Synthesis and structure of new layered copper oxide iodides, Sr2CuO2I2 and Sr2Cu3O4I2

Abstract

The first layered copper oxide iodides Sr₂CuO₂I₂ and Sr₂Cu₃O₄I₂ have been synthesised by reaction of SrO, SrI₂ and CuO in evacuated silica ampoules. Sr₂CuO₂I₂ crystallises with a K₂NiF₄-type structure and contains infinite CuO₂ planes separated by double SrI rocksalt layers. Sr₂Cu₃O₄I₂ contains sheets of Cu₃O₄ stoichiometry separated by fluorite Sr₂I₂ layers. Incorporation of the iodide ion results in an in-plane Cu–O bond distance of 2.015 Å in Sr₂CuO₂I₂ whilst the two distinct copper sites in Sr₂Cu₃O₄I₂possess near identical in-plane Cu–O interactions ≈1.96 Å.