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

Abstract

The synthesis of a new potassium–indyl complex, K[In(NON^Ar)] (NON^Ar = [O(SiMe₂NAr)₂]²⁻, Ar = 2,6-ⁱPr₂C₆H₃) and its reactivity with organic azides RN₃ is reported. When R = 2,6-bis(diphenylmethyl)-4-^tBu-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, SiMe₃) generates tetrazenido-indium compounds K[In(NON^Ar){κ-N,N′-N₄(Mes)(R)-1,4}], shown by X-ray crystallography to contain planar InN₄ heterocycles in the anion.