Phosphine complexes of platinum and palladium

Tertiary phosphine complexes of platinum and palladium M(PR3)2X2 are important [95]. The cis- and trans- somers are readily obtained for platinum,... 

The effect of having bulky groups (e.g., /-butyl) in the phosphine ligand of platinum and palladium complexes has been studied in some detail by Shaw and his co-workers (9-12, 30, 31, 88). They have used a number of phosphines containing aromatic groups, e.g., di-/-butylphen-ylphosphine intramolecular ring closure occurs with the elimination of HC1 (9, 10), e.g.,... 

C,P-Coordination is also observed in a series of bi- and trinuclear diphenyldi-phosphine complexes containing platinum and palladium [698a], Some representatives of complexes with C,Te-coordinated ligands have also been described [634]. 

The coordinative reactivity of phosphine complexes of platinum(O), palladium(O) and nickel(O) Reversible activation of covalent molecules by transition metal complexes. The role of the covalent molecule... 

Orpen, A.G., Pringle, P.G., Smith, M.B., and Worboys, K., Synthesis and properties of new tris(cyanoethyl)phosphine complexes of platinum(0,II), palladium, II), iridium(I) and rhodium(I). Conformational analysis of tris(cyanoethyl)phosphine ligands,. Organomet. Chem., 550, 255, 1998. 

E5.4 Formation of platinum and palladium clusters with carbonyl and phosphine ligands E5.5 Reactivity and flexibility in platinum metal clusters E5.6 Excited state properties of the low-valent bi- and trinuclear complexes of palladium and platinum E5.7 Interstitial nickel carbonyl clusters... 

Phosphine complexes of platinum, palladium, and nickel also react in a similar manner ... 

A proposed mechanism [9] for the hydrosilylation of olefins catalyzed by platinum(II) complexes (chloroplatinic acid is thought to be reduced to a plati-num(II) species in the early stages of the catalytic reaction) is similar to that for the rhodium(I) complex-catalyzed hydrogenation of olefins, which was advanced mostly by Wilkinson and his co-workers [10]. Besides the Speier s catalyst, it has been shown that tertiary phosphine complexes of nickel [11], palladium [12], platinum [13], and rhodium [14] are also effective as catalysts, and homogeneous catalysis by these Group VIII transition metal complexes is our present concern. In addition, as we will see later, hydrosilanes with chlorine, alkyl or aryl substituents on silicon show their characteristic reactivities in the metal complex-catalyzed hydrosilylation. Therefore, it seems appropriate to summarize here briefly recent advances in elucidation of the catalysis by metal complexes, including activation of silicon-hydrogen bonds. 

Asymmetric hydrosilylation of prochiral olefins, e.g. 1,1-disubstituted olefins, catalyzed by chiral phosphine complexes of platinum(II) [21], nickel(II) [22], and palladium(II) [23] has been reported. When a platinum complex of the type [L PtCl2]2, where L stands for (/ )-benzylmethylphenylphosphine (BMPP), was used as catalyst, methyldichlorosilane, but not trichlorosilane, reacted satisfactorily- with a-methylstyrene, 2,3-dimethyl-l-butene, and 2-methyl-l-butene to give the corresponding optically active addition products, RMeC HCH2SiMeCl2, R = Ph, /-Pr,... 

Biphenylene underwent dimerization in the presence of phosphine complexes of Group 10 transition metals to afford tetraphenylene (2) [4]. Catalytic hydrogenation of biphenylene with phosphine complexes of rhodium, nickel, palladium, and platinum resulted in the formation of biphenyl (3) [5]. Hydrosilylation and hydroboratlon of biphenylene occurred in the presence of a palladium catalyst to give 2-silylbiphenyls and 2-borylbiphenyl 4, respectively [6]. Disilanes, a... 

Ethylene (tert-phosphine) complexes of zero-valent nickeP and platinum have been known for years. Analogous palladium complexes can be synthesized along the same lines as those reported for the nickel compounds, using ethoxy-diethylaluminum(III) as the reducing agent in the presence of ethylene. These palladium-ethylene complexes may serve as starting materials for oxidative addition reactions, since the ethylene ligand is loosely bonded. ... 

It has been shown that electron-rich cyclopropanes are able to displace ethylene from dichloro(ethylene)platinum to yield four-membered metallocyclic complexes (cf. equation 37). On the other hand 1,1,2,2-tetracyanocyclopropane (171) reacts under mild conditions with zerovalent platinum and palladium complexes of the type Pt(PPh3)2 (C2H4) or ML (n = 3, 4 M = Pd or Pt L = phosphines or triphenylarsines) to give metallocyclobutane derivatives (172) (equation 118) . 

The asymmetric hydrosilylation of a-methylstyrene with methyldi-chlorosilane has been catalyzed by (/ )-benzylmethylphenylphosphine complexes of platinum(II) 302) or nickel(II) 304) to give a 5 or 17.6% excess of one enantiomer in the addition product, 2-phenylpropyl-methyldichlorosilane. The corresponding palladium(II) complexes were, however, only slightly useful for asymmetric synthesis in hydrosilylation of olefins. Nevertheless, palladium(II) complexes of methyldiphenyl-phosphine or epimeric neomethyldiphenylphosphine, where the dissymmetry is remote from the phosphorus, are especially useful for the induction of asymmetry in the hydrosilylation of styrene and some cyclic conjugated dienes 199). A similar procedure has been used for... 

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