Triaqua-(N,N-di-2-pyridylpyrimidine-2,4-diamine)cobalt(II) fumarate.

The Co atom in the title compound, [Co(C(14)H(12)N(6))(H(2)O)(3)]C(4)H(2)O(4), has a mer-CoN(3)O(3) octa-hedral coordination arising from the tridentate N(2),N(4)-di-2-pyridylpyrimidine-2,4-diamine (tpda) ligand and three coordinated water mol-ecules. The asymmetric unit contains two fumarate half-anions, both completed by inversion symmetry. A network of N-H⋯O and O-H⋯O hydrogen bonds leads to a three-dimensional network in the crystal structure.