Silane ligand bridging

A subsequent DFT study has confirmed the new mechanism of olefin hydrosilylation but found that catalytically active complex has a nonclassical rf-bonded silane ligand, that is, Ru—Si bond is bridged by two hydrogen atoms (Fig. 5). 

In a similar manner, dimethyl-bis(phenylethynyl)silane forms a derivative in which both acetylenic groups act as bridging ligands (79, 80) ... 

The first complex with a metal-metal bond that is bridged by only a single silylene ligand has been prepared in a low yield by treatment of chloro(hydro)silane with base in the presence of Fe2(CO)9 [Eq. (33)].65 However, this product is reported to be inflammable in air and stable only at low temperature. 

A silyl-bridged bis(allyl)ligand made from the bis(allyl) silane Me2Si(CH2CHCHSiMe3)2 can be converted into its dilithium or dipotassium salt (i.e. K2[3-(C3H3SiMe3-l)2SiMe2]) (equation 1) it has been used in the synthesis of ans a-bis(allyl) complexes. ... 

Cyclohexane formation is entropically less favorable than cyclopentane generation, and treatment of 1,6-dienes under the conditions listed in Eq. (47) leads to the production of uncyclized, disilylated products (Eq.49) [35] or silicon bridged dimers [40]. To avoid these problems, phenylmethylsilane can be employed as the chain terminator. Utilizing this more hindered silane slows the o-bond metathesis sufficiently to prevent dimerization (Eq. 50). The trapping step can be retarded even further by the use of diphenylsilane (Eq. 51). Thus, not only can the metal and the ligand array be manipulated to bring about the desired result in the catalytic process, but the properties of the silane reagent itself can also be adjusted to meet the demands of the synthesis at hand. 

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