A NEW POLYMERIC ANTIMONY(III) OXOALKOXIDE, [SR2SB4O(OET)(14)](N) - THE SYNTHESIS AND MOLECULAR-STRUCTURE

A new bimetallic oxoalkoxide, with composition Sr2Sb4O(OEt)14, has been synthesized by reacting Sr(OEt)2 with an excess of Sb(OEt)3 in toluene-ethanol under a dry nitrogen atmosphere. Colorless transparent crystals of the alkoxide have been studied by single crystal X-ray diffraction methods. The crystals have a monoclinic space group symmetry P 21/n, with a = 11.609(3) Å, b = 22.006(5) Å, c = 18.948(5) Å, β = 105.08(2)°, V = 4673(2) Å3, Z = 4, Dx = 1.861(1) g · cm-3 and Mr = 1309.1. From the X-ray diffraction data collected at 163(1) K, refinements of the derived structure model against the amplitudes of the 3745 most significant reflections converged at an R-value of 0.043. The crystal structure consists of infinite parallel chains extending in the [100] direction. The polymer chains are formed by units of composition [Sr2Sb3O(OEt)10]+, that are linked by [Sb(OEt)4]- groups through pairs of bridging ethoxy oxygen atoms. The parallel chains are approximately close packed. The oxygen coordination polyhedra around two five-coordinated antimony atoms share a common face. The Sr atoms are seven-coordinated by oxygen atoms. As all the ethoxy oxygen atoms are two-coordinated and the oxo oxygen four coordinated by the metal ions, the formula of the present strontium-antimony oxoethoxide can be written [Sr2Sb4(μ4-O) (μ-OEt)14]n. © 1994 Academic Press, Inc.