Acta Crystallographica Section B

Structural Science

Volume 52, Part 6 (December 1996)

research papers

Acta Cryst. (1996). B52, 923-931 [ doi:10.1107/S010876819600794X ]

Atomic displacement parameters for Ni(ND₃)₄(NO₂)₂ from 9 K X-ray and 13 K time-of-flight neutron diffraction data

B. B. Iversen, F. K. Larsen, B. N. Figgis, P. A. Reynolds and A. J. Schultz

Abstract: Structural parameters derived from 9 1) K X-ray diffraction data and 13 (1) K time-of-flight neutron diffraction data on perdeuterated tetraamminedinitronickel(II), Ni(ND₃)₄(NO₂)₂, are compared. It is shown that excellent agreement can be obtained for both positional and thermal parameters derived separately from the two experiments, provided that great care is taken in all steps of the process, including data collection, data reduction, and nuclear and electronic structure refinement. The mean difference in the thermal parameters, <|U_ij|>, is as low as 0.00034 Å² and <(U_ij/)²>^1/2 = 1.92, showing that, even without any form of scaling between the parameters, the same values can be obtained. This, compared with other such studies, indicates that time-of-flight neutron diffraction data can give structural information of a quality comparable to monochromatic neutron diffraction. The excellent correspondence between the thermal parameters derived separately from X-ray and neutron diffraction data gives confidence in the deconvolution of the thermal motion from the X-ray diffraction data, which is necessary for any study of a static electron density distribution.