Surface-Assisted Synthesis and Behavior of Dimetallic Mixed-Metal Complexes [M2Cl2(μ-Cl)4(CO)6M′(L)2] (M = Ru, Os; M′ = Fe, Co; L = CH3CH2OH, H2O)

The reductive carbonylation of ruthenium and osmium halides in the presence of cobalt and iron surfaces was studied. In these surface‐assisted reactions the metal surface plays an active role in releasing metal ions, which can be used for the in situ synthesis of mixed‐metal compounds. A linear, dimetallic, chlorido‐bridged, trinuclear complex [Ru2Cl2(μ‐Cl)4(CO)6Co(CH3CH2OH)2] was obtained by the interaction between reducing RuCl3 and the cobalt surface. In the reaction the RuCl3 is reduced with carbon monoxide in the presence of a solid cobalt surface in ethanol solution. During the reduction of the RuCl3 the cobalt surface was simultaneously corroded, releasing cobalt cations. In addition to [Ru2Cl2(μ‐Cl)4(CO)6Co(CH3CH2OH)2], the reaction also produced other trinuclear complexes and mononuclear products, such as a bent and linear dimetallic, chlorido‐bridged complex with the aqua ligand [Ru2Cl2(μ‐Cl)4(CO)6Co(H2O)2] and ionic [RuCl3(CO)3]2[Co(H2O)6]. The carbon monoxide reduction of RuI3 produced the ionic complex [RuI3(CO)3]2[M′(H2O)6] (M′ = Fe, Co) in the presence of iron, stainless steel or cobalt. Iodido‐bridged trinuclear mixed‐metal complexes were not observed. The surface‐assisted process proved to be useful with other metal combinations as well. When RuCl3 was replaced with OsCl3, a variety of trinuclear mixed‐metal complexes, such as [Os2Cl2(μ‐Cl)4(CO)6Co(CH3CH2OH)2] and ionic [OsCl3(CO)3]2[M(H2O)6] (M = Fe, Co), were obtained, depending on the metal surface used. Due the lability of the chlorido‐bridged trinuclear complexes, the possible decomposition steps of [M2Cl2(μ‐Cl)4(CO)6M′(CH3CH2OH)2] (M = Ru, Os; M′ = CO, Fe) were studied computationally, using DFT methods. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)