The First Cyanomethyl Complex of Gold, Synthesized by Reaction of a AuI Complex with Acetonitrile in the Presence of a New Guanidine N-Superbase

Herein we report on the synthesis of the new strong N-base and electron donor tdmegb [1,2,4,5-tetrakis(N,N'-dimethylethyleneguanidino)benzene]. Compared to the previously synthesized ttmgb [1,2,4,5-tetrakis(tetramethylguanidino)-benzene], this compound turned out to be a slightly better electron donor and a slightly weaker base. In experiments in which [AuCl(PPH3)] was dissolved in CH3CN together with tdmegb, we observed the formation of the first cyanomethyl complex of Au, namely [Au(CH2CN)(PPh3)] in good yield. This reaction does not take place for ttmgb. Moreover, in CH2Cl2 solutions containing the three components [AuCl(PPh3)], tdmegb and a nitrite (in large excess), only Au-I reduction leading to a [Au11Cl3(PPh3)(7)] cluster is observed. Possible reaction mechanisms for this unusual reaction are discussed.