Pentamethylcyclopentadienyl rhodium complexes

We report syntheses and structures of pentamethylcyclopentadienyl (Cp*) rhodium(III) and rhodium(I) complexes. Dicationic rhodium(III) complexes, [Cp*Rh(bpy)(MeCN)](PF6)(2) and [Cp*Rh(vbpy)(MeCN)](PF6)(2) (bpy = 2,2'-bipyridyl and vbpy = 4-vinyl-2,2'-bipyridyl), were prepared by treatment of [Cp*Rh(MeCN)(3)](PF6)(2) with bpy and vbpy, respectively. The monocationic rhodium(III) complex, [Cp*Rh(Me(4)phen)Cl]Cl (Me(4)phen = 3,4,7,8-tetramethyl-1,10-phenanthroline), was prepared by treatment of the chloride-bridged rhodium dimer, [Cp*RhCl2](2), with Me(4)phen. Two rhodium(I) complexes were synthesized via reduction of their rhodium(III) counterparts using two different methods: Cp*Rh(bpy) was produced via a new route involving treatment of [Cp*Rh(bpy)Cl]Cl with thallium formate in dry acetonitrile, whereas [Cp*Rh(Me(4)phen)Cl]Cl was reduced with Na(Hg) to give Cp*Rh(Me(4)phen). The colors of the Rh(I) complexes are attributable to relatively intense visible-region MLCT absorptions. (C) 2014 Elsevier Ltd. All rights reserved.