The crystal structures of ErSeI and NaErSe2

Article abstract of DOI:10.1002/zaac.19976231026

It is reported about attempts to synthesize lanthanoide selenidehalides of the formula LnSeX (X = Cl, Br, I) exemplary for Ln = Er. The relative stabilities of these compounds are discussed. X-ray crystal structure analysis revealed for the compounds ErSeBr and ErSeI the FeOCl-structure type (space group Pmmn, Z = 2, a = 406.3(5) pm, b = 559.2(6) pm, and c = 795(1) pm, and a = 418.26(6) pm, b = 558.4(1) pm. and c = 889.0(2) pm, respectively). A corresponding chloride was not found within the scope of this investigation. From the educts Er₂Se₃ and ErCl₃ in the presence of NaCl as flux in Nb-ampoules the compound NaErSe₂ was formed instead which crystallines in an α-NaFeO₂-type structure (space group R3?m, Z = 3, a = 408.41(2) pm and c = 2067.4(2) pm).