‘Face-to-Face’ Relationships Between Oxocentred Tetrahedra and Cation-Centred Tetrahedral Oxyanions in Crystal Structures of Minerals and Inorganic Compounds

S. V. Krivovichev, G. L. Starova and S. K. Filatov
Department of Crystallography, St. Petersburg State University, University Emb. 7/9, 199034 St. Petersburg, Russia

Abstract: Detailed analysis of the crystal structures of minerals and inorganic compounds containing oxocentred [OCu4] tetrahedra reveals the following principle for relationships between oxocentred tetrahedra and tetrahedral oxyanions (Tn+O4)−(8−n) with T = S6+ or V5+, or triangular pyramidal oxyanions (SeO3)2− (which may be considered as (SeO3E)2− tetrahedra assuming the lone pair E of selenium to be a fourth ligand): (Tn+O4)−(8−n) tetrahedra are ‘attached’ to the oxocentred tetrahedra so that their grounds (O-O-O and Cu-Cu-Cu) are parallel to each other and the mutual orientation is regular (O corners are exactly under Cu corners). We propose to describe these relationships as ‘face-to-face’, meaning that the oxocentred and cation-centred tetrahedra ‘meet’ along their ‘whole’ triangular faces. Geometric characteristics of ‘face-to-face’ relationships are discussed.

Keywords: oxocentred tetrahedra • cation-centred tetrahedra • oxyanions • crystal structure

Mineralogical Magazine; April 1999 v. 63; no. 2; p. 263-266; DOI: 10.1180/002646199548376
© 1999, The Mineralogical Society
Mineralogical Society (www.minersoc.org)