The Effect of Hard and Soft Donors on Structural Motifs in (Isocyanide)gold(I) Complexes

摘要

Treatment of the (isocyanide)gold(I) species LAuCl with 4-mercaptoben-zoic acid in the presence of NaOMe yields the complexes [Au(4-SC_6H_4CO_2H)L] in good yield. Reaction of LAuCl with 2-HSQn (Qn = quinoline) and [Au(2-SPy)L], respectively. A structural investigation of the pyridylthiolato compound revealed chains of molecules with alternation medium and long Au-Au interactions Treatment of this compound with HBF_4 results in the cationic species [Au(2-HSPy)(2,6-Me_2C_6H_3NC)]~+ as the BF_4~- salt. The same product is obtained on reaction of [AuCl(2,6-Me_2C_6H_3NC)] with AgOTf followed by HSPy. Treatment of the gold(I) halide compounds LAuCl (L = ~tBuNC, 2,6-Me_2C_6H_3NC) with potassium 1,3,4-thiadiazole-2,5-dithiolate (KSSSK) leads to the isolation of dinuclear thiolatogold complexes [(AuL)_2(SSS)]. These products go on to form insoluble polymers through loss of isocyanide on standing in solution. A single crystal of [{Au(~tBuNC)]_2(SSS)] was obtained and the subsequent structural analysis revealed one of the most complicated networks known based solely on aurophilic interactions. A good comparison to the 'soft' S-donation of the thiolato ligands was provided by the synthesis of a number of nitratogold(I)complexes with the anion bound through the 'hard' O-donor. Reaction of ~iPrNC and CyNC with Au(tht)Cl provided the complexes [AuCl(~iPrNC)] and [AuCl(CyNC)], respectively. These compounds were found to yield the respective nitrato species [Au(NO_3)~iPrNC)] and [(Au(NO_3)(CyNC)] on treatment with AgNO_3. The nitrato complexes yielded single crystals enabling a structural investigation to be carried out. While [Au(NO_3)(CyNC)] has a more conventional structure with dimers aligned into strings with alternation short and long aurophilic bonding [Au(NO_3)(~iPrNC)] has a unique structure based on strings of alternating, corner-sharing Au_6 and Au_8 units with short Au-Au contacts in edge-sharing Au_3 triangles.