Syntheses, Structures, and Bonding Analyses of Carbene‐Stabilized Stibinidenes

Abstract

Reactions of two equivalents of LGa {L = HC[C(Me)NAr]2; Ar = 2,6‐iPr2‐C6H3} with SbX3 (X = Cl, Br) yield double‐inserted products (LGaX)2SbX (X = Cl 1, Br 2), which were isolated at –40 °C. Warming solutions of 1 and 2 to ambient temperature results in intramolecular elimination of LGaX2 and formation of Ga‐substituted stibinidenes L(X)GaSb as reaction intermediates, which were stabilized by coordination of strong σ‐donating carbenes. Four carbene‐stabilized stibinidenes MeCAAC‐SbGa(X)L {MeCAAC = [H2C(CMe2)2NAr]C, Ar = 2,6‐iPr2‐C6H3, X = Cl 3, Br 4} and IDipp‐SbGa(X)L {IDipp = 1,3‐bis(2,6‐diisopropylphenyl)‐imidazol‐2‐ylidene, X = Cl 5, Br 6} were characterized by single‐crystal X‐ray diffraction and the nature of the bonding in 3–6 was further investigated by quantum chemical methods. The studies reveal substantial Sb–Ccarbene π‐backbonding contributions in 3 and 4, whereas the IDipp‐stabilized derivatives 5 and 6 exhibit Sb–Ccarbene single bonds. DFT computations with and without dispersion corrections reveal that dispersion interactions mainly from the bulky aryl groups decisively contribute to the stability of 3–6.