The effect of hard and soft donors on structural motifs in (isocyanide)gold(I) complexes

Treatment of the (isocyanide)gold(I) species LAuCl (L = 'BuNC.2.6-Me2C6H3NC ) with 4-mercaptobnzoic acid in the presence of NaOMe yields the complexes [Au(4-SC6H4CO2H)L] in good yield. Reaction of LAuCl with 2-HSQn (Qn = quino line) and 2-HSPy (Py = pyridine) under the same conditions provides the thi olato compounds [Au(2-SQn)L] and [Au(2-SPy)L], respectively. A structural i nvestigation of the pyridylthiolato compound revealed chains of molecules w ith alternating medium and long Au-Au interactions Treatment of this compou nd with HBF4 results in the cationic species [Au(2-HSPy)(2.6-Me2C6H3NC)], a s the BF4- salt. The same product is obtained on reaction of [AuCl(2,6-Me2C 6H3NC)] with AgOTf followed by HSPy. Treatment of the gold(!) halide compou nds LAuCl (L = 'BuNC, 2,6-Me2C6H3NC) with potassium 1.3,4-thiadiazole-2.5-d ithiolate (KSSSK) leads to the isolation of dinuclear thiolatogold complexe s [(AuL)2(SSS)]. These products go on to form insoluble polymers through lo ss of isocyanide on standing in solution. A single crystal of [{Au('BuNC)(2 )(SSS)] was obtained and the subsequent structural analysis revealed one of the most complicated networks known based solely on aurophilic interaction s. A good comparison to the 'Soft' S-donation of the thiolato ligands was p rovided by the synthesis of a number of nitratogold(I)complexes with the an ion bound through the 'hard' O-donor. Reaction of 'PrNC and CyNC with Au(th t)Cl provided the complexes [AuCl((PrNC)-Pr-i)] and [AuCl(cyNC)], respectiv ely. These compounds were found to yield the respective nitrato species [Au (NO3)(PrNC)-Pr-1)] and [(Au(NO3)(CyNC)] on treatment with AgNO3 The nitrato complexes yielded single crystals enabling a structural investigation to b e carried out. While [Au(NO3)(CyNC)] has a more conventional structure with dimers aligned into strings with alternating short and long aurophilic bon ding. [Au(NO3)((PrNC)-Pr-i)] has a unique structure based on strings of alt ernating, corner-sharing Au-0 and Au-8 units with short Au-Au contacts in e dge-sharing Au-3 triangles.