μ-Diborolyl triple-decker complexes with carbonyl ligands: Synthesis, structures and electrochemistry

Triple-decker complexes with a bridging diborolyl ligand CpCo(m-1,3-C3B2Me5)M(CO)3 (M = Mn, 2; Re, 3), CpCo(m-1,3-C3B2Me5)Ru(CO)2Cl (4) and CpCo(m-1,3-C3B2Me5)Ru(CO)(m-CO)2Ru(CO)Cp (5) were synthesized by reaction of the sandwich anion [CpCo(1,3-C3B2Me5)]e (1) with [(naphthalene)Mn(CO)3]þ, [Re(CO)3(THF)2Br]2, or [Ru(CO)3Cl2]2. Structures of 4 and 5 were determined by X-ray diffraction. The spectroelectrochemical behaviour of compounds 2 and 3 was studied. IR-spectroscopical and computational data suggest that anion 1 is significantly stronger donor than Cp but slightly weaker than Cp*.