Acta Crystallographica Section B

Structural Science

Volume 58, Part 3 Number 2 (June 2002)

research papers

Acta Cryst. (2002). B58, 519-529 [ doi:10.1107/S0108768102004020 ]

Charge density study of hydrogen [(2,4-diaminopyrimidin-1-io)methyl]phosphonate monohydrate

M. Slouf, A. Holy, V. Petrícek and I. Cisarova

Abstract: The crystal structure and charge density of hydrogen (2,4-diaminopyrimidin-1-io)methyl]phosphonate monohydrate, C₅H₉N₄O₃P·H₂O, have been determined by means of single-crystal X-ray diffraction. Diffraction data were collected at 105 K with Mo K [alpha] radiation to a resolution of sin [theta] / [lambda] = 1.08 Å^-1. A four-circle diffractometer equipped with a CCD area detector was used to collect 50 161 reflections over 3 d. 6082 unique reflections with I > 3 [sigma] (I) were used in the multipole model to map the deformation electron density and gave the final statistical factors R(F) = 0.0329, wR(F) = 0.0235 and g.o.f. = 1.37. Structure determination revealed that two O atoms in the crystal structure of the title compound act as hydrogen-bond acceptors for more than one hydrogen bond. Examination of deformation electron density maps showed preferential polarization of the lone-pair electron density of the two O atoms into the shortest hydrogen bonds.

Keywords: charge density study; polarization; hydrogen bonds.