Acta Crystallographica Section B

Structural Science

Volume 52, Part 3 (June 1996)

research papers

Acta Cryst. (1996). B52, 471-478 [ doi:10.1107/S0108768195016879 ]

Theoretical and experimental (113 K) electron-density study of lithium bis(tetramethylammonium) hexanitrocobaltate(III)

R. Bianchi, C. Gatti, V. Adovasio and M. Nardelli

Abstract: This paper presents an analysis of the crystal structure and the charge density, (r), for lithium bis(tetramethylammonium) hexanitrocobaltate(III) determined by the rigid pseudoatom model from accurate X-ray data measured at 113 K. This compound has also been investigated by an ab initio Hartree-Fock fully periodic approach. A comparison of the topological properties between the experimentally and theoretically derived density is also given. A notable agreement between experiment and theory is observed in the topological properties of the metal-ligand interaction and a close parallel between the orbital model description and the shape of the Laplacian distribution around the Co atom is outlined. The results confirm the typical 3d-electron distribution of octahedral Co^III complexes in a low-spin state and the presence of four C-HO hydrogen bonds in the crystal structure. Important differences between experiment and theory remain for the Laplacian and the parallel curvature (₃) values at the C-N and N-O bond critical points. The atomic charges derived from the Quantum Theory of Atoms in Molecules are remarkably close to the formal values.