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

Heterobimetallic complexes in which half-sandwich complexes of ruthenium(II ), rhodium(III) and iridium(III) are connected by three bromo-bridges to Re (CO)(3) have been prepared from metathesis reactions of [RuBr(mu-Br)(arene) ](2) (arene=C6H6, C6H3Et3-1,3,5 or p- cymene) or [MBr(mu-Br)Cp*](2) (M=Rh o r Ir) with [Re(mu-Br)(CO)(3)(C4H8O)](2). The crystal structures of [(arene) Ru(mu-Br)(3)Re(CO)(3)] (arene=C6H6 or C6H3Et3-1,3,5) and [Cp*M(mu-Br)(3)Re( CO)(3)] (M=Rh or Ir) have been determined by X-ray analysis. In solution al l complexes were shown to be in a dynamic equilibrium with isomeric ionic c ompounds of the general formula [M-2(mu-Br)(3)(pi-ligand)(2)][Re-2(mu-Br)(3 )(CO)(6)] (M=Ru, Rh or Ir). The solid state structures of [Ru-2(mu-Br)(3)(C 6H3Et3-1,3,5)(2)][Re-2(mu-Br)(3)(CO)(6)] and [Ru-2(mu-Br)(3)(p-MeC6H4Pri)][ Re-2(mu-Br)(3)(CO)(6)] are described.