2,9-Dimethyl-1,10-phenanthrolin-1-ium (6-carboxy-4-hydroxypyridine-2-carboxylato-κ3O2,N,O6)(4-hydroxypyridine-2,6-dicarboxylato-κ3O2,N,O6)nickelate(II) 2.35-hydrate: a proton-transfer compound

Abstract

The title proton-transfer compound, (C14H13N2)[Ni(C7H3NO5)(C7H4NO5)]·2.35H2O, consists of an [Ni(hypydc)(hypydcH)]− anion, a dmpH+ cation and 2.35 uncoordinated water molecules (where hypydcH2 = 4-hydroxypyridine-2,6-dicarboxylic acid and dmp = 2,9-dimethyl-1,10-phenanthroline). The NiII atom is coordinated by two N atoms and four O atoms from the carboxylate groups of the (hypydc)2− and (hypydcH)− ligands, forming a distorted octahedral environment. In the anion, the two pyridine rings are inclined to one another by 89.24 (10)°. In the crystal, cations are linked via O—H...O hydrogen bonds forming dimers, graph-set [R22(16)], centered about inversion centers. These dimers are further linked by other cation O—H...O hydrogen bonds, graph-set [R66(42)], forming a two-dimensional network in (011). Additional intermolecular O—H...O, N—H...O, N—H...N, and weak C—H...O hydrogen bonds, and π–π interactions [shortest centroid–centroid distance = 3.5442 (14) Å], connect the two dimensional networks, forming a three-dimensional arrangement. The H atoms of one of the methyl groups are disordered over two sites with equal occupancy.