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

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