Mesityl gold(III) complexes. X-ray structure of mononuclear [Au(mes)2Cl(PPh3)] and the dimer [Au(mes)2Cl]2

The reaction between PPN[AuCl4] and [Hg(mes)2] gives the anionic complex cis-PPN[Au(mes)2Cl2] (1) and [Hg(mes)Cl] as side-product. Complex 1 is a precursor to other compounds both neutral and cationic. Removal of one chloride ligand affords the mononuclear neutral complexes cis-[Au(mes)2ClL] (L=PPh3 (2), P{p-tol}3 (3), AsPh3 (4), SPPh3 (5)) by addition of a neutral ligand or, alternatively if no ligand is added, dimeric cis-[Au(mes)2Cl]2 (6). If both chloride groups in 1 are removed, cationic compounds can be obtained by addition of a potentially bidentate ligand affording cis-[Au(mes)2(L–L)]X complexes (X=ClO4, L–L=bipy (7), L–L=phen (8), L–L=dppe (9) X=SO3CF3, L–L=dppm (10)). Dithiocarbamate- or acetate salts can be added to solutions of ‘Au(mes)2X’ (obtained by removal of two chloride anions in 1) leading to the neutral compounds cis-[Au(mes)2(L–L)] (L–L=S2CNR2 (R=Me (11), Et (12), Bz (13)), O2CCF3 (14)). The structures of cis-[Au(mes)2Cl(PPh3)] (2) and cis-[Au(mes)2Cl]2 (6) have been established by an X-ray diffraction study.