The reactivity of diazabutadienes toward low oxidation state Group 13 iodides and the synthesis of a new gallium(i) carbene analogue

The reactions of two diazabutadiene ligands, Ar-DAB [(ArN=CH)₂, Ar = 2,6-Prⁱ₂C₆H₃] and Bu^t-DAB [(Bu^tN=CH)₂] with either GaI or an AlI₃/Al mixture have afforded the paramagnetic compounds, [{IGa^II(Bu^t-DAB)}₂], [I₂Ga^III- (Bu^t-DAB)] and [I₂Al^III(Ar-DAB)] which have been characterised by X-ray crystallography and EPR spectroscopy. In addition, the diamagnetic, ionic complex, [I₂Al^III(Ar-DAB)]I, has been prepared and structurally characterised. The reduction of [I₂Ga^III(Ar-DAB)] with potassium metal in the presence of various Lewis bases has led to (three structurally characterised compounds, [{(Et₂O)KGa^I(Ar-DAB)}₂], [{(TMEDA)KGa^I(Ar-DAB)}₂] and [:Ga^I(Ar-DAB)]₂[{K(18-crown-6)}₂(μ-18- crown-6)], which contain the second example of an anionic gallium(I) carbene analogue. In addition, the former two compounds display Ga · · · Ga interactions in the solid state which are unprecedented for this complex type.