Platinum methyl complexes

A,iV-diaryl-l,4-diaza-l,3-butadienes also form stable dimethyl- and chloro(methyl)-platinum complexes 16 and 17. Addition of the ligand to Pt2Me4(/i-SMe2)2 and PtMe2(cod) yields the dimethylplatinum(ii) complexes having chelating diimines. 

A series of chloro(methyl)platinum complexes having 2,9-dimethyl-l,10- phenanthroline are obtained as the adducts of alkenes, allene, and GO (23-27, Scheme Not only does coordination of the unsaturated molecule... 

Ferrocene-containing N,P- and P,A-chelating ligands are employed for preparation of chloro(methyl)platinum complexes 34 and 35. ... 

A methylplatinum complex with a siloxo ligand has been prepared by the metathesis reaction of a chloro(methyl)-platinum complexes with Na[SiOPh3]/ A dinuclear Pt complex with bis(trimethylsilyl)methyl ligands and bridging chloro ligands 52 reacts with /-butyl isocyanide and then with NaCp to produce the platina(amino)fulvene 53 via addition of Cp to the coordinated isonitrile and migration of the hydrogen atom (Equation (15))/ ... 

The chloro(methyl)platinum complex 87, with a chelating 1,2-diphosphine ligand, undergoes insertion of SO2 into the Pt-C bond to form the methyl sulfonyl complex 88 (Equation (18))7 ... 

The corresponding complexes with iV-coordinated acrylonitrile or 7r-coordinated ethylene 120 and 121 are prepared from the reactions of AgBp4 with a chloro(methyl)platinum complex in the presence of the olefins, respectively (Scheme... 

The chloro(methyl)platinum complex with dppe as a ligand reacts with Ph3P=C=C=0 in the presence of AgBp4 to form the cationic complex with the ketenyl ligand, 144 (Scheme Addition of alcohol to the C=C double... 

PFg, a rather than tt interactions are thought to be dominant in the phenyl platinum bond. The question of the NMR trans influence is considered in several papers involving methyl platinum complexes 241] with the evidence interpreted in a way which supports the a-re-... 

Figure 3.115 (a) Syntheses of organoplatinum phosphine complexes (b) structures of methyl-platinum phosphine complexes. 

Styrene, a-ethyl-asymmetric hydroformylation catalysts, platinum complexes, 6, 266 asymmetric hydrogenation catalysts, rhodium complexes, 6, 250 Styrene, a-methyl-asymmetric carbonylation catalysis by palladium complexes, 6, 293 carbonylation... 

Molecules having only a sulfoxide function and no other acidic or basic site have been resolved through the intermediacy of metal complex formation. In 1934 Backer and Keuning resolved the cobalt complex of sulfoxide 5 using d-camphorsulfonic acid. More recently Cope and Caress applied the same technique to the resolution of ethyl p-tolyl sulfoxide (6). Sulfoxide 6 and optically active 1-phenylethylamine were used to form diastereomeric complexes i.e., (-1-)- and ( —)-trans-dichloro(ethyl p-tolyl sulfoxide) (1-phenylethylamine) platinum(II). Both enantiomers of 6 were obtained in optically pure form. Diastereomeric platinum complexes formed from racemic methyl phenyl (and three para-substituted phenyl) sulfoxides and d-N, N-dimethyl phenylglycine have been separated chromatographically on an analytical column L A nonaromatic example, cyclohexyl methyl sulfoxide, did not resolve. 

The hexakis(methyl isocyanide) dimers, [Pt2(CNMe)6], undergo photolytic cleavage of the Pt—Pt bond to give 15-electron radicals, Pt(CNMe)3.94 Mixtures of platinum and palladium dimers give rise to heteronuclear complexes under photolytic conditions. Mixtures of normal and deuterium-labeled methyl isocyanide complexes reveal that the metal-ligand bonds undergo thermal redistribution.94... 

The proposed mechanism starts with a methyl group abstraction on platinum complex 416 with the borane reagent in the presence of diyne 414 (Scheme 105). The square-planar cationic diyne-platinum(n) complex 417 is converted to the octahedral platinum(rv) hydride intermediate 418 through oxidative addition of the hydrosilane. This complex decomposes rapidly with methane release to form another tetracoordinated platinum(n) species 419, followed by platinasilylation of the triple bond. The resulting vinylplatinum 420 undergoes an intramolecular carboplatination to... 

The question of which pathway is preferred was very recently addressed for several diimine-chelated platinum complexes (93). It was convincingly shown for dimethyl complexes chelated by a variety of diimines that the metal is the kinetic site of protonation. In the system under investigation, acetonitrile was used as the trapping ligand L (see Fig. 1) which reacted with the methane complex B to form the elimination product C and also reacted with the five-coordinate alkyl hydride species D to form the stable six-coordinate complex E (93). An increase in the concentration of acetonitrile led to increased yields of the methyl (hydrido)platinum(IV) complex E relative to the platinum(II) product C. It was concluded that the equilibration between the species D and B and the irreversible and associative1 reactions of these species with acetonitrile occur at comparable rates such that the kinetic product of the protonation is more efficiently trapped at higher acetonitrile concentrations. Thus, in these systems protonation occurs preferentially at platinum and, by the principle of microscopic reversibility, this indicates that C-H activation with these systems occurs preferentially via oxidative addition (93). 

Section III.C A Hydrido(methyl)carbene Complex of Platinum(IV) (223) and Methyl(hydrido)platinum(IV) Complexes with Flexible Tridentate Nitrogen-Donor Ligands (224) are structurally related to the system shown in Scheme 13 and give additional information on how steric and electronic factors influence the stability of platinum(IV) methyl hydrides. 

Insertion and migration refer to the process in which an unsaturated molecule inserts to a metal-anion bond. The two ways of describing this elementary step have been depicted in Figure 2.2 and 2.3 In the platinum complex shown an acetyl fragment is formed from a co-ordinated CO and a methyl group, both attached to platinum. Clearly, the two reacting groups should occupy positions cis to one another, otherwise the reaction cannot occur [1]. 

Williams group observed low enantioselectivities for the Michael addition of a prochiral nucleophile, ethyl 2-cyanopropionate 623, to methyl vinyl ketone 624 catalyzed by chiral platinum complexes (Scheme 8.196)." The NMR analysis indicated that these cationic Pt complexes act as Lewis acids toward nitriles. The X-ray crystal structure as well NMR analysis showed that the solvent ligand that is readily displaced by an organic substrate is situated cis to the nitrogen donor in the Pt complex and, therefore, is in a chiral pocket created by the oxazoline ring. 

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