| Abstract: | In the title compound, {K2Ni(C5O5)2(H2O)2]·4H2O}n, the Ni atom lies on an inversion centre. Two inversion‐related croconate 4,5‐dihydroxy‐4‐cyclopentene‐1,2,3‐trionate(2?)] ligands and an NiII ion form a near‐planar symmetrical Ni(C5O5)2]2? moiety. The near‐square coordination centre of the moiety is then extended to an octahedral core by vertically bonding two water molecules in the Ni(C5O5)2(H2O)2]2? coordination anion. The crystal structure is characterized by a three‐dimensional network, involving strong K?O?K binding, K?O—Ni binding and hydrogen bonding. |
