Trinuclear pyridyl functionalised hydroxylaminato complexes of aluminium, gallium and indium.

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 x 2 MMe3] 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 x 2 GaMe3] (2) and [InMe2ON(C2H4-o-py)2 x 2 InMe3] (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.