Reduction of organic azides by indyl-anions. Isolation and reactivity studies of indium–nitrogen multiple bonds

The synthesis of a new potassium–indyl complex, K[In(NON(Ar))] (NON(Ar) = [O(SiMe(2)NAr)(2)](2–), Ar = 2,6-(i)Pr(2)C(6)H(3)) and its reactivity with organic azides RN(3) is reported. When R = 2,6-bis(diphenylmethyl)-4-(t)Bu-phenyl, a dianionic alkyl-amide ligand is formed via C–H activation across a transient In–N(imide) bond. Reducing the size of the R-group to 2,4,6-trimethylphenyl (mesityl, Mes) enables oxidation of the indium and elimination of dinitrogen to afford the imide species, K[In(NON(Ar))(NMes)]. The anion contains a short In–N(imide) bond, shown computationally to contain appreciable multiple bond character. Reaction of isolated imides with an additional equivalent of azide (R = Mes, SiMe(3)) generates tetrazenido-indium compounds K[In(NON(Ar)){κ-N,N′-N(4)(Mes)(R)-1,4}], shown by X-ray crystallography to contain planar InN(4) heterocycles in the anion.