The Crystal Structures and Raman Spectra of Three New Hydrothermally Synthesized Copper–Zinc–Oxotellurates(IV)

Three new copper–zinc–tellurites, Zn4Cu(TeIVO3)4Cl2, Cu2Zn2(TeIVO3)2(SO4)(OH)2·H2O and Cu2Zn(TeIVO4)(SO4)·H2O (henceforth I, II and III), were synthesized under mild hydrothermal conditions (473 K, in Teflon-lined steel vessels). They were characterized in detail by a combination of crystal-structure determination (using single-crystal X-ray diffraction data), single-crystal micro-Raman spectroscopy and chemical analyses (energy-dispersive X-ray spectroscopy in a scanning electron microscope). Each compound crystallizes in a new structure type, and additionally, II and III represent the first two ever reported copper–zinc–tellurite–sulfates. I [systematic name: tetrazinc copper(II) tetrakis-oxotellurate(IV) dichloride] is triclinic, P1, and forms a framework structure based on ZnO6 and ZnO5Cl octahedra, linked into sheets connected via Jahn–Teller-distorted CuO4Cl2 octahedra, with TeIVO3 trigonal pyramids and TeIV2O6 dimers (composed of two edge-sharing TeIVO4 disphenoids) filling the remaining space. II [dicopper(II) dizinc bis-oxotellurate(IV) oxosulfate(VI) bis-hydroxide monohydrate] is trigonal, R3m, with a simonkolleite-like framework. Distinct layers formed from (Cu,Zn)φ6 (φ = O, OH) octahedra and TeIVO3 trigonal pyramids extend parallel to (001) and sandwich disordered SO42– anions and H2O groups. III [dicopper(II) zinc oxotellurate(IV) oxosulfate(VI) hydrate] is orthorhombic, Pnma, and also has a layered structure [extending parallel to (100)]. Positively charged layers of composition [Cu2ZnTeIVO4]2+ (containing Te as TeIVO4 disphenoids) alternate with SO42– anions and H2O groups in the interlayer space. Stacking disorder caused by the order-disorder nature of the crystal structure is reflected by the presence of residual electron density in difference-Fourier maps and the structure was refined as an overlay of two stacking possibilities.