KCeSiS4 crystallizes in the monoclinic P2_1 space group. K(1) is bonded in a 8-coordinate geometry to one S(1), two equivalent S(3), two equivalent S(4), and three equivalent S(2) atoms. Ce(1) is bonded in a 7-coordinate geometry to one S(2), two equivalent S(1), two equivalent S(3), and two equivalent S(4) atoms. Si(1) is bonded in a tetrahedral geometry to one S(1), one S(2), one S(3), and one S(4) atom. There are four inequivalent S sites. In the first S site, S(1) is bonded in a distorted see-saw-like geometry to one K(1), two equivalent Ce(1), and one Si(1) atom. In the second S site, S(2) is bonded to three equivalent K(1), one Ce(1), and one Si(1) atom to form distorted SK3CeSi trigonal bipyramids that share corners with five equivalent S(4)K2Ce2Si square pyramids, corners with two equivalent S(2)K3CeSi trigonal bipyramids, edges with two equivalent S(4)K2Ce2Si square pyramids, and edges with two equivalent S(2)K3CeSi trigonal bipyramids. In the third S site, S(3) is bonded in a 5-coordinate geometry to two equivalent K(1), two equivalent Ce(1), and one Si(1) atom. In the fourth S site, S(4) is bonded to two equivalent K(1), two equivalent Ce(1), and one Si(1) atom to form distorted SK2Ce2Si square pyramids that share corners with four equivalent S(4)K2Ce2Si square pyramids, corners with five equivalent S(2)K3CeSi trigonal bipyramids, and edges with two equivalent S(2)K3CeSi trigonal bipyramids.
KCeSiS4 crystallizes in the monoclinic P2_1 space group. K(1) is bonded in a 8-coordinate geometry to one S(1), two equivalent S(3), two equivalent S(4), and three equivalent S(2) atoms. The K(1)-S(1) bond length is 3.31 Å. There is one shorter (3.30 Å) and one longer (3.53 Å) K(1)-S(3) bond length. There is one shorter (3.35 Å) and one longer (3.38 Å) K(1)-S(4) bond length. There are a spread of K(1)-S(2) bond distances ranging from 3.28-3.56 Å. Ce(1) is bonded in a 7-coordinate geometry to one S(2), two equivalent S(1), two equivalent S(3), and two equivalent S(4) atoms. The Ce(1)-S(2) bond length is 2.86 Å. There is one shorter (2.91 Å) and one longer (3.06 Å) Ce(1)-S(1) bond length. There is one shorter (2.92 Å) and one longer (2.94 Å) Ce(1)-S(3) bond length. There is one shorter (2.96 Å) and one longer (3.00 Å) Ce(1)-S(4) bond length. Si(1) is bonded in a tetrahedral geometry to one S(1), one S(2), one S(3), and one S(4) atom. The Si(1)-S(1) bond length is 2.13 Å. The Si(1)-S(2) bond length is 2.10 Å. The Si(1)-S(3) bond length is 2.12 Å. The Si(1)-S(4) bond length is 2.12 Å. There are four inequivalent S sites. In the first S site, S(1) is bonded in a distorted see-saw-like geometry to one K(1), two equivalent Ce(1), and one Si(1) atom. In the second S site, S(2) is bonded to three equivalent K(1), one Ce(1), and one Si(1) atom to form distorted SK3CeSi trigonal bipyramids that share corners with five equivalent S(4)K2Ce2Si square pyramids, corners with two equivalent S(2)K3CeSi trigonal bipyramids, edges with two equivalent S(4)K2Ce2Si square pyramids, and edges with two equivalent S(2)K3CeSi trigonal bipyramids. In the third S site, S(3) is bonded in a 5-coordinate geometry to two equivalent K(1), two equivalent Ce(1), and one Si(1) atom. In the fourth S site, S(4) is bonded to two equivalent K(1), two equivalent Ce(1), and one Si(1) atom to form distorted SK2Ce2Si square pyramids that share corners with four equivalent S(4)K2Ce2Si square pyramids, corners with five equivalent S(2)K3CeSi trigonal bipyramids, and edges with two equivalent S(2)K3CeSi trigonal bipyramids.