UPr2Se4 crystallizes in the tetragonal I-42d space group. U(1) is bonded to eight equivalent Se(1) atoms to form distorted USe8 hexagonal bipyramids that share corners with eight equivalent Pr(1)Se8 hexagonal bipyramids, edges with four equivalent U(1)Se8 hexagonal bipyramids, and faces with eight equivalent Pr(1)Se8 hexagonal bipyramids. Pr(1) is bonded to eight equivalent Se(1) atoms to form distorted PrSe8 hexagonal bipyramids that share corners with four equivalent U(1)Se8 hexagonal bipyramids, corners with four equivalent Pr(1)Se8 hexagonal bipyramids, edges with four equivalent Pr(1)Se8 hexagonal bipyramids, faces with four equivalent U(1)Se8 hexagonal bipyramids, and faces with four equivalent Pr(1)Se8 hexagonal bipyramids. Se(1) is bonded to two equivalent U(1) and four equivalent Pr(1) atoms to form a mixture of distorted corner, edge, and face-sharing SePr4U2 octahedra. The corner-sharing octahedral tilt angles range from 15-50°.
UPr2Se4 crystallizes in the tetragonal I-42d space group. U(1) is bonded to eight equivalent Se(1) atoms to form distorted USe8 hexagonal bipyramids that share corners with eight equivalent Pr(1)Se8 hexagonal bipyramids, edges with four equivalent U(1)Se8 hexagonal bipyramids, and faces with eight equivalent Pr(1)Se8 hexagonal bipyramids. There are four shorter (2.99 Å) and four longer (3.12 Å) U(1)-Se(1) bond lengths. Pr(1) is bonded to eight equivalent Se(1) atoms to form distorted PrSe8 hexagonal bipyramids that share corners with four equivalent U(1)Se8 hexagonal bipyramids, corners with four equivalent Pr(1)Se8 hexagonal bipyramids, edges with four equivalent Pr(1)Se8 hexagonal bipyramids, faces with four equivalent U(1)Se8 hexagonal bipyramids, and faces with four equivalent Pr(1)Se8 hexagonal bipyramids. There are a spread of Pr(1)-Se(1) bond distances ranging from 3.02-3.19 Å. Se(1) is bonded to two equivalent U(1) and four equivalent Pr(1) atoms to form a mixture of distorted corner, edge, and face-sharing SePr4U2 octahedra. The corner-sharing octahedral tilt angles range from 15-50°.