New Crystal Structures of Rare‐Earth Metal(III) Oxotellurates(IV) RE2Te3O9: A1‐Type (RE=La, Ce) and A2‐Type (RE=Pr, Nd)

Abstract The new rare‐earth metal(III) oxotellurates(IV) RE2Te3O9 (RE=La−Nd) of the so far unknown A‐type structure can be obtained as needle‐shaped single crystals through solid‐state reactions of the corresponding binary oxides. Their crystal structures were determined as A1‐type for RE=La and Ce or A2‐type for RE=Pr and Nd by single‐crystal X‐ray diffraction. Both structure types crystallize in the monoclinic crystal system, but in two different non‐centrosymmetric space groups: the A1‐type with Z=8 in space group P21 (La2Te3O9: a=569.54(3), b=2230.12(13), c=1464.71(4) pm, β=101.205(3)°; Ce2Te3O9: a=567.02(3), b=2222.61(13), c=1457.13(9) pm, β=101.134(3)°) or the A2‐type with Z=16 in space group Cc (Pr2Te3O9: a=2838.61(16), b=563.89(3), c=2522.08(15) pm, β=118.816(3)°; Nd2Te3O9: a=2826.38(16), b=561.47(3), c=2511.94(15) pm, β=118.841(3)°). In spite of the differences in the unit‐cell parameters and the symmetry, both structures consist of quite similar fundamental building blocks (FBBs) consisting of eight crystallographically distinct rare‐earth metal‐oxygen polyhedra with C.N.(RE3+) from seven to nine and always twelve different ψ1‐tetrahedral oxotellurate(IV) anions [TeO3]2−, which show a high number of secondary bonding interactions (SBIs) with each other in all four cases.