ORGANOGOLD(III) METALLACYCLIC CHEMISTRY - PART 3 - SELF-ASSEMBLY OF THE NONAMETALLIC GOLD(III)-SILVER(I)-SULFIDO AGGREGATES [(LAU(MU-S)(2)AUL)(3)AG3X2](-DIMETHYLBENZYLAMINE LIGAND X = CL, BR), BY THIOUREA DESULFURIZATION() (L = CYCLOAURATED N,N)

Reaction of the gold(III) dihalide complexes [{C6H3(CH2NMe2)-2-R-5}AuX 2] (R = OMe, H; X = Cl, Br) with N,N'-dimethylthiourea and silver(I) o xide in refluxing dichloromethane gave the novel gold(III) aggregate c ations [{[{C6H3(CH2NMe2)-2-R-5}Au(mu-S)](2)}(3)Ag3X2](+), formed from the desulfurisation of the thiourea. The cations consist of three gold sulfide dimers doubly-bridged by three silver(I) cations, which in tu rn are triply-bridged by two halides. The aggregates have been fully c haracterised by H-1- and C-13-NMR spectroscopy and electrospray mass s pectrometry (ESMS), which showed very strong parent ions that proved r emarkably resilient to cone voltage induced fragmentation. Single crys tal X-ray structures have been determined for two examples, although t he nature of the counter-anion could not be unambiguously determined. The two X-ray studies show that both cis and trans isomers (with respe ct to the orientation of the N,N-dimethylbenzylamine ligands on either side of the Au2S2 group) form, although only one isomer was isolated in each case. To compare this chemistry with that of platinum(II), cis -[PtCl2(PPh3)(2)] and N,N'-dimethylthiourea were reacted in the presen ce of silver(I) oxide. Only the expected thiourea dianion complex [Pt{ SC(=NMe)NMe}(PPh3)(2)] formed, as observed in previously reported stud ies. The formation of the gold(III)-sulfido aggregates clearly demonst rates that gold(III) can have remarkably different chemistry to that o f platinum(II). Reaction of [{C6H3(CH2NMe2)-2-OMe-5}AuCl2] with N,N'-d iphenylselenourea in the presence of silver(I) oxide failed to give an alogous selenium aggregates. (C) 1998 Elsevier Science S.A. All rights reserved.