Hexakis(imidazole-N³)nickel(II) Carbonate Pentahydrate

The crystal structure of the title complex, [Ni(C₃H₄N₂)₆]CO₃.5H₂O, isostructural with the Cd, Co and Ru analogues, is built up from cationic and anionic sheets parallel to the basal plane of the hexagonal unit cell. The former contain the [Ni(C₃H₄N₂)₆]²⁺ cations and the latter the CO₃^2- anions, together with the hydration water molecules. These are disordered at both sides of the P6₃/m mirror plane, which thus exists in an average sense only. The sheets are linked by an extensive hydrogen-bonding system, involving the non-coordinated NH imidazole groups, the hydration water molecules and the O atoms of the carbonate anions. The latter are acceptors of nine simultaneous strong hydrogen bonds.

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