Acta Crystallographica Section B

Structural Science

Volume 57, Part 3 (June 2001)

research papers

Acta Cryst. (2001). B57, 359-365 [ doi:10.1107/S0108768100020048 ]

Chemical bonding in energetic materials: -NTO

E. A. Zhurova and A. A. Pinkerton

Abstract: The electron density and related properties of the quasi-stable [beta] form of 5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO; space group P2₁/c) have been determined from a low-temperature [100 (1) K] X-ray diffraction experiment. Intensities were measured with a 2K CCD Bruker diffractometer using Ag K [alpha] radiation. Two detector settings, several [varphi] settings, 0.3° [omega] scans and 160 s exposure time per frame gave R_int = 0.0215 for 68 989 (4080 unique) reflections and (sin [theta] / [lambda] )_max = 1.23 Å^-1. The Hansen-Coppens [Acta Cryst. (1978), A34, 909-921] multipole model as implemented in the XD program gave R = 0.0333 (all reflections), which allowed calculation of the electron density, Laplacian and electrostatic potential distributions. The bonding (3,-1) critical points and the molecular dipole moment of 3.2 (1) D were also obtained. Chemical bonding in the molecule is discussed.

Keywords: bonding; electron density; low-temperature diffractometry.