Hexaaquacobalt(II) bis(hypophosphite) and hexaaquacobalt(II)/nickel(II) bis(hypophosphite)

The title compounds, hexaaquacobalt(II) bis(hypophosphite), [Co(H2O)(6)](H2PO2)(2), and hexaaquacobalt(II)/nickel(II) bis(hypophosphite), [Co0.5Ni0.5 (H2O)(6)](H2PO2)(2), are shown to adopt the same structure as hexaaquamagnesium(II) bis(hypophosphite). The packing of the Co(Ni) and P atoms is the same as in the structure of CaF2. The Co-II (Ni-II) atoms have a pseudo-face-centred cubic cell, with a = b similar to 10.3 Angstrom, and the P atoms occupy the tetrahedral cavities. The central metal cation has a slightly distorted octahedral coordination sphere. The geometry of the hypophosphite anion in the structure is very close to ideal, with point symmetry mm2. Each O atom of the hypophosphite anion is hydrogen bonded to three water molecules from different cation complexes, and each H atom of the hypophosphite anion is surrounded by three water molecules from further different cation complexes.