivity of Transition Metal Complexes Containing Multi donor Ligands written by John C. Linehan and published by . This book was released on 1986 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Transition Metal Complexes of Phosphorus Arsenic and Antimony Ligands written by Charles Andrew McAuliffe and published by John Wiley & Sons. This book was released on 1973 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Synthesis and Chemistry of Transition metal Complexes Incorporating Sila and Germaaromatic Ligands written by Jeffrey Michael Dysard and published by . This book was released on 2000 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Reactivity of Transition Metal Complexes Using Ligands Capable of Variable Electron Donation written by Gregory A. Marinelli and published by . This book was released on 1992 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Organophosphorus Chemistry written by Viktor Iaroshenko and published by John Wiley & Sons. This book was released on 2019-01-07 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Filling the gap for an up-to-date reference that presents the field of organophosphorus chemistry in a comprehensive and clearly structured way, this one-stop source covers the chemistry, properties, and applications from life science and medicine. Divided into two parts, the first presents the chemistry of various phosphorus-containing compounds and their synthesis, including ylides, acids, and heterocycles. The second part then goes on to look at applications in life science and bioorganic chemistry. Last but not least, such important practical aspects as 31P-NMR and protecting strategies for these compounds are presented. For organic, bioinorganic, and medicinal chemists, as well as those working on organometallics, and for materials scientists. The book, a contributed work, features a team of renowned scientists from around the world whose expertise spans the many aspects of modern organophosphorus chemistry.

Download or read book Spatially Well defined Silylene Transition metal Complexes in Selective Catalysis written by Shweta Kalra and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Metallocenes in Regio and Stereoselective Synthesis written by Marko Hapke and published by Springer. This book was released on 2024-06-20 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the latest synthetic protocols for the assembly of functionalized Cp ligands and their transition metal complexes. Cyclopentadienyl (Cp) complexes of transition metals belong to the most important classes of transition metal complexes with tightly bound ligands in the coordination sphere since their discovery in the middle of the last century. Even though they have been known for a long time, this field constantly evolves to deliver novel modified Cp ligands and complexes and to blossom into new fields of application. Beside the synthesis of ligands and metal complexes this book concentrates on novel and prospering fields of their application in organic synthesis. In this respect the Cp complexes have been applied to induce and catalyze various significant chemical transformations such as new C-C bond formation involving unsaturated substrates (e.g. cyclotrimerizations, cycloadditions, carbometallations, etc.), C-H bond and C-C bond activations followed by subsequent reactions (e.g. arylation, alkenylations, annulations, etc.), as well as many other processes. This volume also covers the recent development and application of chiral Cp complexes in enantioselective synthesis.

Download or read book Exploratory Synthesis of New Transition Metal Complexes with Polychalcogenide Ligands Using Conventional Solution Reactions and Hydro solvo thermal Techniques written by Songping Huang and published by . This book was released on 1993 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Transition Metal Complexes of Cyclic Polyolefins written by G. Deganello and published by . This book was released on 1979 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Catalysis with Earth abundant Elements written by Uwe Schneider and published by Royal Society of Chemistry. This book was released on 2020-10-30 with total page 431 pages. Available in PDF, EPUB and Kindle. Book excerpt: Considering the limited resources of our planet, earth-abundant elements will have to be explored increasingly in the future. This book highlights the uses of the most earth-abundant elements in catalysis and will be of interest to graduates, academic researchers and practitioners in catalysis.

Download or read book Transition Metal Complexes with Some Tertiary Phosphine Ligands written by Najeeb Abdul Munem Al-Salem and published by . This book was released on 1978 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Transition Metals in Supramolecular Chemistry written by L. Fabbrizzi and published by Springer. This book was released on 1994-10-31 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the pioneering publications on coordination chemistry by Lehn and Pedersen in the late 1960s, coupled with the more orthodox interest from the transition metal chemists on template reactions (Busch, 1964), the field of supramolecular chemistry has grown at an astonishing rate. The use of transition metals as essential constituents of multi-component assemblies has been especially sharp in recent years, since the metals are prone to quick and reversible redox changes, and there is a wide variety of metal--ligand interactions. Such properties make supramolecular complexes of transition metal ions suitable candidates for exploration as light--energy converters and signal processors. Transition Metals in Supramolecular Chemistry focuses on the following main topics: (1) metal controlled organization of novel molecular assemblies and shapes; (2) design of molecular switches and devices operating through metal centres; (3) supramolecular catalysts that mimic metalloenzymes; (4) metal-containing sensory reagents and supramolecular recognition; and (5) molecular materials that display powerful electronic, optoelectronic and magnetic properties.