Trinuclear pyridyl functionalised hydroxylaminato complexes of aluminium, gallium and indium

Abstract

The reaction of the donor functionalised N,N-bis[2-(pyrid-2-yl)ethyl]hydroxylamine [HON(C₂H₄-o-py)₂] and three equivalents of the Lewis-acids AlMe₃, GaMe₃ or InMe₃ resulted in the formation of dimethylhydroxylaminato–metal complexes of the general constitution [MMe₂ON(C₂H₄-o-py)₂·2MMe₃] with M = Al (1), Ga (2) or In (3) by methane elimination. An alternative method to generate complexes 1 and 2 is the transmetalation of [YCp₂ON(C₂H₄-o-py)₂] with an excess of AlMe₃ or GaMe₃, respectively. All compounds were characterised by elemental analysis, NMR spectroscopy and single-crystal X-ray diffraction. The complexes [GaMe₂ON(C₂H₄-o-py)₂·2GaMe₃] (2) and [InMe₂ON(C₂H₄-o-py)₂·2InMe₃] (3) show highly dynamic behaviour in solution with the two pyridine nitrogen atoms changing their coordination to the metal atoms rapidly at ambient temperature. VT ¹H NMR experiments showed that this dynamic exchange can be frozen on the NMR time scale. In contrast to 2 and 3, complex 1 does not change its coordination mode at ambient temperature in non-coordinating solvents.