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(NONAr)] (NONAr = [O(SiMe2NAr)(2)](2-), Ar = 2,6-(Pr2C6H3)-Pr-i) and its reactivity with organic azides RN3 is reported. When R = 2,6-bis(diphenylmethyl)-4-Bu-t-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(NONAr)(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, SiMe3) generates tetrazenido-indium compounds K[In(NONAr){kappa-N,N'-N-4(Mes)(R)-1,4}], shown by X-ray crystallography to contain planar InN4 heterocycles in the anion.