Distinctly different reactivity of bis(silylenyl)-versus phosphanyl-silylenyl-substituted o-dicarborane towards O2, N2O and CO2

Abstract

In stark contrast to the reactivity of the bis-silylenyl dicarborane CB–Si₂ (1) [CB = ortho-C,C′-C₂B₁₀H₁₀, Si = PhC(tBuN)₂Si] towards O₂, N₂O, and CO₂, yielding the same dioxygenation product CB–Si₂O₂ (2) with a four-membered 1,3,2,4-disiladioxetane ring, the activation of the latter small molecules with the phosphanyl-silylenyl-functionalised CB–SiP (3) {PP[N(tBu)CH₂]₂} affords with O₂ the CB–Si(O)P(O) silanone-phosphine oxide (4), with N₂O the CB–Si(O)P silanone-phosphine (5), and with CO₂ the CB–Si(O₂CO)P silicon carbonate-phosphine (6) and CB–C(O)OSiOP ester (7), respectively.