Dipotassium tetra-aqua-bis-(µ-citrato-κ(4) O:O',O'',O''')nickelate(II) tetra-hydrate.

The title complex, K2[Ni2(C6H5O7)2(H2O)4]·4H2O, is a dinuclear centrosymmetric anionic octa-hedral complex, involv-ing citrates as tridentate and bridging ligands, and coordinating water mol-ecules. An extensive network of hydrogen bonds connects the complex anions through the two unique uncoordinating water mol-ecules. The K(+) counter cation is surrounded by seven O atoms in the form of an irregular polyhedron and further stabilizes the crystal packing.