Gold(I) Heteroatom-Substituted Imido Complexes. Amino Nitrene Loss from [(LAu)₃(μ-NNR₂)]⁺

The heteroatom-substituted imido complexes [(LAu)3(μ-NX)]+ (X = NR2, R = Ph, Me, Bz; X = OH, Cl; L = a phosphine) have been prepared from the reactions of NH2X with [(LAu)3(μ-O)]+. Thermally unstable [(LAu)3(μ-NNMe2)]+ (L = P(p-XC6H4)3, X = H, F, Me, Cl, MeO) decompose to the gold cluster [LAu]62+ and tetramethyltetrazene Me2NNNNMe2. The decomposition is first-order overall with a rate constant that increases with increasing pKa of the phosphine ligand. Activation parameters for the decomposition are ΔH⧧ = 99(4) kJ/mol and ΔS⧧ = 18.5(5) J/K·mol for L = PPh3 and ΔH⧧ = 78(3) kJ/mol and ΔS⧧ = −47(2) J/K·mol for L = P(p-MeOC6H4)3. The decomposition of analogous [(LAu)3(μ-NNBz2)]+ produces bibenzyl, indicative of the release of free amino nitrene Bz2NN.