Silyl-transition-metal complexes

Table 3. SiM distances (A) in silyl-transition-metal complexes obtained by X-ray diffraction studies...

A major problem in postulating silylenoid metal complexes as intermediates in the redistribution reactions is simply that good model compounds are lacking, and the decomposition mechanisms of silyl transition metal complexes have not been systematically investigated. While there is evidence for transient R2Si species produced by thermal or photochemical means (80-83), there are no known monomeric silylene metal complexes. Several monomeric stannylene and germylene complexes are... 

The mechanism and stereochemistry of reactions with transition metals. In connection with the mechanism of hydrosilylation reactions, it is of interest to discuss the stereochemistry of silyl-transition metal complexes (12) and the stereochemical aspects of the reactions of silicon hydrides with transition metals. 

The chemistry of organosilicon compounds has expanded with the use of transition metals. Both catalytic processes (179) and the chemistry of silicon transition metal compounds (180) have been developed. Catalytic reactions of organosilanes and more recently, reactions of silyl-transition metal complexes have already found interesting applications in organic synthesis (80,181,182). 

Chiral organosilanes have been shown to undergo stereospecific catalytic reactions leading to the preparation of optically active silyl-transition metal complexes. We first discuss the stereochemistry and mechanism of transition metal catalyzed reactions of organosilicon compounds. Then the stereochemistry of chiral organosilyl-transition metal complexes are described. The chemistry of optically active silyl- and germyl-transition metals has been the subject of a recent review (12), and we concentrate here on mechanistic implications, especially in the field of homogeneous catalytic reactions. 

Stereochemical studies have brought new insights into catalytic reactions of organosilicon compounds. An approach to the mechanism of transition metal reactions has been made in the study of the stereochemistry of silyl-transition metal complexes. We review here the known chemistry of optically active com-... 

C. Chiral Silyl-Transition Metal Complexes Nucleophilic Displacement of... 

Numerous silyl-transition metal complexes have been obtained and studied56,57, owing to the many stereospecific substitution reactions which can be performed at the silicon atom. 

Interestingly, a new factor determining the predominant stereochemistry at silicon has recently been pointed out77. The LiAlH4 cleavage of hexacoordinated silyl-transition metal complexes was shown to proceed with predominant retention at silicon, regardless of the nature of the ligands around the metal atom (Table 32). The stereoselectivity was... 

Me,-CcTaCl,(11 -COSiMe,) results, pyridine then giving a zwitterionic adduct in which the pyridine is replacable by phosphines. A series of mixed silyl-transition metal complexes Sif-I-M have been made, C H Mn(C0)2 and Me SiX give CjH Kn(C0)2SiMe2, while deprotonation of cis-Cp(C0) Re( iPh )H occurs at followed by silyl migration to the ring."" ... 

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