Redetermination of Zn2Mo3O8

Abstract

The crystal structure of dizinc trimolybdenum(IV) octaoxide, Zn 2Mo3O8, has been redetermined from single-crystal X-ray data. The structure has been reported previously based on neutron powder diffraction data [Hibble et al. (1999). Acta Cryst. B55, 683-697] and single-crystal data [McCarroll et al. (1957). J. Am. Chem. Soc. 79, 5410?5414; Ansell & Katz (1966) Acta Cryst. 21, 482?485]. The results of the current redetermination show an improvement in the precision of the structural and geometric parameters with all atoms refined with anisotropic displacement parameters. The crystal structure consists of distorted hexagonal-close-packed oxygen layers with stacking sequence abac along [001] and is held together by alternating zinc and molybdenum layers. The Zn atoms occupy both tetrahedral and octahedral interstices with a ratio of 1:1. The Mo atoms occupy octahedral sites and form strongly bonded triangular clusters involving three MoO 6 octahedra that are each shared along two edges, forming a Mo 3O13 unit. All atoms lie on special positions. The Zn atoms are in 2b Wyckoff positions with 3m. site symmetry, the Mo atoms are in 6c Wyckoff positions with . m. site symmetry and the O atoms are in 2a, 2b and 6c Wyckoff positions with 3m. and . m. site symmetries, respectively.