Synthesis and crystal structure of Li 2[(UO 2)(MoO 4) 2], a uranyl molybdate with chains of corner-sharing uranyl square bipyramids and MoO 4 tetrahedra

Abstract

Crystals of Li 2[(UO 2)(MoO 4) 2] have been synthesized by solid-state reaction of Li 2CO 3, UO 3 and MoO 3. The crystal structure of the compound (triclinic, P1 , a=5.3455(4), b=5.8297(4), c=8.2652(6) Å, α=108.267(2), β=100.566(2), γ=104.121(2)°, V=227.56(3) Å 3, Z=1) has been solved by direct methods and refined to R 1=0.027 ( wR 2=0.047). The structure is based upon chains of composition [(UO 2)(MoO 4) 2] 2− composed of UrO 4 square bipyramids that share corners with MoO 4 tetrahedra. The chains are parallel to the a axis and are linked into a three-dimensional framework by Li + cations in trigonal bipyramidal coordination. The LiO 5 trigonal bipyramids form edge-sharing chains parallel to the a axis.