Heterometallic bromo-bridged complexes with a Re(CO)3 fragment

Heterobimetallic complexes in which half-sandwich complexes of ruthenium(), rhodium() and iridium() are connected by three bromo-bridges to Re(CO)3 have been prepared from metathesis reactions of [RuBr(μ-Br)(arene)]2 (arene = C6H6, C6H3Et3-1,3,5 or p-cymene) or [MBr(μ-Br)Cp*]2 (M = Rh or Ir) with [Re(μ-Br)(CO)3(C4H8O)]2. The crystal structures of [(arene)Ru(μ-Br)3Re(CO)3] (arene = C6H6 or C6H3Et3-1,3,5) and [Cp*M(μ-Br)3Re(CO)3] (M = Rh or Ir) have been determined by X-ray analysis. In solution all complexes were shown to be in a dynamic equilibrium with isomeric ionic compounds of the general formula [M2(μ-Br)3(π-ligand)2][Re2(μ-Br)3(CO)6] (M = Ru, Rh or Ir). The solid state structures of [Ru2(μ-Br)3(C6H3Et3-1,3,5)2][Re2(μ-Br)3(CO)6] and [Ru2(μ-Br)3(p-MeC6H4Pr )][Re2(μ-Br)3(CO)6] are described.