Metal Complexes with Two Different Sulfur Containing Ligands-ii*

The synthesis and characterization of a series of mixed l,l-/l,2-dithiolene complexes, M[S2C2(CN)2] [SüCNR*]* with z = — 1, M = Ni, Cu, Pd, Pt and with 2 = 0, M = Ni, Cu, Au, M [S2C2(CN)2] [S2C NC N]2' , M = Ni, Pd, and N i[S2C2(CN)2] [S2COC2H5] are reported. Voltammetric studies in dichloromethane revealed that the mixed complexes could be oxidized in a one electron step, the half-wavepotentials of which were generally in the middle between those for the unmixed complexes. The C—N stretching frequencies observed in the i.r. spectra of the M [S2C2(CN)2] [S2CNR2]2 complexes are reported. IN T R O D U C T IO N T here is a growing interest in metal com plexes containing tw o different sulfur donor ligands, especially those with the 1,1and 1,2-dithiolato ligand system s. N ickel bis-com plexes with tw o different 1,2-dithiolato ligands were reported[l], and the exchange reactions of these and related 1,2-dithiolenes w ere studied with voltammetric techniques [1,2], Tris complexes with mixed 1,1and 1,2-dithiolene ligands were also prepared and investigated recently [3,4]. In the course of investigating mixed metal bis-complexes we found electron transfer series in Ni, Cu and Au complexes containing an 1,2as well as an 1,1-dithiolato ligand, M(S2C2(CN)2)(S2CNbu2)*, with z = — 1 and 0 [5]. The present paper describes the results of the voltammetric studies made on a series of mixed complexes derived from the same and some related sulfur donor ligands [6], R ESU LTS A N D D ISC U SSIO N Preparations Analytical data for the newly prepared complexes correspond with the formulas given (Table 1). Colours, melting points and conductances are given in Table 2.