Pr2SeO2 crystallizes in the trigonal P-3m1 space group. Pr(1) is bonded in a 7-coordinate geometry to three equivalent Se(1) and four equivalent O(1) atoms. Se(1) is bonded to six equivalent Pr(1) atoms to form SePr6 octahedra that share corners with twelve equivalent O(1)Pr4 tetrahedra, edges with six equivalent Se(1)Pr6 octahedra, and edges with six equivalent O(1)Pr4 tetrahedra. O(1) is bonded to four equivalent Pr(1) atoms to form OPr4 tetrahedra that share corners with six equivalent Se(1)Pr6 octahedra, corners with six equivalent O(1)Pr4 tetrahedra, edges with three equivalent Se(1)Pr6 octahedra, and edges with three equivalent O(1)Pr4 tetrahedra. The corner-sharing octahedral tilt angles range from 27-49°.
Pr2SeO2 crystallizes in the trigonal P-3m1 space group. Pr(1) is bonded in a 7-coordinate geometry to three equivalent Se(1) and four equivalent O(1) atoms. All Pr(1)-Se(1) bond lengths are 3.10 Å. There is one shorter (2.40 Å) and three longer (2.41 Å) Pr(1)-O(1) bond lengths. Se(1) is bonded to six equivalent Pr(1) atoms to form SePr6 octahedra that share corners with twelve equivalent O(1)Pr4 tetrahedra, edges with six equivalent Se(1)Pr6 octahedra, and edges with six equivalent O(1)Pr4 tetrahedra. O(1) is bonded to four equivalent Pr(1) atoms to form OPr4 tetrahedra that share corners with six equivalent Se(1)Pr6 octahedra, corners with six equivalent O(1)Pr4 tetrahedra, edges with three equivalent Se(1)Pr6 octahedra, and edges with three equivalent O(1)Pr4 tetrahedra. The corner-sharing octahedral tilt angles range from 27-49°.