Author: Michelle GallagherPublisher:
ISBN:
Category :
Languages : en
Pages : 260
Book Description
Synthesis, Structure, and Reactivity of Low Valent Ruthenium Complexes Bearing Bis(imino)pyridyl Ligands
Author: Michelle GallagherReactivity of a Ruthenium Silyl Choride Complex Bearing a Bisiminopyridyl Ligand
Author: Noah FrankChemistry of Ruthenium Complexes Incorporating the Doubly-linked Bis(dimethylsilylcyclopentadienyl) Ligand
Author: David Peter KleinPublisher:
ISBN:
Category :
Languages : en
Pages : 194
Book Description
This dissertation describes three investigations of the dinuclear ruthenium complex, [([eta]5-C5H3)2(SiMe2)2]Ru2(CO)4: (1) its use as a catalyst for the hydroamination of alkynes by a new mechanism, (2) its reactions with H2 to give new ruthenium clusters containing bridging hydride ligands, and (3) the determination of thermodynamic and kinetic acidities of two related complexes [([eta]5-C5H3)2(SiMe2)2]Ru2(CO)3[P(OR)3]HBF4− (R= Me, Ph). A fundamentally new mechanism for alkyne hydroamination catalyzed by the ruthenium complex, [([eta]5-C5H3)2(SiMe2)2]Ru2(CO)3(C2H4)H+BF4−, has been proposed. Many of the intermediates in the catalytic cycle have been isolated and/or characterized spectroscopically and found to react according to the proposed mechanism. The catalyst activity is terminated as a result of the isomerization of a bridging alkyne ligand in a key intermediate in the catalytic cycle. The butterfly cluster, [([eta]5-C5H3)2(SiMe2)2]2Ru4(CO)3H4, and the square planar cluster, [([eta]5-C5H3)2(SiMe2)2]2Ru4(CO)4H4, have been isolated from the photochemical reaction of H2 with the doubly-linked dicyclopentadienyl complex, [([eta]5-C5H3)2(SiMe2)2]Ru2(CO)4, in benzene. Wavelength-dependent photolysis studies suggest that the first step in the reaction of [([eta]5-C5H3)2(SiMe2)2]Ru2(CO)4 with H2 involves metal-metal bond cleavage. The reaction of the protonated phosphite complexes, [([eta]5-C5H3)2(SiMe2)2]Ru2(CO)3[P(OR)3]H+BF4− (R= Me, Ph), with tertiary amines (DABCO, 4-methylmorpholine, NEt3, N(n-Bu)3) results in clean deprotonation of the metal-metal bond by the amine. Equilibrium measurements show that the P(OPh)3 complex is more acidic than the P(OMe)3 complex. The rates of deprotonation of the phosphite complexes have been determined and follow the rate law: Rate = k1[complex] + k2[amine][complex]. Comparisons of the k2 rate constants reveal that the reactions are much more sensitive to the steric properties of the amine and metal complex than to electronic factors.
Ruthenium in Organic Synthesis
Author: Shun-Ichi MurahashiPublisher: John Wiley & Sons
ISBN: 3527605797
Category : Science
Languages : en
Pages : 398
Book Description
In this comprehensive book, one of the leading experts, Shun-Ichi Murahashi, presents all the important facets of modern synthetic chemistry using Ruthenium, ranging from hydrogenation to metathesis. In 14 contributions, written by an international authorship, readers will find all the information they need about this fascinating and extraordinary chemistry. The result is a high quality information source and a indispensable reading for everyone working in organometallic chemistry. From the contents: Introduction (S.-I. Murahashi) Hydrogenation and Transfer Hydrogenation (M. Kitamura and R. Noyori) Oxidations (S.-I. Murahashi and N. Komiya) Carbon-Carbon Bond Formations via Ruthenacycle Intermediates (K. Itoh) Carbon-Carbon Bond Formation via pi-Allylruthenium Intermediates (T. Mitsudo) Olefin Metathesis (R. H. Grubbs) Cyclopropanation (H. Nishiyama) Nucleophilic Addition to Alkynes and Reactions via Vinylidene Intermediates (P. Dixneuf) Reactions via C-H Activation (N. Chatani) Lewis Acid Reactions (E. P. Kundig) Reactions with CO and CO2 (T. Mitsudo) Isomerization of Organic Substrates Catalyzed by Ruthenium Complexes (H. Suzuki) Radical Reactions (H. Nagashima) Bond Cleavage Reactions (S. Komiya)
Transition Metal-Dinitrogen Complexes
Author: Yoshiaki NishibayashiPublisher: John Wiley & Sons
ISBN: 352734425X
Category : Science
Languages : en
Pages : 496
Book Description
A comprehensive book that explores nitrogen fixation by using transition metal-dinitrogen complexes Nitrogen fixation is one of the most prominent fields of research in chemistry. This book puts the focus on the development of catalytic ammonia formation from nitrogen gas under ambient reaction conditions that has been recently repowered by some research groups. With contributions from noted experts in the field, Transition Metal-Dinitrogen Complexes offers an important guide and comprehensive resource to the most recent research and developments on the topic of nitrogen fixation by using transition metal-dinitrogen. The book is filled with the information needed to understand the synthesis of transition metal-dinitrogen complexes and their reactivity. This important book: -Offers a resource for understanding nitrogen fixation chemistry that is essential for explosives, pharmaceuticals, dyes, and all forms of life -Includes the information needed for anyone interested in the field of nitrogen fixation by using transition metal-dinitrogen complexes -Contains state-of-the-art research on synthesis of transition metal-dinitrogen complexes and their reactivity in nitrogen fixation -Incorporates contributions from well-known specialists and experts with an editor who is an innovator in the field of dinitrogen chemistry Written for chemists and scientists with an interest in nitrogen fixation, Transition Metal-Dinitrogen Complexes is a must-have resource to the burgeoning field of nitrogen fixation by using transition metal-dinitrogen complexes.
Chemical and Redox Non-innocence in Iminopyridine and Bis(imino)pyridine Aluminum(III) Complexes Including Polar Bond Activation and Catalytic Dehydrogenation by ([superscript Ph]I2P2−)Al(THF)H ([superscript Ph]I2P
![Chemical and Redox Non-innocence in Iminopyridine and Bis(imino)pyridine Aluminum(III) Complexes Including Polar Bond Activation and Catalytic Dehydrogenation by ([superscript Ph]I2P2−)Al(THF)H ([superscript Ph]I2P PDF](https://books.google.com/books/content/images/frontcover/MIdAswEACAAJ?fife=w80-h100)
Author: Thomas Winfield MyersPublisher:
ISBN: 9781321212495
Category :
Languages : en
Pages :
Book Description
This dissertation discusses the synthesis, reactivity and characterization of iminopyridine and bis(imino)pyridine complexes of aluminum and other electrophilic main group metal ions. It is shown that aluminum complexes of iminopyridine ligands can undergo stoichiometric redox transformations while aluminum complexes of bis(imino)pyridine ligands can facilitate heterolytic substrate activation and catalytic dehydrogenation reactions. In chapter 2, the reaction of disulfides, nitrogen group transfer reagents, and zinc(II) salts with [Na(THF)6][(IP2−)2Al] (2.1c) (IP = 2,6-bis(isopropyl)-N-(2-pyridinyl-methylene)phenylamine) affords aluminum complexes of the form (IP−)2AlX (X = Cl 2.2, [mu]2-SSCN(CH3)2 2.4, SCH3 2.5, NaNTs 2.6, CCPh 2.7, N3 2.8, SPh 2.9, and NHPh 2.10). Additionally, the oxidation of (IP−)2Al(Me) (2.3) by single electron oxidants leads to formation of [(IP−)(IP)Al(Me)]+. When TrBPh4 (Tr = triphenylmethyl) is employed as the oxidant, carbon-carbon coupling between one of the IP ligands and the Tr group is observed to form [(TrIP)(IP)Al(Me)]+ (2.11). This bond formation can be reversed when bulkier anions are added, or can be avoided by using TrB(C6F5)4 and TrBAr[superscript F] as the one electron oxidants. In chapter 3, the formation of Al(III) and Ga(III) oxo intermediates are proposed resulting from the oxidation of [(IP2−)2M]− (M = Al, Ga) with pyO (pyO = pyridine-N-oxide). These reactive intermediates homolytically and heterolytically cleave C-H bonds to form [Na(DME)(THF)][(IP2−)(IP−)Al(OH)] (3.3) and (IP−)2M(OH) (M = Al 3.4, Ga 3.7). The identity of the counter cation directs the reactivity of [(IP2−)2Al]−. When [Na(DME)3][(IP2−)2Al] is employed, C-H activation of solvent is observed, while when [Bu4N][(IP2−)2Al] is employed proton abstraction from Bu4N+ is observed. The oxidation of [(IP2−)2Ga]− by pyO leads to acid base chemistry when either Na+ or Bu4N+ is employed as the counter cation. The reaction of 3.4 and 3.7 with CO2 leads to formation of [(IP−)2M]2([mu][eta]1:[kappa]2-OCO2) (M = Al 3.10, Ga 3.11). Reduction of 3.10 and 3.11 with alkali or alkali earth metals and subsequent oxidation allows for the reformation of 3.4 and 3.7. In chapter 4, the reduction of [superscript Me]IP[subscript Mes] ([superscript Me]IP[subscript Mes] = 2,6-bis(isopropyl)-N-(2-(5-mesityl-pyridinyl)-methylene)phenylamine) with sodium metal followed by metathesis with MCl[subscript n]X[subscript 3-n] (M = Al, Ga, X = Cl, CH3) leads to the formation of ([superscript Me]IP[subscript Mes−)MX2 (M = Al, X = Cl, 4.1a, 4.2a; M = Ga, X = Cl 4.5), ([superscript CH2]IP[subscript Mes]−)AlX2 (X = Cl, 4.1b, 4.2b), ([superscript Me]IP[subscript Mes]2−)MX(OEt2) (M = Al, X = Cl, 4.3, 4.4; M = Ga, X = Cl 4.6) . Unlike the IP ligand system, only one [superscript Me]IP[subscript Mes] ligand coordinates to the metal center in these complexes. Selective deprotonation of the [superscript Me]IP[subscript Mes] ligand is observed in ether solvents, while selective reduction is observed in alkane and aromatic solvents. In chapter 5, complexes of bis(imino)pyridine ligands with aluminum are presented. Reduction of [superscript Ph]I2P ([superscript Ph]I2P = 2,6-(2,6-[superscript i]Pr2-C6H3N=CPh)2C5H3N) by 2 equivalents of sodium metal followed by salt metathesis with AlCl2X (X = Cl, H) affords ([superscript Ph]I2P2−)AlX(THF) (X = Cl 5.1, H 5.2a) and ([superscript Ph]I2P2−)AlH (5.2b). The [superscript Ph]I2P2− ligands in these complexes are shown to be chemically non-innocent. The addition of polar N-H and O-H bonds across the aluminum-amido bonds leads to the formation of ([superscript Ph]HI2P2−)AlH(X) (X = NHDipp 5.3a, NHPh 5.3b, [mu]-O 5.5, OPh 5.8) (Dipp = 2,6-diisopropylphenyl). 5.2b also catalyzes the dehydrogenative coupling of benzylamine with 3.5 turnovers over 24 hours. In chapter 6, complexes of the form ([superscript Ph]I2P2−)AlX(THF) (X = H, Me) are shown to be active catalysts for the selective dehydrogenation of formic acid with an initial TOF of up to 5200 hr−1 and up to 2200 total turnovers observed. The mechanism of the transformation is examined through a series of stoichiometric reactions. In the presence of formic or acetic acid, the [superscrpt Ph]I2P2− ligand is protonated at both the amido nitrogen and at the ipso carbon position effectively hydrogenating one of the imine arms of the ligand. The Al(III) complexes of the [superscript Ph]HI2P− and [superscript Ph]H2I2P forms of the ligand favor [beta]-hydride abstraction from formate, while the Al(III) complexes of the [superscript Ph]I2P2− form of the ligand favors the reverse reaction: insertion of CO2 into the Al-H bond. The liberation of CO2 from formate is investigated through a series of deuterium labeling studies which show [beta]-hydride transfer from formate to the aluminum center. Finally, in chapter 7, the variety of electronic states adopted by complexes of methyl-substituted bis(imino)pyridine ligands is discussed. Reduction of [superscript Me]I2P ([superscript Me]I2P = 2,6-bis(1-methylethyl)-N-(2-pyridinylmethylene)phenylamine) with sodium metal leads to the formation of ([superscript Me]I2P−)Na(OEt2) (7.1). Reduction of [superscript Me]I2P by sodium metal followed by salt metathesis with MgCl2, Mg(OTf)2, AlCl3, and AlCl2H affords [([superscript Me]I2P2−)Mg(THF)](MgCl2) (7.2), ([superscript Me]I2P2−)Mg(THF)2 (7.3), ([superscript Me]I2P−)AlCl2 (7.4), ([superscript Me]I2P2−)AlCl(THF) (7.5) and ([superscript Me]I2P2−)AlH(THF) (7.6), respectively. The electronic states of 7.1 to 7.6 are shown to be dependent on the reaction conditions used to synthesize the complexes with certain conditions leading to dimer formation. Initial reactivity studies with 7.5 and 7.6 are discussed.
Synthesis and Characterization of Polypyridyl Ligands and Ruthenium(II) Complexes Based on the Reactivity of 4,5-diazafluorenone in the Presence and Absence of Ruthenium(II) Ion
Author: Youxiang WangDissertation Abstracts International
Author: Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 854
Book Description
Half-sandwich Complexes of Ruthenium Supported by N-Heterocyclic Carbene Ligands
Author: Van Hung MaiPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
This thesis presents the preparation and catalytic reactivity of novel half-sandwich ruthenium complexes supported by N-Heterocyclic Carbene (NHC) ligands. The cationic half-sandwich ruthenium complexes [Cp(IPr)Ru(CH3CN)2]+ show interesting reactivities toward the transfer hydrogenation of different unsaturated substrates, such as ketones, olefins, N-heterocycles, and nitriles. Kinetic studies disclose that a neutral trishydride ruthenium complex is actually involved in the catalytic cycle, playing the role as a resting state. Further investigations on the sub-class of trishydride ruthenium complexes bearing NHC ligands (Cp'(NHC)RuH3) reveal that these complexes have an unusual and great catalytic performance toward the hydrodefluorination (HDF) of fluorinated aromatic and aliphatic compounds. The combined kinetic studies, cross-over experiments and rate law analysis suggest an unusual mechanistic pathway for the Cp*(IPr)RuH3 catalyzed HDF. This study is one of the rare examples where isopropanol is employed as a reducing agent for the metal-mediated HDF reaction. A class of silyl dihydride ruthenium complexes, derived from Cp(IPr)RuH3 are prepared. These silyl hydrido derivatives are great compounds for the study of the inter ligand hypervalent interaction (IHI), an interesting phenomenon for many non-classical silane complexes. This study also suggests that the replacement of phosphines by their isolobally analogous NHC ligands result in stronger IHI interactions in the corresponding compounds. Another type of non-classical interaction was systematically scrutinized in a ii series of new cationic and neutral silane sigma complexes of ruthenium bearing different silyl moieties. These new NHC-supported ruthenium complexes allow for direct comparation with the known phosphine analogues, which reveals interplay of steric and electronic factors on the extent of Si-H complexation to metal and the extent of additional interligand interactions between Ru-Cl and chlorosilane ligand. Finally, new trishydride ruthenium complexes bearing NHC ligands (Cp'(NHC)RuH3) catalyze the H/D exchange reaction of various N-heterocycle substrates; their catalytic performance can be considered as one of the mildest, and most efficient approaches.
Pincer Compounds
Author: David Morales-MoralesPublisher: Elsevier
ISBN: 0128129328
Category : Science
Languages : en
Pages : 756
Book Description
Pincer Compounds: Chemistry and Applications offers valuable state-of-the-art coverage highlighting highly active areas of research—from mechanistic work to synthesis and characterization. The book focuses on small molecule activation chemistry (particularly H2 and hydrogenation), earth abundant metals (such as Fe), actinides, carbene-pincers, chiral catalysis, and alternative solvent usage. The book covers the current state of the field, featuring chapters from renowned contributors, covering four continents and ranging from still-active pioneers to new names emerging as creative strong contributors to this fascinating and promising area. Over a decade since the publication of Morales-Morales and Jensen's The Chemistry of Pincer Compounds (Elsevier 2007), research in this unique area has flourished, finding a plethora of applications in almost every single branch of chemistry—from their traditional application as very robust and active catalysts all the way to potential biological and pharmaceutical applications. - Describes the chemistry and applications of this important class of organometallic and coordination compounds - Includes contributions from global leaders in the field, featuring pioneers in the area as well as emerging experts conducting exciting research on pincer complexes - Highlights areas of promising and active research, including small molecule activation, earth abundant metals, and actinide chemistry