Cages on a plane: a structural matrix for molecular 'sheets'

A family of heterometallic Anderson-type 'wheels' of general formula [(M2M5II)-M-III(hmp)(12)](4+) (M-III = Cr or Al and M-II = Ni or Zn, Hhmp = 2-pyridinemethanol) has been extended to include M-III = Cr or Al and M-II = Co, Fe, Mn or Cu, affording five new species of formulae [Cr2Co5(hmp)(12)](ClO4)(4) (1), [Cr2Fe5(hmp)(12)](ClO4)(4) (2), [Cr2Mn5(hmp)(12)](ClO4)(4) (3), [Cr2Cu5(hmp)(12)](ClO4)(2)(NO3)(2) (4) and [Al2Co5(hmp)(12)](ClO4)(4) (5). As per previous family members, the metallic skeleton common to the cations of 1-5 describes a centred hexagon with the two M-III sites disordered around the outer wheel, with the exception of compound 4 where the Cu-II sites are localised. A structurally related, but enlarged planar disc possessing a [(M6MII)-M-III] hexagon capped on each edge by a Cu-II ion can be formed, but only when M-III = Al and M-II = Cu. In [(Al6Cu7II)-Cu-III(OH)(12)(hmp)(12)](ClO4)(6)(NO3)(2) (6) the Anderson moiety contains a central, symmetry-imposed octahedral Cu-II ion surrounded by a wheel of Al-III ions. Solid-state dc susceptibility and magnetisation measurements reveal the presence of competing exchange interactions in 1-5, and very weak antiferromagnetic exchange between the Cu-II ions in 6 which may be intra-and/or intermolecular in nature.