Acta Cryst. (2008). E64, m144-m145  [ doi:10.1107/S1600536807065026 ]

Bis(guanidinium) bis(4-hydroxypyridine-2,6-dicarboxylato-³O²,N,O⁶)nickelate(II) dihydrate

H. Aghabozorg, E. Motyeian, J. Attar Gharamaleki, J. Soleimannejad, M. Ghadermazi and E. Spey Sharon

Abstract: The reaction of nickel(II) nitrate hexahydrate, guanidine (G) and 4-hydroxypyridine-2,6-dicarboxylic acid (hypydcH₂) in a 1:2:2 molar ratio in aqueous solution resulted in the formation of the title compound, (CH₆N₃)₂[Ni(C₇H₃NO₅)₂]·2H₂O or (GH)₂[Ni(hypydc)₂]·2H₂O. The six donor atoms of the two 4-hydroxypyridine-2,6-dicarboxylate or (hypydc)^2- ligands form a distorted octahedral arrangement around the Ni^II centre. Considerable C-O stacking interactions between the CO groups of carboxylate fragments and the pyridine rings of (hypydc)^2- with a distance of 3.3212 (8) Å are observed. In the crystal structure, a wide range of noncovalent interactions consisting of hydrogen bonding (of the types O-HO and N-HO), ion pairing, and - [centroid-centroid distance 3.8037 (5) Å], N-H and C-O stacking interactions connect the various components into a supramolecular structure.

Online 12 December 2007

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