title: Crystal structure of Sr5Te4O12(OH)2, the first basic strontium oxotellurate(IV).
abstract: The asymmetric unit of the title basic strontium oxotellurate(IV), Sr5Te4O12(OH)2{systematic name penta-strontium tetra-kis-[oxotellurate(IV)] di-hydroxide}, comprises three SrIIcations (one with site symmetry 2) and two TeIVatoms, as well as seven O atoms. The coordination numbers of the alkaline earth cations to nearby O atoms range from seven (2 ×) to eight, and the TeIVatoms are surrounded by three oxygen partners in the form of trigonal pyramids. The SrOxpolyhedra share corners and edges to build up a three-dimensional framework structure encapsulating channels propagating along [010]. The TeIVatoms flank the framework O atoms and are situated at the outer array of the channels with the 5s2lone electron pairs protruding into the empty space of the channels (diameter ≃ 4 Å). Although the H atom of the OH group could not be located, bond-valence-sum calculations and typical O⋯O distances (range 2.81-3.06 Å) clearly indicate hydrogen bonding of medium to weak strengths.
authors.affiliation: Institute for Chemical Technologies and Analytics, Division of Structural Chemistry, Vienna University of Technology, Getreidemarkt 9/164-SC, A-1060 Vienna, Austria.
authors.forename: Matthias
authors.initials: M
authors.lastname: Weil
authors.affiliation: Institute for Chemical Technologies and Analytics, Division of Structural Chemistry, Vienna University of Technology, Getreidemarkt 9/164-SC, A-1060 Vienna, Austria.
authors.forename: Mahdi
authors.initials: M
authors.lastname: Shirkhanlou
keywords: channel structure; crystal structure; stereoactive electron lone pair; strontium tellurite