Clusters as Ligands, Part 3: Generation of Tricobalt Cluster Carboxylate-bridged Iron - Cobalt and Manganese - Cobalt Mixed-metal Alkoxide Cubes from Iron and Manganese Tricobalt Cluster Metal Carboxylates


The reaction of the cluster-substituted carboxylic acid, (CO)9Co3CCOOH, with M(CH3CO2)2 permits the isolation of M2(CO)9Co3CCO24(THF)2, M = Mn (1), Fe (2), Co (3) respectively. Single crystals could not be obtained directly from any of these compounds; however, the slow redox degradation of Hg(CO)9Co3CCO22 in THF leads to crystalline [Co2((CO)9Co3CCO2)4(THF)2], which has been characterized by single crystal X-ray structure analysis. Both compounds 1 and 2 react with methanol and the products [MIII2CoII2(MeO)6(MeOH)2(CO)9Co3CCO24] · 2MeOH, M = Mn (4), Fe (5) respectively, have been isolated as crystalline solids. The formulation of these new mixed-metal cubane clusters is based on analytical data, single crystal X-ray structure analysis, and the Mössbauer spectrum of 5. The inner CoII centers are derived from sacrificial decomposition of the tricobalt clusters during precipitation of the product. For both 4 and 5 the magnetic susceptibility data show high room temperature magnetic moments which decrease with decreasing temperature consistent with weak antiferromagnetic coupling between the core metal centers and with S = 0 ground states. The formation of these unusual carboxylate coordinated mixed-metal alkoxide cubes derives from the properties of a transition metal cluster as a substituent as well as its tendency to engage in redox chemistry with other metal species. © 1997 Elsevier Science S.A.



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© 1997 Elsevier, All rights reserved.

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01 Jan 1997