An unsupported metal hydroxide for the design of molecular μ-oxo bridged heterobimetallic complexes

A terminal and unsupported chromium(iii) hydroxide is reported.

Pyridinium diaqua-bis-(methyl-enediphospho-nato-κO,O')chromate(III) tetra-hydrate

In the title complex, (C₅H₆N)[Cr(CH₄O₆P₂)₂(H₂O)₂]·4H₂O, the Cr^III atom, lying on an inversion centre, is coordinated by two bidentate methyl­ene diphospho­nate ligands and two water molecules in a distorted octa­hedral coordination geometry. The pyridinium cation is located on an inversion centre, with an N atom and a C atom sharing a position each at a half occupancy. A three-dimensional network is constructed by O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds between the pyridin­ium cation, complex anion and uncoordinated water mol­ecules.