Hydrothermal synthesis and crystal structure of ErSeO3Cl

A new erbium-selenium oxychloride, ErSeO3Cl, has been synthesized hydrothermally starting from ErCl3·6H2O and SeO2 in LiCl aqueous solution, and its crystal structure solved from single-crystal X-ray diffraction data. ErSeO3Cl crystallizes in the HoTeO3Cl structure type in the orthorhombic system, space group Pnma (No. 62), with the cell parameters a=7.185(1) A, b=6.890(1) A, c=8.720(2) A, V=431.7(1) A3, Z=4. The structure was refined to R1=0.0259, wR2=0.0648 for 35 variables and 508 unique reflections. The 3D structure of ErSeO3Cl is formed from linked ErO5Cl2 polyhedra and SeO3E (E--lone electron pair) polyhedra. We compare the crystal structure of ErSeO3Cl with the structures of other known rare-earth (Bi)-Se(Te) oxyhalides of the common formula MChO3X (M=Ln(Bi), Ch=Se, Te, X=Cl, Br, I)