The coordination polyhedra PrOn in the crystal structure

Abstract

The oxygen environment of the Pr atoms in the crystal structures of 235 complexes containing 331 crystallographically nonequivalent types of PrOn polyhedra was analyzed using Voronoi-Dirichlet (VD) polyhedra and the method of intersecting spheres. It was found that the C.Ns. of Pr(III) and Pr(IV) atoms coordinating O atoms vary from 5 to 12 and from 5 to 9, respectively. The volumes of the VD polyhedra increase, on average, by 1.2 A3 when going from Pr(IV) to Pr(III). For the same oxidation state of the Pr atom, the volume of its VD polyhedron remains virtually independent of the C.N., although the Pr-O bond length changes by 0.86 A in Pr(III) complexes and by 0.77 A in Pr(IV) complexes.