CeSe2 is Cotunnite structured and crystallizes in the orthorhombic Pnma space group. Ce(1) is bonded in a 9-coordinate geometry to four equivalent Se(1) and five equivalent Se(2) atoms. There are two inequivalent Se sites. In the first Se site, Se(2) is bonded to five equivalent Ce(1) atoms to form distorted SeCe5 trigonal bipyramids that share corners with eight equivalent Se(1)Ce4 tetrahedra, corners with eight equivalent Se(2)Ce5 trigonal bipyramids, edges with six equivalent Se(1)Ce4 tetrahedra, and edges with six equivalent Se(2)Ce5 trigonal bipyramids. In the second Se site, Se(1) is bonded to four equivalent Ce(1) atoms to form distorted SeCe4 tetrahedra that share corners with eight equivalent Se(1)Ce4 tetrahedra, corners with eight equivalent Se(2)Ce5 trigonal bipyramids, edges with two equivalent Se(1)Ce4 tetrahedra, and edges with six equivalent Se(2)Ce5 trigonal bipyramids.
CeSe2 is Cotunnite structured and crystallizes in the orthorhombic Pnma space group. Ce(1) is bonded in a 9-coordinate geometry to four equivalent Se(1) and five equivalent Se(2) atoms. There are a spread of Ce(1)-Se(1) bond distances ranging from 2.89-2.98 Å. There are a spread of Ce(1)-Se(2) bond distances ranging from 3.06-3.27 Å. There are two inequivalent Se sites. In the first Se site, Se(2) is bonded to five equivalent Ce(1) atoms to form distorted SeCe5 trigonal bipyramids that share corners with eight equivalent Se(1)Ce4 tetrahedra, corners with eight equivalent Se(2)Ce5 trigonal bipyramids, edges with six equivalent Se(1)Ce4 tetrahedra, and edges with six equivalent Se(2)Ce5 trigonal bipyramids. In the second Se site, Se(1) is bonded to four equivalent Ce(1) atoms to form distorted SeCe4 tetrahedra that share corners with eight equivalent Se(1)Ce4 tetrahedra, corners with eight equivalent Se(2)Ce5 trigonal bipyramids, edges with two equivalent Se(1)Ce4 tetrahedra, and edges with six equivalent Se(2)Ce5 trigonal bipyramids.