Reactions of a gaillum(II)-diazabutadiene dimer, [{{[(H)C(But)N]2}Gal}2],with [ME(SiMe3)2] (M = Li or Na;: E = N, P, or As):: Structural, EPR, and ENDOR characterization of paramagnetic Gallium(III) pnictide complexes

The reactions of the paramagnetic gallium(II) complex [{(Bu-t-DAB)GaI}(2) (Bu-t-DAB = {(Bu-t)NC(H)}(2)) with the alkali metal pnictides [ME(SiMe3)(2)] (M = Li or Na; E = N, P, or As) have been carried out under a range of stoichiometries. The 1:2 reactions have led to a series of paramagnetic gallium(III)-pnictide complexes, [(Bu-t-DAB)Ga{E(SiMe3)(2)}] (E = N, P,or As), while two of the 1:4 reactions afforded [(Bu-t-DAB)Ga{E(SiMe3)(2)}(2)] (E = P or As). In contrast, treatment of [{(Bu(t-)DAB)GaI}(2)] with 4 equiv of [NaN(SiMe3)(2)] resulted in a novel gallium heterocycle coupling reaction and the formation of the diradical species [(Bu-t-DAB)Ga[N(SiMe3)(2)}{[CC(H)N-2(Bu-t)(2)]-Ga[N(SiMe3)(2)]CH3}]. The mechanism of this unusual reaction has been explored, and evidence suggests it involves an intramolecular transmethylation reaction. The X-ray crystal structures of all prepared complexes are reported, and all have been characterized by EPR and ENDOR spectroscopies. The observed spin Hamiltonian parameters provide a detailed picture of the distribution of the unpaired spin density over the molecular frameworks of the complexes.