Structures of sulfur-rich dithiolate-gold(I) complexes and their oxidation

[NMe4][Au(PEt3)(C3S5)], [NMe4][Au(PPh3)(C3S5)], [NMe4][Au(PEt3)(C8H4S8)], [N-methylpyridinium][Au(PPh3)(C8H4S8)], [(PEt3)Au–C3S5–Au(PEt3)], and [(PEt3)Au–C8H4S8–Au(PEt3)] [C3S52−=4,5-disulfanyl-1,3-dithiole-2-thionate(2−); C8H4S82−=2-{(4,5-ethylenedithio)-1,3-dithiole-2-ylidene}-1,3-dithiole-4,5-dithionate(2−)] were prepared. They exhibited first oxidation potentials due to the dithiolate ligand-centered oxidation at −0.30 to +0.21 V (vs. Ag/Ag+) in dichloromethane. They were reacted with iodine or 7,7,8,8-tetracyano-p-quinodimethane (TCNQ) to afford one-electron-oxidized species [Au(PEt3)(C8H4S8)] and [(L)Au–C8H4S8–Au(L)](TCNQ)1.0–1.1, (L=PEt3 and PPh3) and further-electron-oxidized species [Au(PEt3)(S–S)]I3.3–5.7, [Au(PPh3)(S–S)]I12–13, [(PEt3)Au–(S–S)–Au(PEt3)]I3.3–5.5 (S–S=C3S52− and C8H4S82−) and [(PPh3)Au–C8H4S8–Au(PPh3)]I12. ESR spectra of the oxidized species suggest the C3S5 and C8H4S8 ligand-centered oxidation. The oxidized C8H4S8-complexes showed electrical conductivities of 10−4–10−2 S cm−1 measured for compacted pellets at room temperature. X-ray crystal structures of [NMe4][Au(PPh3)(C3S5)]CH2Cl2, [(PEt3)Au–C3S5–Au(PEt3)] and [(PEt3)Au–C8H4S8–Au(PEt3)] were revealed.