Sr[ReO4]2 : the first single crystals of an anhydrous alkaline‐earth metal meta‐perrhenate

Abstract

Colorless single crystals of Sr[ReO4]2 were obtained from halide melts at 1123 K in open corundum crucibles. X‐ray diffraction revealed that Sr[ReO4]2 crystallizes in the monoclinic space group P21/n with the lattice parameters a = 627.31(4) pm, b = 1004.56(7) pm, c = 1271.25(9) pm and β = 97.118(3)° for Z = 4. The crystal structure contains a unique Sr2+‐cation site surrounded by eight crystallographically different oxygen atoms forming distorted bicapped trigonal prisms. All corners of these [SrO8]14- polyhedra (d(Sr-O) = 259-268 pm) are shared with tetrahedral meta‐perrhenate units [ReO4]- (d(Re-O) = 166-173 pm) formed from two crystallographically different Re7+ cations surrounded by four O2- anions each, building up the three‐dimensional mosaic‐like structure of Sr[ReO4]2. Single‐crystal Raman data confirm the presence of two different kinds of symmetry‐free meta‐perrhenate units [ReO4]- and match well with results known from literature.