Cobalt silyl complexes optical activity

Silicon and germanium hydrides react with cobalt, manganese and rhenium carbonyls affording complexes having a silicon (or germanium)-metal bond. These reactions, described previously for inactive compounds have been used in the synthesis of optically active silyl and germyl-transition metals ... 

The chemistry of silicon, germanium, and tin transition metal compounds has been the subject of several reviews (12, 180). Optically active silyl ligands have been introduced in a transition metal complex by reaction of chiral functional organosilanes. However chiral silyl ligands containing complexes are limited to a few metal centers we shall discuss in turn iron, cobalt, platinum, and manganese complexes. 

The reaction of metal carbonyl dimers with silicon hydrides also probably involves an initial oxidative addition step. Chiral silyl-cobalt and silyl-manganese carbonyl complexes have been obtained through the reaction of optically active organosilicon hydrides with metal carbonyls65 68 (equation 15 and 16). Phosphine-substituted cobalt complexes were similarly obtained by reaction of a chiral hydrosilane with Co2(CO)6L2 [L = PPh3, P(OPh)3, P(c-C6Hn)3]69. 

The formation of chiral silyllithium and silyl-Grignard reagents was also observed in the reactions of an optically active silyl-cobalt carbonyl complex93,94. Treatment of the chiral cobalt complex with methyllithium produced optically active silyllithium which hydrolysed to the corresponding hydrosilane (equation 26). 

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