Sigma-Bond Metathesis Reactions Involving Lanthanide-Silicon and Lanthanide-Hydrogen Bonds

Abstract Neutral lanthanide silyl complexes Cp∗2LnSiH(SiMe3)2 (1, Ln=Sm; 2, Ln=Nd; 3, Ln=Y; Cp∗=η5-C5Me5) are synthesized by reaction of the corresponding alkyls Cp∗2LnCH(SiMe3)2 with neat SiH2(SiMe3)2. These complexes are monomeric in solution, but form dimers in the solid state through intermolecular LnηCH3-Si interactions. Mechanistic studies on this reaction indicate that it proceeds via a second-order autocatalytic process catalyzed by [Cp∗2LnH]2. Reactions of [Cp∗2LnH]2 with Cp2WH2 give the σ-bond metathesis products Cp∗2Ln(μ−η1,η5-C5H4)(μ-H)2WCp (5, Ln=Sm; 6, Ln=Y), via activation of a C-H (and not a W-H) bond of the tungsten hydride. The lanthanide borohydride complexes Cp∗2Ln(η2-H2BMes2) (Mes=mesityl; 7, Ln=Sm; 8, Ln=Y) are obtained by the reaction of [Cp∗2LnH]2 with [HBMes2]2. Key Words: Autocatalysisborohydridehydridelanthanide complexessilyltungsten.