Ca₂CuO₂Cl₂, a redetermination from single-crystal X-ray diffraction data

The crystal structure of Ca2CuO2Cl2, dicalcium oxidocuprate(II) dichloride, was redetermined on the basis of single-crystal X-ray diffraction data using a laboratory Mo anode. Previous structure determinations based on single-crystal X-ray data [Grande & Müller-Buschbaum (1977). Z. Anorg. Allg. Chem. 429, 88–90], powder X-ray diffraction data [Yamada et al. (2005). Phys. Rev. B, 72, 224503–1–5] or neutron diffraction data [Argyriou et al. (1995). Phys. Rev. B, 51, 8434–8437] were confirmed. The present study allowed the refinement of anisotropic displacement parameters for all crystallographic sites, accompanied with higher accuracy and precision for bond lengths and angles. The layered title compound comprises of [CuO4] square-planar and [CaO4Cl4] square-antiprismatic coordination polyhedra, and is the undoped parent compound of a high-temperature superconducting cuprate.