Syntheses and structures of heterobimetallic complexes derived from [Ga(edt)2]− as a metalloligand (edt = −SC2H4S−): Potential precursors for ternary materials MGaS2 (M = Cu or Ag)

Metathesis reaction between equimolar amount of [Et4N][GaCl4] and Na2edt in methanol resulted in the formation of the dichloro complex [Et4N][Ga(edt)Cl2] (1), whereas reaction of [Et4N][GaCl4] with two equivalents of Na2edt in methanol gave the complex [Et4N][Ga(edt)2] (2) which can act as a metalloligand. Treatment of 2 with M(PPh3)2NO3 in DMF/CH2Cl2 afforded the heterobimetallic complexes [Ga(edt)2M-(PPh3)2] (M = Cu 3, Ag 4) in moderate yields. The structures of 1–4 were determined by single-crystal X-ray diffraction analyses. Both [Ga(edt)Cl2]− and [Ga(edt)2]− anions have a distorted tetrahedral geometry. The former consists of one five-membered ring formed by chelating dithiolate and two terminal chloride atoms while the latter consists of two five-membered rings formed by two the chelating dithiolates. Complexes 3 and 4 consist of metalloligand [Ga(edt)2]− anion chelated to [M(PPh3)2]+ via the sulfur atoms. Both tetrahedrally coordinated Ga and Cu(Ag) atoms are bridged by two sulfur atoms, forming a planar “GaS2M” (M = Cu, Ag) core. Thermogravimetry analysis revealed that heterobimetallic complexes 3 and 4 decomposed to give the corresponding ternary metal sulfide materials.