η5-C5H5- and η5-C5Me5-metal complexes (M=Zr(IV) and Hf(IV)) with the sulfur-rich dithiolate C8H4S8 ligand and high electrical conductivities of their oxidized species

Zr(η5-C5H5)2(C8H4S8), [NMe4][Zr(η5-C5H5)(C8H4S8)2], [NMe4][Zr(η5-C5Me5)(C8H4S8)2], and [NMe4][Hf(η5-C5Me5)(C8H4S8)2] (C8H4S82−=2-{(4,5-ethylenedithio)-1,3-dithiole-2-ylidene}-1,3-dithiole-4,5-dithiolate(2-)) were prepared by reactions of Zr(η5-C5H5)2Cl2, Zr(η5-C5H5)Cl3, Zr(η5-C5Me5)Cl3 or Hf(η5-C5Me5)Cl3 with [NMe4]2(C8H4S8) in tetrahydrofuran. They were oxidized by iodine or TCNQ (7,7,8,8-tetracyano-p-quinodimethane) in dichloromethane or in acetone to afford 1.0-, 1.3- or 1.8-electron oxidized complexes, [Zr(η5-C5H5)2(C8H4S8)]+, [Zr(η5-C5H5)(C8H4S8)2]0, [M(η5-C5Me5)(C8H4S8)2]0.3+ and [M(η5-C5Me5)(C8H4S8)2]0.8+ (M=Zr(IV) and Hf(IV)) species having the I3− ion or the TCNQradical dot− radical anion as a counter ion, with the C8H4S8 ligand-centered oxidation. They exhibited electrical conductivities of 1.6×10−1–7.6×10−4 S cm−1 measured for compacted pellets at room temperature. Particularly, [Zr(η5-C5H5)2(C8H4S8)]+ and [M(η5-C5Me5)(C8H4S8)2]0.3+ (M=Zr(IV) and Hf(IV)) complexes as well as [Ti(L)(C8H4S8)2]0.3+ (L=η5-C5H5 and η5-C5Me5) species showed high electrical conductivities (0.010–0.16 S cm−1).