Heterometallic hexanuclear isobutyrate clusters based on di- and tripodal alcohols

Four hexanuclear coordination clusters containing {(M4M2III)-M-II} cores of edge-sharing coordination octahedra exemplify how mixed-spin derivatives of a homonuclear parent structure. [(Mn4MnL8)-M-II-L-2III(N-O)(4)], can be realized by a ligand 'shrink-wrapping' approach, resulting in [(Mn2Co2Mn2L8)-Co-II-Mn-II-L-III(N-O)(4)](-) and [(Co4F4L8)-F-II-L-III(N-O)(4)]-type clusters (L= isobutyrate, N-O = methyldiethanolamine, n-butyldiethanolamine, or triethanolamine). The resulting core structures are either virtually isostructural to the parent structure or differ in the placement of the peripheral metal ions, depending on the mix of structure-directing carboxylate and alkoxyamine ligands with large, flexible alkyl chains. Whereas the {(Mn4Mn2III)-Mn-II} and {(Co4Fe2III)-Fe-II} complexes show dominant antiferromagnetic exchange, ferrimagnetic coupling features are exhibited by two {(Mn2Co2Mn2III)-Co-II-Mn-II} clusters. (c) 2010 Elsevier Ltd. All rights reserved.