Lewis base properties of tris(trimethylstannyl)amine: unusually short M–N bonds of the adduct compounds [X3M·N(SnMe3)3] (X = Cl, Br; M = Al, Ga, In) and [Cl2(CH3)M·N(SnMe3)3] (M = Al, Ga)

Abstract

The Lewis acid/base adducts [X₃M·N(SnMe₃)₃] (1a: M = Al, X = Cl; 2a: M = Ga, X = Cl; 2b: M = Ga, X = Br; 3a: M = In, X = Cl; 3b: M = In, X = Br) and [Cl₂MeM·N(SnMe₃)₃] (1b: M = Al, 2c: M = Ga) were prepared by the 1 ∶ 1 mole reaction of MX₃ and MCl₂Me with N(SnMe₃)₃ at room temperature in diethyl ether and crystallised from dichloromethane at −20 °C. The new compounds were fully characterised by elemental analysis, NMR spectroscopy and single crystal X-ray diffraction. Unusually short M–N bond lengths of 1.87(1) Å for Al–N (1a), 1.950(7) Å for Ga–N (2a) and 2.148(6) Å for In–N (3a) were found indicating very strong donor–acceptor bonds.