The effect of trimethylsilyl substituents on the ring-slippage of bis-indenyl-molybdenocene derivatives

A group of new trimethylsilyl indenyl derivatives of molybdenum is reported, starting from the allyl compound TMSIndMo(η3-C3H5)(CO)2 [TMSInd=η3-SiMe3C9H6]. The novel allyl Mo(II) complex, which is synthesized by the reaction of Mo(η3-C3H5)(CO)2(NCMe)2Cl with Li(TMSInd) in THF, is the precursor to trimethylsilyl indenyl derivatives. Treatment of TMSIndMo(η3-C3H5)(CO)2 with HCl and addition of LiInd or LiTMSInd gives the ring-slipped complexes (η5-TMSInd)Mo(η3-Ind)(CO)2 or (η5-TMSInd)Mo(η3-TMSInd)(CO)2 in high yield. The presence of the trimethylsilyl substituent changes substantially the flexibility of the indenyl groups. These new substituted indenyl complexes were characterized by experimental techniques and ab initio calculations, and examined by cyclic voltammetry.