Selective Si-C(sp3) bond cleavage of a silyl-bridged amido alkyl ligand in an yttrium complex.

Abstract

Compared with Si-C(sp2 and sp) bonds bearing neighboring π-bond hyperconjugative interactions, the activation of robust Si-C(sp3) bonds has proved to be a challenge. Herein, two distinct Si-C(sp3) bond cleavages have been realized by rare-earth-mediated and nucleophilic addition of unsaturated substrates. The reactions of TpMe2Y[κ2-(C,N)-CH(SiH2Ph)SiMe2NSiMe3](THF) (1) with CO or CS2 gave two endocyclic Si-C bond cleavage products, TpMe2Y[κ2-(O,N)-OCCH(SiH2Ph)SiMe2NSiMe3](THF) (2) and TpMe2Y[κ2-(S,N)-SSiMe2NSiMe3](THF) (3), respectively. However, 1 reacted with nitriles such as PhCN and p-R'C6H4CH2CN in a 1 : 1 molar ratio to yield the exocyclic Si-C bond products TpMe2Y[κ2-(N,N)-N(SiH2Ph)C(R)CHSiMe2NSiMe3](THF) (R = Ph (4); R = C6H5CH2 (6H); R = p-F-C6H4CH2 (6F); and R = p-MeO-C6H4CH2 (6MeO)), respectively. Moreover, complex 4 can continuously react with an excess of PhCN to form a TpMe2-supported yttrium complex with a novel pendant silylamido-substituted β-diketiminato ligand, TpMe2Y[κ3-(N,N,N)-N(SiH2Ph)C(Ph)CHC(Ph)N-SiMe2NSiMe3](PhCN) (5).