BaCe(SnSe3)2 crystallizes in the orthorhombic Pmc2_1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 9-coordinate geometry to one Se(4), two equivalent Se(1), two equivalent Se(5), two equivalent Se(6), and two equivalent Se(7) atoms. In the second Ba site, Ba(2) is bonded in a distorted q6 geometry to one Se(3), two equivalent Se(10), two equivalent Se(11), two equivalent Se(8), and two equivalent Se(9) atoms. There are two inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 8-coordinate geometry to one Se(1), one Se(2), two equivalent Se(5), two equivalent Se(6), and two equivalent Se(8) atoms. In the second Ce site, Ce(2) is bonded in a 8-coordinate geometry to one Se(4), two equivalent Se(10), two equivalent Se(11), two equivalent Se(12), and two equivalent Se(3) atoms. There are four inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to one Se(2), two equivalent Se(7), and two equivalent Se(9) atoms to form distorted SnSe5 square pyramids that share corners with two equivalent Sn(4)Se5 trigonal bipyramids, edges with two equivalent Sn(2)Se6 octahedra, and edges with two equivalent Sn(1)Se5 square pyramids. In the second Sn site, Sn(2) is bonded to one Se(5), one Se(7), two equivalent Se(1), and two equivalent Se(2) atoms to form SnSe6 octahedra that share edges with two equivalent Sn(2)Se6 octahedra and edges with two equivalent Sn(1)Se5 square pyramids. In the third Sn site, Sn(3) is bonded to one Se(10), one Se(6), one Se(8), and two equivalent Se(4) atoms to form corner-sharing SnSe5 trigonal bipyramids. In the fourth Sn site, Sn(4) is bonded to one Se(11), one Se(12), one Se(9), and two equivalent Se(3) atoms to form corner-sharing SnSe5 trigonal bipyramids. There are twelve inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent Ba(1), one Ce(1), and two equivalent Sn(2) atoms to form SeBa2CeSn2 trigonal bipyramids that share corners with two equivalent Se(6)Ba2Ce2Sn square pyramids, corners with two equivalent Se(8)Ba2Ce2Sn square pyramids, corners with two equivalent Se(7)Ba2Sn3 square pyramids, corners with four equivalent Se(1)Ba2CeSn2 trigonal bipyramids, edges with two equivalent Se(6)Ba2Ce2Sn square pyramids, edges with two equivalent Se(7)Ba2Sn3 square pyramids, and edges with four equivalent Se(5)Ba2Ce2Sn square pyramids. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to one Ce(1), one Sn(1), and two equivalent Sn(2) atoms. In the third Se site, Se(3) is bonded in a 5-coordinate geometry to one Ba(2), two equivalent Ce(2), and two equivalent Sn(4) atoms. In the fourth Se site, Se(4) is bonded in a 3-coordinate geometry to one Ba(1), one Ce(2), and two equivalent Sn(3) atoms. In the fifth Se site, Se(5) is bonded to two equivalent Ba(1), two equivalent Ce(1), and one Sn(2) atom to form distorted SeBa2Ce2Sn square pyramids that share corners with two equivalent Se(8)Ba2Ce2Sn square pyramids, corners with three equivalent Se(7)Ba2Sn3 square pyramids, corners with four equivalent Se(6)Ba2Ce2Sn square pyramids,  an edgeedge with one Se(8)Ba2Ce2Sn square pyramid,  an edgeedge with one Se(7)Ba2Sn3 square pyramid, edges with two equivalent Se(5)Ba2Ce2Sn square pyramids, edges with two equivalent Se(6)Ba2Ce2Sn square pyramids, and edges with four equivalent Se(1)Ba2CeSn2 trigonal bipyramids. In the sixth Se site, Se(6) is bonded to two equivalent Ba(1), two equivalent Ce(1), and one Sn(3) atom to form SeBa2Ce2Sn square pyramids that share  a cornercorner with one Se(10)Ba2Ce2Sn square pyramid, corners with two equivalent Se(8)Ba2Ce2Sn square pyramids, corners with two equivalent Se(7)Ba2Sn3 square pyramids, corners with four equivalent Se(5)Ba2Ce2Sn square pyramids, corners with two equivalent Se(1)Ba2CeSn2 trigonal bipyramids,  an edgeedge with one Se(7)Ba2Sn3 square pyramid, edges with two equivalent Se(5)Ba2Ce2Sn square pyramids, edges with two equivalent Se(6)Ba2Ce2Sn square pyramids, edges with two equivalent Se(1)Ba2CeSn2 trigonal bipyramids, and  a faceface with one Se(8)Ba2Ce2Sn square pyramid. In the seventh Se site, Se(7) is bonded to two equivalent Ba(1), one Sn(2), and two equivalent Sn(1) atoms to form SeBa2Sn3 square pyramids that share corners with two equivalent Se(6)Ba2Ce2Sn square pyramids, corners with two equivalent Se(9)Ba2Sn3 square pyramids, corners with three equivalent Se(5)Ba2Ce2Sn square pyramids, corners with two equivalent Se(1)Ba2CeSn2 trigonal bipyramids,  an edgeedge with one Se(5)Ba2Ce2Sn square pyramid,  an edgeedge with one Se(6)Ba2Ce2Sn square pyramid,  an edgeedge with one Se(9)Ba2Sn3 square pyramid, edges with two equivalent Se(7)Ba2Sn3 square pyramids, and edges with two equivalent Se(1)Ba2CeSn2 trigonal bipyramids. In the eighth Se site, Se(8) is bonded to two equivalent Ba(2), two equivalent Ce(1), and one Sn(3) atom to form SeBa2Ce2Sn square pyramids that share corners with two equivalent Se(10)Ba2Ce2Sn square pyramids, corners with two equivalent Se(11)Ba2Ce2Sn square pyramids, corners with two equivalent Se(5)Ba2Ce2Sn square pyramids, corners with two equivalent Se(6)Ba2Ce2Sn square pyramids, corners with two equivalent Se(9)Ba2Sn3 square pyramids, corners with two equivalent Se(1)Ba2CeSn2 trigonal bipyramids,  an edgeedge with one Se(11)Ba2Ce2Sn square pyramid,  an edgeedge with one Se(5)Ba2Ce2Sn square pyramid,  an edgeedge with one Se(9)Ba2Sn3 square pyramid, edges with two equivalent Se(8)Ba2Ce2Sn square pyramids,  a faceface with one Se(10)Ba2Ce2Sn square pyramid, and  a faceface with one Se(6)Ba2Ce2Sn square pyramid. In the ninth Se site, Se(9) is bonded to two equivalent Ba(2), one Sn(4), and two equivalent Sn(1) atoms to form SeBa2Sn3 square pyramids that share corners with two equivalent Se(10)Ba2Ce2Sn square pyramids, corners with two equivalent Se(11)Ba2Ce2Sn square pyramids, corners with two equivalent Se(8)Ba2Ce2Sn square pyramids, corners with two equivalent Se(7)Ba2Sn3 square pyramids,  an edgeedge with one Se(10)Ba2Ce2Sn square pyramid,  an edgeedge with one Se(8)Ba2Ce2Sn square pyramid,  an edgeedge with one Se(7)Ba2Sn3 square pyramid, edges with two equivalent Se(9)Ba2Sn3 square pyramids, and  a faceface with one Se(11)Ba2Ce2Sn square pyramid. In the tenth Se site, Se(10) is bonded to two equivalent Ba(2), two equivalent Ce(2), and one Sn(3) atom to form SeBa2Ce2Sn square pyramids that share  a cornercorner with one Se(6)Ba2Ce2Sn square pyramid, corners with two equivalent Se(8)Ba2Ce2Sn square pyramids, corners with two equivalent Se(9)Ba2Sn3 square pyramids, corners with four equivalent Se(11)Ba2Ce2Sn square pyramids,  an edgeedge with one Se(9)Ba2Sn3 square pyramid, edges with two equivalent Se(10)Ba2Ce2Sn square pyramids, edges with two equivalent Se(11)Ba2Ce2Sn square pyramids, and  a faceface with one Se(8)Ba2Ce2Sn square pyramid. In the eleventh Se site, Se(11) is bonded to two equivalent Ba(2), two equivalent Ce(2), and one Sn(4) atom to form SeBa2Ce2Sn square pyramids that share corners with two equivalent Se(8)Ba2Ce2Sn square pyramids, corners with two equivalent Se(9)Ba2Sn3 square pyramids, corners with four equivalent Se(10)Ba2Ce2Sn square pyramids,  an edgeedge with one Se(8)Ba2Ce2Sn square pyramid, edges with two equivalent Se(10)Ba2Ce2Sn square pyramids, edges with two equivalent Se(11)Ba2Ce2Sn square pyramids, and  a faceface with one Se(9)Ba2Sn3 square pyramid. In the twelfth Se site, Se(12) is bonded in a trigonal non-coplanar geometry to two equivalent Ce(2) and one Sn(4) atom.
BaCe(SnSe3)2 crystallizes in the orthorhombic Pmc2_1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 9-coordinate geometry to one Se(4), two equivalent Se(1), two equivalent Se(5), two equivalent Se(6), and two equivalent Se(7) atoms. The Ba(1)-Se(4) bond length is 3.81 Å. There is one shorter (3.44 Å) and one longer (3.62 Å) Ba(1)-Se(1) bond length. Both Ba(1)-Se(5) bond lengths are 3.29 Å. Both Ba(1)-Se(6) bond lengths are 3.28 Å. Both Ba(1)-Se(7) bond lengths are 3.29 Å. In the second Ba site, Ba(2) is bonded in a distorted q6 geometry to one Se(3), two equivalent Se(10), two equivalent Se(11), two equivalent Se(8), and two equivalent Se(9) atoms. The Ba(2)-Se(3) bond length is 3.56 Å. Both Ba(2)-Se(10) bond lengths are 3.47 Å. Both Ba(2)-Se(11) bond lengths are 3.41 Å. Both Ba(2)-Se(8) bond lengths are 3.46 Å. Both Ba(2)-Se(9) bond lengths are 3.41 Å. There are two inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 8-coordinate geometry to one Se(1), one Se(2), two equivalent Se(5), two equivalent Se(6), and two equivalent Se(8) atoms. The Ce(1)-Se(1) bond length is 3.07 Å. The Ce(1)-Se(2) bond length is 3.11 Å. Both Ce(1)-Se(5) bond lengths are 2.97 Å. Both Ce(1)-Se(6) bond lengths are 3.08 Å. Both Ce(1)-Se(8) bond lengths are 3.15 Å. In the second Ce site, Ce(2) is bonded in a 8-coordinate geometry to one Se(4), two equivalent Se(10), two equivalent Se(11), two equivalent Se(12), and two equivalent Se(3) atoms. The Ce(2)-Se(4) bond length is 3.21 Å. Both Ce(2)-Se(10) bond lengths are 3.07 Å. Both Ce(2)-Se(11) bond lengths are 3.04 Å. Both Ce(2)-Se(12) bond lengths are 3.00 Å. There is one shorter (3.24 Å) and one longer (3.87 Å) Ce(2)-Se(3) bond length. There are four inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to one Se(2), two equivalent Se(7), and two equivalent Se(9) atoms to form distorted SnSe5 square pyramids that share corners with two equivalent Sn(4)Se5 trigonal bipyramids, edges with two equivalent Sn(2)Se6 octahedra, and edges with two equivalent Sn(1)Se5 square pyramids. The Sn(1)-Se(2) bond length is 2.90 Å. Both Sn(1)-Se(7) bond lengths are 2.96 Å. Both Sn(1)-Se(9) bond lengths are 3.11 Å. In the second Sn site, Sn(2) is bonded to one Se(5), one Se(7), two equivalent Se(1), and two equivalent Se(2) atoms to form SnSe6 octahedra that share edges with two equivalent Sn(2)Se6 octahedra and edges with two equivalent Sn(1)Se5 square pyramids. The Sn(2)-Se(5) bond length is 2.80 Å. The Sn(2)-Se(7) bond length is 2.74 Å. Both Sn(2)-Se(1) bond lengths are 2.83 Å. Both Sn(2)-Se(2) bond lengths are 2.85 Å. In the third Sn site, Sn(3) is bonded to one Se(10), one Se(6), one Se(8), and two equivalent Se(4) atoms to form corner-sharing SnSe5 trigonal bipyramids. The Sn(3)-Se(10) bond length is 2.73 Å. The Sn(3)-Se(6) bond length is 2.69 Å. The Sn(3)-Se(8) bond length is 2.66 Å. Both Sn(3)-Se(4) bond lengths are 2.68 Å. In the fourth Sn site, Sn(4) is bonded to one Se(11), one Se(12), one Se(9), and two equivalent Se(3) atoms to form corner-sharing SnSe5 trigonal bipyramids. The Sn(4)-Se(11) bond length is 2.77 Å. The Sn(4)-Se(12) bond length is 2.75 Å. The Sn(4)-Se(9) bond length is 2.59 Å. Both Sn(4)-Se(3) bond lengths are 2.67 Å. There are twelve inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent Ba(1), one Ce(1), and two equivalent Sn(2) atoms to form SeBa2CeSn2 trigonal bipyramids that share corners with two equivalent Se(6)Ba2Ce2Sn square pyramids, corners with two equivalent Se(8)Ba2Ce2Sn square pyramids, corners with two equivalent Se(7)Ba2Sn3 square pyramids, corners with four equivalent Se(1)Ba2CeSn2 trigonal bipyramids, edges with two equivalent Se(6)Ba2Ce2Sn square pyramids, edges with two equivalent Se(7)Ba2Sn3 square pyramids, and edges with four equivalent Se(5)Ba2Ce2Sn square pyramids. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to one Ce(1), one Sn(1), and two equivalent Sn(2) atoms. In the third Se site, Se(3) is bonded in a 5-coordinate geometry to one Ba(2), two equivalent Ce(2), and two equivalent Sn(4) atoms. In the fourth Se site, Se(4) is bonded in a 3-coordinate geometry to one Ba(1), one Ce(2), and two equivalent Sn(3) atoms. In the fifth Se site, Se(5) is bonded to two equivalent Ba(1), two equivalent Ce(1), and one Sn(2) atom to form distorted SeBa2Ce2Sn square pyramids that share corners with two equivalent Se(8)Ba2Ce2Sn square pyramids, corners with three equivalent Se(7)Ba2Sn3 square pyramids, corners with four equivalent Se(6)Ba2Ce2Sn square pyramids,  an edgeedge with one Se(8)Ba2Ce2Sn square pyramid,  an edgeedge with one Se(7)Ba2Sn3 square pyramid, edges with two equivalent Se(5)Ba2Ce2Sn square pyramids, edges with two equivalent Se(6)Ba2Ce2Sn square pyramids, and edges with four equivalent Se(1)Ba2CeSn2 trigonal bipyramids. In the sixth Se site, Se(6) is bonded to two equivalent Ba(1), two equivalent Ce(1), and one Sn(3) atom to form SeBa2Ce2Sn square pyramids that share  a cornercorner with one Se(10)Ba2Ce2Sn square pyramid, corners with two equivalent Se(8)Ba2Ce2Sn square pyramids, corners with two equivalent Se(7)Ba2Sn3 square pyramids, corners with four equivalent Se(5)Ba2Ce2Sn square pyramids, corners with two equivalent Se(1)Ba2CeSn2 trigonal bipyramids,  an edgeedge with one Se(7)Ba2Sn3 square pyramid, edges with two equivalent Se(5)Ba2Ce2Sn square pyramids, edges with two equivalent Se(6)Ba2Ce2Sn square pyramids, edges with two equivalent Se(1)Ba2CeSn2 trigonal bipyramids, and  a faceface with one Se(8)Ba2Ce2Sn square pyramid. In the seventh Se site, Se(7) is bonded to two equivalent Ba(1), one Sn(2), and two equivalent Sn(1) atoms to form SeBa2Sn3 square pyramids that share corners with two equivalent Se(6)Ba2Ce2Sn square pyramids, corners with two equivalent Se(9)Ba2Sn3 square pyramids, corners with three equivalent Se(5)Ba2Ce2Sn square pyramids, corners with two equivalent Se(1)Ba2CeSn2 trigonal bipyramids,  an edgeedge with one Se(5)Ba2Ce2Sn square pyramid,  an edgeedge with one Se(6)Ba2Ce2Sn square pyramid,  an edgeedge with one Se(9)Ba2Sn3 square pyramid, edges with two equivalent Se(7)Ba2Sn3 square pyramids, and edges with two equivalent Se(1)Ba2CeSn2 trigonal bipyramids. In the eighth Se site, Se(8) is bonded to two equivalent Ba(2), two equivalent Ce(1), and one Sn(3) atom to form SeBa2Ce2Sn square pyramids that share corners with two equivalent Se(10)Ba2Ce2Sn square pyramids, corners with two equivalent Se(11)Ba2Ce2Sn square pyramids, corners with two equivalent Se(5)Ba2Ce2Sn square pyramids, corners with two equivalent Se(6)Ba2Ce2Sn square pyramids, corners with two equivalent Se(9)Ba2Sn3 square pyramids, corners with two equivalent Se(1)Ba2CeSn2 trigonal bipyramids,  an edgeedge with one Se(11)Ba2Ce2Sn square pyramid,  an edgeedge with one Se(5)Ba2Ce2Sn square pyramid,  an edgeedge with one Se(9)Ba2Sn3 square pyramid, edges with two equivalent Se(8)Ba2Ce2Sn square pyramids,  a faceface with one Se(10)Ba2Ce2Sn square pyramid, and  a faceface with one Se(6)Ba2Ce2Sn square pyramid. In the ninth Se site, Se(9) is bonded to two equivalent Ba(2), one Sn(4), and two equivalent Sn(1) atoms to form SeBa2Sn3 square pyramids that share corners with two equivalent Se(10)Ba2Ce2Sn square pyramids, corners with two equivalent Se(11)Ba2Ce2Sn square pyramids, corners with two equivalent Se(8)Ba2Ce2Sn square pyramids, corners with two equivalent Se(7)Ba2Sn3 square pyramids,  an edgeedge with one Se(10)Ba2Ce2Sn square pyramid,  an edgeedge with one Se(8)Ba2Ce2Sn square pyramid,  an edgeedge with one Se(7)Ba2Sn3 square pyramid, edges with two equivalent Se(9)Ba2Sn3 square pyramids, and  a faceface with one Se(11)Ba2Ce2Sn square pyramid. In the tenth Se site, Se(10) is bonded to two equivalent Ba(2), two equivalent Ce(2), and one Sn(3) atom to form SeBa2Ce2Sn square pyramids that share  a cornercorner with one Se(6)Ba2Ce2Sn square pyramid, corners with two equivalent Se(8)Ba2Ce2Sn square pyramids, corners with two equivalent Se(9)Ba2Sn3 square pyramids, corners with four equivalent Se(11)Ba2Ce2Sn square pyramids,  an edgeedge with one Se(9)Ba2Sn3 square pyramid, edges with two equivalent Se(10)Ba2Ce2Sn square pyramids, edges with two equivalent Se(11)Ba2Ce2Sn square pyramids, and  a faceface with one Se(8)Ba2Ce2Sn square pyramid. In the eleventh Se site, Se(11) is bonded to two equivalent Ba(2), two equivalent Ce(2), and one Sn(4) atom to form SeBa2Ce2Sn square pyramids that share corners with two equivalent Se(8)Ba2Ce2Sn square pyramids, corners with two equivalent Se(9)Ba2Sn3 square pyramids, corners with four equivalent Se(10)Ba2Ce2Sn square pyramids,  an edgeedge with one Se(8)Ba2Ce2Sn square pyramid, edges with two equivalent Se(10)Ba2Ce2Sn square pyramids, edges with two equivalent Se(11)Ba2Ce2Sn square pyramids, and  a faceface with one Se(9)Ba2Sn3 square pyramid. In the twelfth Se site, Se(12) is bonded in a trigonal non-coplanar geometry to two equivalent Ce(2) and one Sn(4) atom.