Acta Cryst. (2005). E61, o2635-o2637  [ doi:10.1107/S1600536805022737 ]

N,N'-Dimethylpiperazinium(2+) bis[methylenehydrogendiphosphonate(1-)]

Z. Yuan and W. Clegg

Abstract: The asymmetric unit of the title compound, C₆H₁₆N₂²⁺·2(HO)₂(O)PCH₂P(O)₂(OH)^-, contains two singly charged diphosphonate anions and two half-cations, each doubly charged cation lying on an inversion centre. Single deprotonation of methylenediphosphonic acid to give a salt with an organic amine is unprecedented, double deprotonation being normal. All N-H and O-H groups act as hydrogen-bond donors in the crystal structure, with unprotonated O atoms as the acceptors, giving a three-dimensional network.

Online 20 July 2005

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