Selective Si-C(sp 3 ) bond cleavage of a silyl-bridged amido alkyl ligand in an yttrium complex.

Compared with Si-C(sp 2 and sp) bonds bearing neighboring π-bond hyperconjugative interactions, the activation of robust Si-C(sp 3 ) bonds has proved to be a challenge. Herein, two distinct Si-C(sp 3 ) bond cleavages have been realized by rare-earth-mediated and nucleophilic addition of unsaturated substrates. The reactions of Tp Me2 Y[κ 2 -(C,N)-CH(SiH 2 Ph)SiMe 2 NSiMe 3 ](THF) (1) with CO or CS 2 gave two endocyclic Si-C bond cleavage products, Tp Me2 Y[κ 2 -(O,N)-OCCH(SiH 2 Ph)SiMe 2 NSiMe 3 ](THF) (2) and Tp Me2 Y[κ 2 -(S,N)-SSiMe 2 NSiMe 3 ](THF) (3), respectively. However, 1 reacted with nitriles such as PhCN and p -R'C 6 H 4 CH 2 CN in a 1 : 1 molar ratio to yield the exocyclic Si-C bond products Tp Me2 Y[κ 2 -(N,N)-N(SiH 2 Ph)C(R)CHSiMe 2 NSiMe 3 ](THF) (R = Ph (4); R = C 6 H 5 CH 2 (6H); R = p -F-C 6 H 4 CH 2 (6F); and R = p -MeO-C 6 H 4 CH 2 (6MeO)), respectively. Moreover, complex 4 can continuously react with an excess of PhCN to form a Tp Me2 -supported yttrium complex with a novel pendant silylamido-substituted β-diketiminato ligand, Tp Me2 Y[κ 3 -(N,N,N)-N(SiH 2 Ph)C(Ph)CHC(Ph)N-SiMe 2 NSiMe 3 ](PhCN) (5).