Disodium diaqua-bis-(methyl-enedi-phos-pho-nato-κO,O')cobaltate(II) dihydrate.

In the title compound, Na(2)[Co(CH(4)O(6)P(2))(2)(H(2)O)(2)]·2H(2)O, the asymmetric unit is composed of one methyl-enediphospho-nate ligand and one water mol-ecule, which both are coordinated to a Co(II) atom, as well as a non-coordinated water mol-ecule and a sodium cation. The Co(II) atom occupies a special position on a crystallographic inversion centre. The slightly distorted Co(II)O(6) octa-hedral coordination environment is composed of two bidentate methyl-enediphospho-nate ligands and two coordinated water mol-ecules in trans positions. The sodium ion is octa-hedrally coordinated to six O atoms with Na-O distances ranging from 2.3149 (12) to 2.6243 (12) Å. An extensive three-dimensional network of inter-molecular as well as intra-molecular O-H⋯O and C-H⋯O hydrogen bonding inter-acions is present.