Abstract

The crystal structure of the new mixed oxalate Y(H₂O)Cs(C₂O₄)₂ has been solved from powder X-ray diffraction data. The compound is isostructural with the related yttrium ammonium oxalate. It crystallises with monoclinic symmetry, a = 8.979(2), b = 6.2299(8), c = 8.103(1) Å, β = 90.05(2)° and V = 453.3 Å³, in space group P2/n. Its layered structure consists of corrugated planes of yttrium atoms linked by the oxalate groups, between which are intercalated the caesium atoms. The water molecule is connected to the yttrium atom and lies in the interlayer spacing. The thermal behaviour of the title compound has been characterised by means of temperature dependent X-ray diffraction (TDXD) and thermal analyses. Anhydrous yttrium caesium oxalate has been observed and isolated. Thermal decomposition of the mixed oxalate provides a new high-temperature orthorhombic modification of Cs₂CO₃.