Solvatomorphs of dimeric transition metal complexes based on the V4O12 cyclic anion as building block: Crystalline packing and magnetic properties

摘要

Dinuclear [{M(phen)(2)}(2)V4O12] center dot C6H12O center dot H2O (M = Co-II 1, Mn-II 2, Ni-II 3 and Cu-II 4) and [{Cu(phen)(2)}(2)-V4O12] center dot 3.5H(2)O 5 has been prepared by biphasic and hydrothermal syntheses, respectively. All five structures exhibit the {V4O12}(4) cluster in a chair-like configuration, covalently bonded to two [M(phen)(2)](2+) fragments, producing a super-exchange magnetic phenomenon. The magnetic study of complexes 1-5 shows that they are very weak antiferromagnetically coupled systems, with J values of -0.14, 2; -0.64, 3 and -0.23, 4 cm (1). Complexes 1 to 3 correspond to isostructural compounds in which the cyclo-vanadate group acts as a bidentate bridged ligand. In the copper complexes (4 and 5) the {V4O12}(4) anion presents the novel monodentate bridging mode, and therefore a more significant distortion from the chair-like condiguration. The mentioned complexes, together with that reported in the literature, permit to conclude that it is quite common for a single molecular species to exist in more than one crystalline arrangement. A detailed analysis of the structures of 1-4 shows that the crystal symmetry cannot be strictly centrosymmetric, due to the presence of the cyclohexanol molecule with a single -OH group in the lattice.