Silicon complexes with osmium

A second type of reactive metal-silicon bond involves multiple bonding, as might exist in a silylene complex, LnM=SiR2. The synthesis of isolable silylene complexes has led to the observation of new silicon-based reactivity patterns redistribution at silicon occurs via bi-molecular reactions of silylene complexes with osmium silylene complexes, reactions have been observed that mimic proposed transformations in the Direct Process. And, very recently, ruthenium silylene complexes have been reported to be catalytically active in hydrosilylation reactions. 

Silylene-metal complexes, with tricoordinate silicon, free of coordinating donors, have been difficult to synthesize. Only a few examples were known until recently one example is the osmium complex Cp (Me3P)2RuSi=Os(CO)4 synthesized by Tilley... 

The first silylene complexes of osmium porphyrin, (TTP)Os=SiR2-THF, were prepared by treating K2[Os(TTP)] with Cl2SiR2 or the reaction of [Os(TTP)]2 with hexamethylsilacyclopropane (116). The molecular structure of (TTP)Os=SiEt2-2THF is stabilized by coordination of THF to the silicon, as shown by X-ray crystallography (Fig. 5). The measured Os—Si distance of 2.325(8) A is the shortest ever reported (116). 

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