Synthesis of metallasiloxanes of group 13–15 and their application in catalysis

Abstract

Herein we report on the synthesis, characterization and catalytic application of metallasiloxanes of group 13–15. Reactions of R(Me)Si(OH)₂ (R = N(SiMe₃)-2,6-iPr₂C₆H₃) (A) with Bi(NEt₂)₃, Sb(NEt₂)₃, Ge[N(SiMe₃)₂]₂ and AlMe₃ afforded [R(Me)SiO₂BiNEt₂]₂ (1), [R(Me)SiO₂SbOSi(OH)(Me)R]₂ (2), [R(Me)SiO₂]₃(GeH)₂ (3), and [R(Me)SiO₂AlMe(THF)]₂ (4), respectively. Reactions of RSi(OH)₃ (B) with Bi(NEt₂)₃ and AlMe₃ produced complexes (RSiO₃Bi)₄ (5) and (RSiO₃)₂[AlMe(THF)]₃ (6). Compounds 1–6 have been characterized by IR and NMR spectroscopy, single crystal X-ray structure and elemental analysis. Each of the compounds 1, 2 and 4 features an eight-membered ring of composition Si₂O₄Bi₂, Si₂O₄Sb₂ and Si₂O₄Al₂, while 3 and 6 exhibit a bicyclic structure with the respective skeletons of Si₃O₆Ge₂ and Si₂O₆Al₃. Compound 5 has a cubic core of Si₄O₁₂Bi₄. Compounds 1–6 exhibit very good catalytic activity in the addition reaction of trimethylsilyl cyanide (TMSCN) with benzaldehyde. Compound 5 was found to be the best catalyst and its activity was probed in the reactions of TMSCN with a number of aldehydes and ketones.