Modification of Yttrium Silyl-Bridged Amide Alkyl Complexes through Si-H/C-H Cross-Dehydrocoupling of Silanes with a Silylamino Ligand: Synthesis, Reactivity, and Mechanism.

Abstract

A new method for the modification of a silylamino ligand has been developed through mono and dual C(sp3 )-H/Si-H cross-dehydrocoupling with silanes. The reaction of [LY{η2 -(C,N)-CH2 Si(Me2 )NSiMe3 }] (L=bis(2,6-diisopropylphenyl)-β-diketiminato, L' (1L '); L=tris(3,5-dimethylpyrazolyl)borate, TpMe2 (1TpMe2 )) with 2 equivalents of PhSiH3 in toluene gave the complexes [LY{η2 -(C,N)-C(SiH2 Ph)2 Si(Me2 )NSiMe3 }] (L=L' (2L' ); L=TpMe2 (2TpMe2 )). Moreover, 1TpMe2 reacted with the secondary silanes Ph2 SiH2 and Et2 SiH2 to afford the corresponding mono C-H activation products [TpMe2 Y{η2 -(C,N)-CH(SiHR2 )Si(Me2 )NSiMe3 }] (R=Ph (4 b); R=Et (4 c)). The equimolar reaction of 1TpMe2 with PhSiH3 also produced the mono C-H activation product 4 a ([TpMe2 Y{η2 -(C,N)-CH(SiH2 Ph)Si(Me2 )NSiMe3 }(thf)]). A study of their reactivity showed that4 a facilely reacted with 2 equivalents of benzothiazole by an unusual 1,1-addition of the C=N bond of the benzothiazolyl unit to the Si-H bond to give the C-H/Si-H cross-dehydrocoupling product [(TpMe2 )Y{η3 -(N,N,N)-N(SiMe3 )SiMe2 CH2 Si(Ph)(CSC6 H4 N)(CHSC6 H4 N)}] (5). These results indicate that this modification endows the silylamino ligand with novel reactivity.