Aufbau Approach to Multimetallic Ensembles Based on Tetrathiooxalate: [Cp*4Rh4(C2S4)2]2+, [Cp*3Rh2Ru(C2S4)]+, and [Cp*6Rh6(C2S4)2]4+
Experiments aimed at the characterization of new coordination modes for tetrathiooxalate (TTO) are described. Cyclic voltammetric (CV) measurements on Cp*2Rh2(C2S4) (1) revealed an irreversible oxidation as part of an ECE process that results in the chemically reversible dimerization of 1+. Treatment of 1 with CpFe[C5H4C(O)Me]BF4 followed by anion exchange gave [Cp*4Rh4(C2S4)2](BPh4)2, the dication of which consists of a dimer of 1+ linked through two pairs of Rh−S bonds. A second new bonding mode for TTO was generated by treatment of 1 with [Cp*Ru(MeCN)3]PF6 to give [Cp*3Rh2Ru(C2S4)]+ (3) wherein Cp*Ru+ is η5-bonded to one RhS2C2 ring. A third new bonding mode for TTO is illustrated by [Cp*6Rh6(C2S4)2]4+, formed by the reaction of Cp*Rh(MeCN)32+ and 1. The structure can be viewed as a dimer of3, except that there are no M−M bonds: the Cp*Rh2+ fragments are bonded via an η4-interaction to RhS2C2 rings. Furthermore, the [Cp*3Rh3(C2S4)]2+ subunits, which are otherwise isoelectronic with 3, dimerize, such that all eight sulfur atoms are triply bridging.
Holloway, G. A.; Klausmeyer, K. K.; Wilson, S. R.; Rauchfuss, T. B. "Aufbau Approach to Multimetallic Ensembles Based on Tetrathiooxalate: [Cp*4Rh4(C2S4)2]2+, [Cp*3Rh2Ru(C2S4)]+, and [Cp*6Rh6(C2S4)2]4+," Organometallics 2000, 19, 5370-5375.