Trimethylsilylcyclooctadiene-​transition metal complexes: metal-​catalyzed protodesilylation of cyclic vinylsilanes, and transfer hydrogenation promoted by the displaced silyl group

Complexes of 1-​trimethylsilyl-​1,​5-​cyclooctadiene (TMS-​COD) with AgI, RhI, PdII and PtII have been prepd. and characterized. The distortion in their structures in comparison with the near sym. structures of the corresponding, 1,​5-​cyclooctadiene (COD) complexes, which is obviously attributable to the presence of vinylic SiMe3 group, is clearly indicated by their 1H and 13C NMR spectral characteristics. The silver complex is somewhat unstable, but the other complexes are quite stable. An unstable CuI complex that could not be satisfactorily characterized was also obtained. If appropriate conditions for the prepn. of Rh and Pd complexes are not maintained, desilylation occurs, accompanied by redn. of COD to cyclooctene by transfer of hydrogen from the solvent alc. The displaced silicon-​contg. moiety seems to enhance the transfer hydrogenation. Attempts to prep. a RuII complex resulted in the formation of a complex of desilylated diene (RuII-​COD)​