The crystal structure of caratiite

Abstract

The crystal structure of caratiite, K ₄Cu ₄O ₂ (SO ₄) ₄ MeCl ( a 13.60(2), c 4.98(1) Å, Z = 2) was solved in space group I4 from single crystal data, and refined to R = 0.035 for 654F _o > 6 σ(F _o). The atomic arrangement is characterized by Cu ₂O(SO ₄) ₂ chains parallel to [001], with Cu in (4 + 1) co-ordination and O surrounded tetrahedrally by four Cu atoms. These chains are interconnected by K atoms to a framework, the channels of which house the Me and Cl atoms. The nature of the Me atoms is not completely clear; most probably the position is half occupied by Cu, fully occupied by Na, or occupied by a mixture of the two.