AMINE ADDITIONS TO MU-(1,2-DIISOCYANOBENZENE)-BIS(CHLOROGOLD) - REACTIVITY OF NEIGHBORING ISOCYANO FUNCTION AND [AU]C TRANSFER

mu-(1,2-Diisocyanobenzene)bis(chlorogold) (2) reacts with 1,2-diaminobenzene (1/1) to give benzimidazolin-2-ylidene(chloro)gold (3) as the only reaction product, while 1/1-mixtures of 3 and the corresponding diaminocarbene complexes (4, 6) result from the reactions of 2 with 1,8-diaminonaphthalene or two equivalents of aniline. With one equivalent of a primary amine (MeNH2, PhNH2), however, the isocyanide complexes Au(Cl)CNR (R = Me, Ph) are obtained, again together with 3. Mechanistic key steps following the primary nucleophilic attack by the amine are a novel NC-coupling of the two neighbouring isocyano functions to give a benzimidazole ring system, and the transfer of the exocyclic Au(Cl)C fragment onto the incoming amine. Accordingly, the reactions between 2 and secondary amines lead to an isolable binuclear intermediate C' (1/1) or to the carbene complexes Au(Cl){C(NR2)2} (8, 2R = (CH2)5; 9, 2R = (CH2)2O(CH2)2; 10, R = Me; 11, 2R = (CH2)4) (1/2), respectively. 7 and morpholine give 3 and the asymmetrical diaminocarbene complex Au(Cl){C[ activated N(CH2)4CH2]-[ activated N(CH2)2OCH2CH2]} (12).