Crystal Structure of 2-Amino-5-Nitropyridinium Dihydrogenphosphate Monophosphoric Acid: Influence of the Polyanion Charge on the Formation of Centrosymmetric Structure

Author： Zaccaro J. Bagieu-Beucher M. Ibanez A. Masse R.

Publisher： Academic Press

ISSN： 0022-4596

Source： Journal of Solid State Chemistry, Vol.124, Iss.1, 1996-06, pp. : 8-16

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Abstract

Chemical preparation and structural characterization by single crystal X-ray diffraction are given for the 2-amino-5-nitropyridinium dihydrogenphosphate monophosphoric acid (2A5NPDPP): C 5 H 6 N 3 O + 2 ·H 2 PO - 4 ·H 3 PO 4 . Crystals are monoclinic, space group P 2 1 / n with a = 16.050(16), b = 8.985(5), c = 8.830(5) A, beta = 96.86(7)#°, V = 1264(2) A 3 , Z = 4. The structure was refined to R = 0.050 ( R W = 0.056) for 2224 reflections with I > 3sigma( I ). The structural arrangement can be described as inorganic layers of H 5 P 2 O - 8 units separated by infinite organic chains of chromophores. Strong hydrogen bonds maintain a two-dimensional cohesion between phosphate tetrahedra while weaker ones link the organic cations together and to the anionic subnetwork. The influence of the polyanion charge on the symmetry of the cationic packing is discussed with respect to the herringbone structure of the 2-amino-5-nitropyridinium dihydrogenphosphate (2A5NPDP), a nonlinear optical crystal built with the same chromophores.