Reactions of Low-Valent Gallium Species with Organic Azides: Formation of Imido-, Azoimido-, and Tetrazene Complexes.

The reactivity of two α-diimine-ligated digallanes, [LGa-GaL] (L = [(2,6-iPrCH)NC(CH)], dpp-dad, ; L = 1,2-[(2,6-iPrCH)NC]CH, dpp-bian, ), and a gallylene, [(L)GaNa(THF)] (), toward organic azides was studied. Reaction of digallane or with trimethylsilyl azide (MeSiN), 2-azido-benzonitrile (2-CNCHN), or tosylazide (TosN) results in imido-bridged complexes, [(L)Ga(μ-NSiMe)Ga(L)] () [(L)Ga(μ-NSiMe)Ga(L)] (), [(L)Ga(μ-2-CNCHN)Ga(L)] (), and [(L)Ga(μ-NTos)Ga(L)] (), with elimination of dinitrogen. Treatment of or with 1-adamantyl azide (1-AdN), on the other hand, affords the unsymmetrical dinuclear complexes [(L)Ga(NAd)(NAd)Ga(L)] () and [(L)Ga(NAd)(NAd)Ga(L)] (), which contain both imido and triazene bridges. Different from the Ga(II) complexes and , the reactions of Ga(I) species with benzylazide or trimethylsilyl azide result in the tetrazene complex {Na(THF)}[(L)Ga(benzyl-N-benzyl)] () and amide complex {Na(THF)}[(L)Ga(NHSiMe)(benzyl)] (). It is likely that these latter transformations proceed via the transient formation of the corresponding Ga═N imide complex, which undergoes either cycloaddition with a second azide (to form ) or activation of the C-H bond of methyl in one solvent toluene molecule (to yield ).