On the new low-dimensional organic-inorganic hybrid solids Cu 4(bipy)4[V4P2O19] ·nH2O (n ∼ 5) and Cu2(bipy)2[V 2P2O12] with linear [V4P 2O19]8- and cyclic [V2P 2O12]4- oligomers

Abstract

The new hybrid organic-inorganic copper oxovanadium phosphates of composition Cu4(bipy)4V4O11(PO 4)2·nH2O (n ∼ 5) (1) and Cu 2(bipy)2V2P2O12 (2) (bipy = 2, 2′-bipyridine) adopting the triclinic symmetry were obtained by soft hydrothermal routes. Both structures present different oxovanadium phosphate anionic units, resulting from the vertex-sharing of PO4 and VO 4 tetrahedra, which are coordinated to copper diimine cationic groups to form a ID framework. The VPO structures are reminiscent of the known connectivity and geometry of polyphosphate anions. For the two compounds, the magnetic copper(II) centres are square pyramidally coordinated with two nitrogen atoms of the neutral diimine ligand and three oxygen atoms of the oxovanadium phosphate subunit. The CuN2O3 pyramids are linked together by oxo-bridges involving PO4 tetrahedra in Cu2(bipy) 2V2P2O12 with the closest Cu-Cu distances corresponding to 4.98 Å. Edge-sharing of the copper pyramids in Cu4(bipy)4V4O11(PO4) 2·nH2O results in