A novel cobalt(II)–molybdenum(V) phosphate organic–inorganic hybrid polymer

A new organic–inorganic hybrid cobalt(II)–molybdenum(V) phosphate polymer incorporating piperazine (pip), (H2pip)3[Co3Mo12O24(OH)6(PO4)8(H1.5pip)4]·5(H2O), was prepared under hydrothermal conditions. As revealed by single-crystal X-ray diffraction studies, the material is modular, built from a secondary building block composed of two anionic hexameric polyoxomolybdophosphate [Mo6O12(OH)3(PO4)4]9− moieties, bridged by a central octahedral Co2+ centre. The sandwich-type {Co[Mo6O12(OH)3(PO4)4]2}16− dimers are connected via tetrahedral Co2+ metal centres, forming an infinite one-dimensional polymer. The compound constitutes the first example of a reduced sandwich-type cobalt–molybdenum phosphate in which the organic moiety (pip) is effectively coordinated to the inorganic backbone of the polymer, in this case via the tetrahedrally coordinated Co2+ centres. The magnetic behaviour of this material was investigated in the temperature range 4–298 K.