Redetermination of Hg2I2 (= moschelite) structure

[journals.iucr.org]

M. Kars, T. Roisnel, V. Dorcet, A. Rebbah and O.-D. L. Carlos (2012): Redetermination of Hg2I2. Acta Crystallogr. E68, i11.

The crystal structure of mercurous iodide, Hg2I2, has been determined previously from X-ray powder diffraction data [Havighurst (1926[Havighurst, R. J. (1926). J. Am. Chem. Soc. 48, 2113-2125.]). J. Am. Chem. Soc. 48, 2113-2125]. The results of the current redetermination based on single-crystal X-ray diffraction data provide more precise geometrical data and also anisotropic displacement parameters for the Hg and I atoms, which are both situated on positions with site-symmetry 4mm. The structure consists of linear dimers I-Hg-Hg-I extending along the c axis with an Hg-Hg distance of 2.5903 (13) Å. The overall coordination sphere of the Hg+ atom is a considerably distorted octahedron. The crystal specimen under investigation was twinned by non-merohedry with a refined twin domain fraction of 0.853 (14):0.147 (14)

Tetragonal, I 4/m m m
a = 4.8974 (9) Å
c = 11.649 (2) Å
V = 279.40 (9) Å3
Z = 2

Updated.