Ba6(BiSe2)13 crystallizes in the monoclinic Pm space group. There are six inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to one Se(17), one Se(7), two equivalent Se(14), two equivalent Se(22), and two equivalent Se(26) atoms. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one Se(18), one Se(8), two equivalent Se(13), two equivalent Se(21), and two equivalent Se(25) atoms. In the third Ba site, Ba(3) is bonded in a 8-coordinate geometry to one Se(1), one Se(3), two equivalent Se(10), two equivalent Se(20), and two equivalent Se(6) atoms. In the fourth Ba site, Ba(4) is bonded in a 8-coordinate geometry to one Se(2), one Se(4), two equivalent Se(19), two equivalent Se(5), and two equivalent Se(9) atoms. In the fifth Ba site, Ba(5) is bonded in a 9-coordinate geometry to one Se(1), one Se(23), one Se(7), two equivalent Se(22), two equivalent Se(24), and two equivalent Se(6) atoms. In the sixth Ba site, Ba(6) is bonded in a 9-coordinate geometry to one Se(2), one Se(24), one Se(8), two equivalent Se(21), two equivalent Se(23), and two equivalent Se(5) atoms. There are thirteen inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one Se(13), two equivalent Se(16), and two equivalent Se(18) atoms to form distorted BiSe5 square pyramids that share corners with two equivalent Bi(12)Se6 octahedra, corners with two equivalent Bi(2)Se6 octahedra, corners with two equivalent Bi(3)Se6 octahedra, corners with two equivalent Bi(11)Se5 square pyramids,  an edgeedge with one Bi(3)Se6 octahedra,  an edgeedge with one Bi(11)Se5 square pyramid, and edges with two equivalent Bi(1)Se5 square pyramids. The corner-sharing octahedral tilt angles range from 5-83°. In the second Bi site, Bi(2) is bonded to one Se(14), one Se(16), two equivalent Se(15), and two equivalent Se(17) atoms to form BiSe6 octahedra that share corners with two equivalent Bi(12)Se6 octahedra, corners with two equivalent Bi(4)Se6 octahedra, corners with two equivalent Bi(1)Se5 square pyramids, corners with two equivalent Bi(11)Se5 square pyramids,  an edgeedge with one Bi(12)Se6 octahedra,  an edgeedge with one Bi(4)Se6 octahedra, edges with two equivalent Bi(13)Se6 octahedra, and edges with two equivalent Bi(2)Se6 octahedra. The corner-sharing octahedral tilt angles range from 4-10°. In the third Bi site, Bi(3) is bonded to one Se(1), one Se(21), two equivalent Se(18), and two equivalent Se(24) atoms to form BiSe6 octahedra that share corners with two equivalent Bi(1)Se5 square pyramids, edges with two equivalent Bi(12)Se6 octahedra, edges with two equivalent Bi(3)Se6 octahedra, and  an edgeedge with one Bi(1)Se5 square pyramid. In the fourth Bi site, Bi(4) is bonded to one Se(2), one Se(22), two equivalent Se(17), and two equivalent Se(23) atoms to form BiSe6 octahedra that share corners with two equivalent Bi(2)Se6 octahedra, corners with two equivalent Bi(11)Se5 square pyramids,  an edgeedge with one Bi(2)Se6 octahedra, and edges with two equivalent Bi(4)Se6 octahedra. The corner-sharing octahedral tilt angles are 10°. In the fifth Bi site, Bi(5) is bonded to one Se(11), one Se(25), two equivalent Se(12), and two equivalent Se(20) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles are 51°. In the sixth Bi site, Bi(6) is bonded to one Se(12), one Se(26), two equivalent Se(11), and two equivalent Se(19) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles are 57°. In the seventh Bi site, Bi(7) is bonded to one Se(19), one Se(7), two equivalent Se(26), and two equivalent Se(4) atoms to form BiSe6 octahedra that share corners with two equivalent Bi(10)Se5 square pyramids, corners with two equivalent Bi(9)Se5 square pyramids, edges with two equivalent Bi(6)Se6 octahedra, edges with two equivalent Bi(7)Se6 octahedra, and  an edgeedge with one Bi(9)Se5 square pyramid. In the eighth Bi site, Bi(8) is bonded to one Se(20), one Se(8), two equivalent Se(25), and two equivalent Se(3) atoms to form BiSe6 octahedra that share corners with two equivalent Bi(10)Se5 square pyramids, corners with two equivalent Bi(9)Se5 square pyramids, edges with two equivalent Bi(5)Se6 octahedra, edges with two equivalent Bi(8)Se6 octahedra, and  an edgeedge with one Bi(10)Se5 square pyramid. In the ninth Bi site, Bi(9) is bonded to one Se(5), two equivalent Se(4), and two equivalent Se(8) atoms to form distorted BiSe5 square pyramids that share corners with two equivalent Bi(7)Se6 octahedra, corners with two equivalent Bi(8)Se6 octahedra,  an edgeedge with one Bi(7)Se6 octahedra, and edges with two equivalent Bi(9)Se5 square pyramids. The corner-sharing octahedral tilt angles range from 3-87°. In the tenth Bi site, Bi(10) is bonded to one Se(6), two equivalent Se(3), and two equivalent Se(7) atoms to form distorted BiSe5 square pyramids that share corners with two equivalent Bi(7)Se6 octahedra, corners with two equivalent Bi(8)Se6 octahedra,  an edgeedge with one Bi(8)Se6 octahedra, and edges with two equivalent Bi(10)Se5 square pyramids. The corner-sharing octahedral tilt angles range from 2-87°. In the eleventh Bi site, Bi(11) is bonded to one Se(9), two equivalent Se(16), and two equivalent Se(2) atoms to form distorted BiSe5 square pyramids that share corners with two equivalent Bi(2)Se6 octahedra, corners with two equivalent Bi(4)Se6 octahedra, corners with two equivalent Bi(1)Se5 square pyramids,  an edgeedge with one Bi(1)Se5 square pyramid, and edges with two equivalent Bi(11)Se5 square pyramids. The corner-sharing octahedral tilt angles range from 82-85°. In the twelfth Bi site, Bi(12) is bonded to one Se(10), one Se(18), two equivalent Se(1), and two equivalent Se(15) atoms to form BiSe6 octahedra that share corners with two equivalent Bi(2)Se6 octahedra, corners with two equivalent Bi(1)Se5 square pyramids,  an edgeedge with one Bi(2)Se6 octahedra, edges with two equivalent Bi(12)Se6 octahedra, edges with two equivalent Bi(13)Se6 octahedra, and edges with two equivalent Bi(3)Se6 octahedra. The corner-sharing octahedral tilt angles are 4°. In the thirteenth Bi site, Bi(13) is bonded to one Se(11), one Se(15), two equivalent Se(10), and two equivalent Se(14) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles range from 51-57°. There are twenty-six inequivalent Se sites. In the first Se site, Se(1) is bonded to one Ba(3), one Ba(5), one Bi(3), and two equivalent Bi(12) atoms to form distorted SeBa2Bi3 trigonal bipyramids that share  a cornercorner with one Se(21)Ba4Bi square pyramid,  a cornercorner with one Se(3)BaBi4 square pyramid, corners with two equivalent Se(20)Ba2Bi3 square pyramids, corners with two equivalent Se(22)Ba4Bi square pyramids, corners with two equivalent Se(15)Bi5 square pyramids,  a cornercorner with one Se(7)Ba2Bi3 trigonal bipyramid,  a cornercorner with one Se(23)Ba3Bi2 trigonal bipyramid, corners with two equivalent Se(1)Ba2Bi3 trigonal bipyramids, edges with two equivalent Se(18)BaBi5 octahedra,  an edgeedge with one Se(15)Bi5 square pyramid, edges with two equivalent Se(10)Ba2Bi3 square pyramids, edges with two equivalent Se(6)Ba4Bi square pyramids, and edges with two equivalent Se(24)Ba3Bi2 trigonal bipyramids. In the second Se site, Se(2) is bonded to one Ba(4), one Ba(6), one Bi(4), and two equivalent Bi(11) atoms to form SeBa2Bi3 trigonal bipyramids that share  a cornercorner with one Se(22)Ba4Bi square pyramid,  a cornercorner with one Se(4)BaBi4 square pyramid, corners with two equivalent Se(19)Ba2Bi3 square pyramids, corners with two equivalent Se(21)Ba4Bi square pyramids, corners with two equivalent Se(17)BaBi4 square pyramids, corners with two equivalent Se(16)Bi5 square pyramids,  a cornercorner with one Se(8)Ba2Bi3 trigonal bipyramid,  a cornercorner with one Se(24)Ba3Bi2 trigonal bipyramid, corners with two equivalent Se(2)Ba2Bi3 trigonal bipyramids,  an edgeedge with one Se(16)Bi5 square pyramid, edges with two equivalent Se(5)Ba4Bi square pyramids, and edges with two equivalent Se(23)Ba3Bi2 trigonal bipyramids. In the third Se site, Se(3) is bonded to one Ba(3), two equivalent Bi(10), and two equivalent Bi(8) atoms to form SeBaBi4 square pyramids that share corners with two equivalent Se(10)Ba2Bi3 square pyramids,  a cornercorner with one Se(1)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(25)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(7)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(8)Ba2Bi3 trigonal bipyramids, edges with two equivalent Se(20)Ba2Bi3 square pyramids, edges with two equivalent Se(6)Ba4Bi square pyramids, edges with two equivalent Se(3)BaBi4 square pyramids,  an edgeedge with one Se(25)Ba2Bi3 trigonal bipyramid, and  an edgeedge with one Se(7)Ba2Bi3 trigonal bipyramid. In the fourth Se site, Se(4) is bonded to one Ba(4), two equivalent Bi(7), and two equivalent Bi(9) atoms to form distorted SeBaBi4 square pyramids that share  a cornercorner with one Se(2)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(26)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(7)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(8)Ba2Bi3 trigonal bipyramids, edges with two equivalent Se(19)Ba2Bi3 square pyramids, edges with two equivalent Se(5)Ba4Bi square pyramids, edges with two equivalent Se(4)BaBi4 square pyramids,  an edgeedge with one Se(26)Ba2Bi3 trigonal bipyramid, and  an edgeedge with one Se(8)Ba2Bi3 trigonal bipyramid. In the fifth Se site, Se(5) is bonded to two equivalent Ba(4), two equivalent Ba(6), and one Bi(9) atom to form distorted SeBa4Bi square pyramids that share corners with two equivalent Se(19)Ba2Bi3 square pyramids, corners with two equivalent Se(21)Ba4Bi square pyramids, corners with two equivalent Se(23)Ba3Bi2 trigonal bipyramids, corners with two equivalent Se(24)Ba3Bi2 trigonal bipyramids,  an edgeedge with one Se(19)Ba2Bi3 square pyramid,  an edgeedge with one Se(21)Ba4Bi square pyramid, edges with two equivalent Se(5)Ba4Bi square pyramids, edges with two equivalent Se(4)BaBi4 square pyramids,  an edgeedge with one Se(23)Ba3Bi2 trigonal bipyramid, edges with two equivalent Se(2)Ba2Bi3 trigonal bipyramids, and edges with two equivalent Se(8)Ba2Bi3 trigonal bipyramids. In the sixth Se site, Se(6) is bonded to two equivalent Ba(3), two equivalent Ba(5), and one Bi(10) atom to form SeBa4Bi square pyramids that share corners with two equivalent Se(10)Ba2Bi3 square pyramids, corners with two equivalent Se(20)Ba2Bi3 square pyramids, corners with two equivalent Se(22)Ba4Bi square pyramids, corners with two equivalent Se(23)Ba3Bi2 trigonal bipyramids, corners with two equivalent Se(24)Ba3Bi2 trigonal bipyramids,  an edgeedge with one Se(10)Ba2Bi3 square pyramid,  an edgeedge with one Se(20)Ba2Bi3 square pyramid,  an edgeedge with one Se(22)Ba4Bi square pyramid, edges with two equivalent Se(6)Ba4Bi square pyramids, edges with two equivalent Se(3)BaBi4 square pyramids,  an edgeedge with one Se(24)Ba3Bi2 trigonal bipyramid, edges with two equivalent Se(1)Ba2Bi3 trigonal bipyramids, and edges with two equivalent Se(7)Ba2Bi3 trigonal bipyramids. In the seventh Se site, Se(7) is bonded to one Ba(1), one Ba(5), one Bi(7), and two equivalent Bi(10) atoms to form SeBa2Bi3 trigonal bipyramids that share  a cornercorner with one Se(19)Ba2Bi3 square pyramid,  a cornercorner with one Se(17)BaBi4 square pyramid, corners with two equivalent Se(14)Ba2Bi3 square pyramids, corners with two equivalent Se(3)BaBi4 square pyramids, corners with two equivalent Se(4)BaBi4 square pyramids,  a cornercorner with one Se(1)Ba2Bi3 trigonal bipyramid,  a cornercorner with one Se(23)Ba3Bi2 trigonal bipyramid, corners with two equivalent Se(7)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(24)Ba3Bi2 trigonal bipyramids,  an edgeedge with one Se(3)BaBi4 square pyramid, edges with two equivalent Se(22)Ba4Bi square pyramids, edges with two equivalent Se(6)Ba4Bi square pyramids, and edges with two equivalent Se(26)Ba2Bi3 trigonal bipyramids. In the eighth Se site, Se(8) is bonded to one Ba(2), one Ba(6), one Bi(8), and two equivalent Bi(9) atoms to form SeBa2Bi3 trigonal bipyramids that share  a cornercorner with one Se(18)BaBi5 octahedra,  a cornercorner with one Se(20)Ba2Bi3 square pyramid, corners with two equivalent Se(3)BaBi4 square pyramids, corners with two equivalent Se(4)BaBi4 square pyramids,  a cornercorner with one Se(2)Ba2Bi3 trigonal bipyramid,  a cornercorner with one Se(24)Ba3Bi2 trigonal bipyramid, corners with two equivalent Se(8)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(23)Ba3Bi2 trigonal bipyramids,  an edgeedge with one Se(4)BaBi4 square pyramid, edges with two equivalent Se(21)Ba4Bi square pyramids, edges with two equivalent Se(5)Ba4Bi square pyramids, and edges with two equivalent Se(25)Ba2Bi3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 46°. In the ninth Se site, Se(9) is bonded in a 3-coordinate geometry to two equivalent Ba(4) and one Bi(11) atom. In the tenth Se site, Se(10) is bonded to two equivalent Ba(3), one Bi(12), and two equivalent Bi(13) atoms to form SeBa2Bi3 square pyramids that share  a cornercorner with one Se(18)BaBi5 octahedra, corners with two equivalent Se(14)Ba2Bi3 square pyramids, corners with two equivalent Se(20)Ba2Bi3 square pyramids, corners with two equivalent Se(6)Ba4Bi square pyramids, corners with two equivalent Se(3)BaBi4 square pyramids,  an edgeedge with one Se(14)Ba2Bi3 square pyramid,  an edgeedge with one Se(20)Ba2Bi3 square pyramid,  an edgeedge with one Se(6)Ba4Bi square pyramid, edges with two equivalent Se(10)Ba2Bi3 square pyramids, edges with two equivalent Se(15)Bi5 square pyramids, and edges with two equivalent Se(1)Ba2Bi3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 7°. In the eleventh Se site, Se(11) is bonded in a rectangular see-saw-like geometry to one Bi(13), one Bi(5), and two equivalent Bi(6) atoms. In the twelfth Se site, Se(12) is bonded in a distorted T-shaped geometry to one Bi(6) and two equivalent Bi(5) atoms. In the thirteenth Se site, Se(13) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Ba(2) and one Bi(1) atom. In the fourteenth Se site, Se(14) is bonded to two equivalent Ba(1), one Bi(2), and two equivalent Bi(13) atoms to form SeBa2Bi3 square pyramids that share  a cornercorner with one Se(16)Bi5 square pyramid, corners with two equivalent Se(10)Ba2Bi3 square pyramids, corners with two equivalent Se(22)Ba4Bi square pyramids, corners with two equivalent Se(26)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(7)Ba2Bi3 trigonal bipyramids,  an edgeedge with one Se(10)Ba2Bi3 square pyramid,  an edgeedge with one Se(22)Ba4Bi square pyramid, edges with two equivalent Se(14)Ba2Bi3 square pyramids, edges with two equivalent Se(17)BaBi4 square pyramids, edges with two equivalent Se(15)Bi5 square pyramids, and  an edgeedge with one Se(26)Ba2Bi3 trigonal bipyramid. In the fifteenth Se site, Se(15) is bonded to one Bi(13), two equivalent Bi(12), and two equivalent Bi(2) atoms to form distorted SeBi5 square pyramids that share corners with two equivalent Se(18)BaBi5 octahedra, corners with two equivalent Se(17)BaBi4 square pyramids, corners with two equivalent Se(16)Bi5 square pyramids, corners with two equivalent Se(1)Ba2Bi3 trigonal bipyramids,  an edgeedge with one Se(17)BaBi4 square pyramid, edges with two equivalent Se(10)Ba2Bi3 square pyramids, edges with two equivalent Se(14)Ba2Bi3 square pyramids, edges with two equivalent Se(15)Bi5 square pyramids, and  an edgeedge with one Se(1)Ba2Bi3 trigonal bipyramid. The corner-sharing octahedral tilt angles are 90°. In the sixteenth Se site, Se(16) is bonded to one Bi(2), two equivalent Bi(1), and two equivalent Bi(11) atoms to form SeBi5 square pyramids that share corners with two equivalent Se(18)BaBi5 octahedra,  a cornercorner with one Se(14)Ba2Bi3 square pyramid, corners with two equivalent Se(17)BaBi4 square pyramids, corners with two equivalent Se(15)Bi5 square pyramids, corners with two equivalent Se(2)Ba2Bi3 trigonal bipyramids,  an edgeedge with one Se(18)BaBi5 octahedra, edges with two equivalent Se(16)Bi5 square pyramids, and  an edgeedge with one Se(2)Ba2Bi3 trigonal bipyramid. The corner-sharing octahedral tilt angles are 14°. In the seventeenth Se site, Se(17) is bonded to one Ba(1), two equivalent Bi(2), and two equivalent Bi(4) atoms to form SeBaBi4 square pyramids that share corners with two equivalent Se(15)Bi5 square pyramids, corners with two equivalent Se(16)Bi5 square pyramids,  a cornercorner with one Se(7)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(2)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(26)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(23)Ba3Bi2 trigonal bipyramids,  an edgeedge with one Se(15)Bi5 square pyramid, edges with two equivalent Se(14)Ba2Bi3 square pyramids, edges with two equivalent Se(22)Ba4Bi square pyramids, edges with two equivalent Se(17)BaBi4 square pyramids, and  an edgeedge with one Se(23)Ba3Bi2 trigonal bipyramid. In the eighteenth Se site, Se(18) is bonded to one Ba(2), one Bi(12), two equivalent Bi(1), and two equivalent Bi(3) atoms to form SeBaBi5 octahedra that share  a cornercorner with one Se(10)Ba2Bi3 square pyramid, corners with two equivalent Se(15)Bi5 square pyramids, corners with two equivalent Se(16)Bi5 square pyramids,  a cornercorner with one Se(8)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(25)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(24)Ba3Bi2 trigonal bipyramids, edges with two equivalent Se(18)BaBi5 octahedra,  an edgeedge with one Se(16)Bi5 square pyramid, edges with two equivalent Se(21)Ba4Bi square pyramids,  an edgeedge with one Se(24)Ba3Bi2 trigonal bipyramid, and edges with two equivalent Se(1)Ba2Bi3 trigonal bipyramids. In the nineteenth Se site, Se(19) is bonded to two equivalent Ba(4), one Bi(7), and two equivalent Bi(6) atoms to form SeBa2Bi3 square pyramids that share corners with two equivalent Se(5)Ba4Bi square pyramids,  a cornercorner with one Se(7)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(2)Ba2Bi3 trigonal bipyramids,  an edgeedge with one Se(5)Ba4Bi square pyramid, edges with two equivalent Se(19)Ba2Bi3 square pyramids, edges with two equivalent Se(4)BaBi4 square pyramids, and edges with two equivalent Se(26)Ba2Bi3 trigonal bipyramids. In the twentieth Se site, Se(20) is bonded to two equivalent Ba(3), one Bi(8), and two equivalent Bi(5) atoms to form SeBa2Bi3 square pyramids that share corners with two equivalent Se(10)Ba2Bi3 square pyramids, corners with two equivalent Se(6)Ba4Bi square pyramids,  a cornercorner with one Se(8)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(1)Ba2Bi3 trigonal bipyramids,  an edgeedge with one Se(10)Ba2Bi3 square pyramid,  an edgeedge with one Se(6)Ba4Bi square pyramid, edges with two equivalent Se(20)Ba2Bi3 square pyramids, edges with two equivalent Se(3)BaBi4 square pyramids, and edges with two equivalent Se(25)Ba2Bi3 trigonal bipyramids. In the twenty-first Se site, Se(21) is bonded to two equivalent Ba(2), two equivalent Ba(6), and one Bi(3) atom to form SeBa4Bi square pyramids that share corners with two equivalent Se(5)Ba4Bi square pyramids,  a cornercorner with one Se(1)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(2)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(25)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(23)Ba3Bi2 trigonal bipyramids, edges with two equivalent Se(18)BaBi5 octahedra,  an edgeedge with one Se(5)Ba4Bi square pyramid, edges with two equivalent Se(21)Ba4Bi square pyramids,  an edgeedge with one Se(25)Ba2Bi3 trigonal bipyramid,  an edgeedge with one Se(23)Ba3Bi2 trigonal bipyramid, edges with two equivalent Se(8)Ba2Bi3 trigonal bipyramids, and edges with two equivalent Se(24)Ba3Bi2 trigonal bipyramids. In the twenty-second Se site, Se(22) is bonded to two equivalent Ba(1), two equivalent Ba(5), and one Bi(4) atom to form SeBa4Bi square pyramids that share corners with two equivalent Se(14)Ba2Bi3 square pyramids, corners with two equivalent Se(6)Ba4Bi square pyramids,  a cornercorner with one Se(2)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(1)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(26)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(24)Ba3Bi2 trigonal bipyramids,  an edgeedge with one Se(14)Ba2Bi3 square pyramid,  an edgeedge with one Se(6)Ba4Bi square pyramid, edges with two equivalent Se(22)Ba4Bi square pyramids, edges with two equivalent Se(17)BaBi4 square pyramids,  an edgeedge with one Se(26)Ba2Bi3 trigonal bipyramid,  an edgeedge with one Se(24)Ba3Bi2 trigonal bipyramid, edges with two equivalent Se(7)Ba2Bi3 trigonal bipyramids, and edges with two equivalent Se(23)Ba3Bi2 trigonal bipyramids. In the twenty-third Se site, Se(23) is bonded to one Ba(5), two equivalent Ba(6), and two equivalent Bi(4) atoms to form distorted SeBa3Bi2 trigonal bipyramids that share corners with two equivalent Se(21)Ba4Bi square pyramids, corners with two equivalent Se(5)Ba4Bi square pyramids, corners with two equivalent Se(6)Ba4Bi square pyramids, corners with two equivalent Se(17)BaBi4 square pyramids,  a cornercorner with one Se(1)Ba2Bi3 trigonal bipyramid,  a cornercorner with one Se(7)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(8)Ba2Bi3 trigonal bipyramids,  an edgeedge with one Se(21)Ba4Bi square pyramid,  an edgeedge with one Se(5)Ba4Bi square pyramid,  an edgeedge with one Se(17)BaBi4 square pyramid, edges with two equivalent Se(22)Ba4Bi square pyramids, edges with two equivalent Se(2)Ba2Bi3 trigonal bipyramids, edges with two equivalent Se(23)Ba3Bi2 trigonal bipyramids, and edges with two equivalent Se(24)Ba3Bi2 trigonal bipyramids. In the twenty-fourth Se site, Se(24) is bonded to one Ba(6), two equivalent Ba(5), and two equivalent Bi(3) atoms to form distorted SeBa3Bi2 trigonal bipyramids that share corners with two equivalent Se(18)BaBi5 octahedra, corners with two equivalent Se(22)Ba4Bi square pyramids, corners with two equivalent Se(5)Ba4Bi square pyramids, corners with two equivalent Se(6)Ba4Bi square pyramids,  a cornercorner with one Se(2)Ba2Bi3 trigonal bipyramid,  a cornercorner with one Se(8)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(7)Ba2Bi3 trigonal bipyramids,  an edgeedge with one Se(18)BaBi5 octahedra,  an edgeedge with one Se(22)Ba4Bi square pyramid,  an edgeedge with one Se(6)Ba4Bi square pyramid, edges with two equivalent Se(21)Ba4Bi square pyramids, edges with two equivalent Se(1)Ba2Bi3 trigonal bipyramids, edges with two equivalent Se(23)Ba3Bi2 trigonal bipyramids, and edges with two equivalent Se(24)Ba3Bi2 trigonal bipyramids. The corner-sharing octahedral tilt angles are 10°. In the twenty-fifth Se site, Se(25) is bonded to two equivalent Ba(2), one Bi(5), and two equivalent Bi(8) atoms to form SeBa2Bi3 trigonal bipyramids that share corners with two equivalent Se(18)BaBi5 octahedra, corners with two equivalent Se(21)Ba4Bi square pyramids, corners with two equivalent Se(3)BaBi4 square pyramids,  an edgeedge with one Se(21)Ba4Bi square pyramid,  an edgeedge with one Se(3)BaBi4 square pyramid, edges with two equivalent Se(20)Ba2Bi3 square pyramids, edges with two equivalent Se(25)Ba2Bi3 trigonal bipyramids, and edges with two equivalent Se(8)Ba2Bi3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 42°. In the twenty-sixth Se site, Se(26) is bonded to two equivalent Ba(1), one Bi(6), and two equivalent Bi(7) atoms to form SeBa2Bi3 trigonal bipyramids that share corners with two equivalent Se(14)Ba2Bi3 square pyramids, corners with two equivalent Se(22)Ba4Bi square pyramids, corners with two equivalent Se(17)BaBi4 square pyramids, corners with two equivalent Se(4)BaBi4 square pyramids,  an edgeedge with one Se(14)Ba2Bi3 square pyramid,  an edgeedge with one Se(22)Ba4Bi square pyramid,  an edgeedge with one Se(4)BaBi4 square pyramid, edges with two equivalent Se(19)Ba2Bi3 square pyramids, edges with two equivalent Se(26)Ba2Bi3 trigonal bipyramids, and edges with two equivalent Se(7)Ba2Bi3 trigonal bipyramids.
Ba6(BiSe2)13 crystallizes in the monoclinic Pm space group. There are six inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to one Se(17), one Se(7), two equivalent Se(14), two equivalent Se(22), and two equivalent Se(26) atoms. The Ba(1)-Se(17) bond length is 3.46 Å. The Ba(1)-Se(7) bond length is 3.45 Å. Both Ba(1)-Se(14) bond lengths are 3.42 Å. Both Ba(1)-Se(22) bond lengths are 3.28 Å. Both Ba(1)-Se(26) bond lengths are 3.42 Å. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one Se(18), one Se(8), two equivalent Se(13), two equivalent Se(21), and two equivalent Se(25) atoms. The Ba(2)-Se(18) bond length is 3.54 Å. The Ba(2)-Se(8) bond length is 3.58 Å. Both Ba(2)-Se(13) bond lengths are 3.27 Å. Both Ba(2)-Se(21) bond lengths are 3.36 Å. Both Ba(2)-Se(25) bond lengths are 3.48 Å. In the third Ba site, Ba(3) is bonded in a 8-coordinate geometry to one Se(1), one Se(3), two equivalent Se(10), two equivalent Se(20), and two equivalent Se(6) atoms. The Ba(3)-Se(1) bond length is 3.52 Å. The Ba(3)-Se(3) bond length is 3.45 Å. Both Ba(3)-Se(10) bond lengths are 3.43 Å. Both Ba(3)-Se(20) bond lengths are 3.35 Å. Both Ba(3)-Se(6) bond lengths are 3.32 Å. In the fourth Ba site, Ba(4) is bonded in a 8-coordinate geometry to one Se(2), one Se(4), two equivalent Se(19), two equivalent Se(5), and two equivalent Se(9) atoms. The Ba(4)-Se(2) bond length is 3.52 Å. The Ba(4)-Se(4) bond length is 3.59 Å. Both Ba(4)-Se(19) bond lengths are 3.44 Å. Both Ba(4)-Se(5) bond lengths are 3.35 Å. Both Ba(4)-Se(9) bond lengths are 3.28 Å. In the fifth Ba site, Ba(5) is bonded in a 9-coordinate geometry to one Se(1), one Se(23), one Se(7), two equivalent Se(22), two equivalent Se(24), and two equivalent Se(6) atoms. The Ba(5)-Se(1) bond length is 3.65 Å. The Ba(5)-Se(23) bond length is 3.55 Å. The Ba(5)-Se(7) bond length is 3.61 Å. Both Ba(5)-Se(22) bond lengths are 3.33 Å. Both Ba(5)-Se(24) bond lengths are 3.56 Å. Both Ba(5)-Se(6) bond lengths are 3.39 Å. In the sixth Ba site, Ba(6) is bonded in a 9-coordinate geometry to one Se(2), one Se(24), one Se(8), two equivalent Se(21), two equivalent Se(23), and two equivalent Se(5) atoms. The Ba(6)-Se(2) bond length is 3.60 Å. The Ba(6)-Se(24) bond length is 3.60 Å. The Ba(6)-Se(8) bond length is 3.59 Å. Both Ba(6)-Se(21) bond lengths are 3.32 Å. Both Ba(6)-Se(23) bond lengths are 3.60 Å. Both Ba(6)-Se(5) bond lengths are 3.37 Å. There are thirteen inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one Se(13), two equivalent Se(16), and two equivalent Se(18) atoms to form distorted BiSe5 square pyramids that share corners with two equivalent Bi(12)Se6 octahedra, corners with two equivalent Bi(2)Se6 octahedra, corners with two equivalent Bi(3)Se6 octahedra, corners with two equivalent Bi(11)Se5 square pyramids,  an edgeedge with one Bi(3)Se6 octahedra,  an edgeedge with one Bi(11)Se5 square pyramid, and edges with two equivalent Bi(1)Se5 square pyramids. The corner-sharing octahedral tilt angles range from 5-83°. The Bi(1)-Se(13) bond length is 2.61 Å. Both Bi(1)-Se(16) bond lengths are 3.02 Å. Both Bi(1)-Se(18) bond lengths are 3.06 Å. In the second Bi site, Bi(2) is bonded to one Se(14), one Se(16), two equivalent Se(15), and two equivalent Se(17) atoms to form BiSe6 octahedra that share corners with two equivalent Bi(12)Se6 octahedra, corners with two equivalent Bi(4)Se6 octahedra, corners with two equivalent Bi(1)Se5 square pyramids, corners with two equivalent Bi(11)Se5 square pyramids,  an edgeedge with one Bi(12)Se6 octahedra,  an edgeedge with one Bi(4)Se6 octahedra, edges with two equivalent Bi(13)Se6 octahedra, and edges with two equivalent Bi(2)Se6 octahedra. The corner-sharing octahedral tilt angles range from 4-10°. The Bi(2)-Se(14) bond length is 2.98 Å. The Bi(2)-Se(16) bond length is 2.93 Å. Both Bi(2)-Se(15) bond lengths are 3.04 Å. Both Bi(2)-Se(17) bond lengths are 2.95 Å. In the third Bi site, Bi(3) is bonded to one Se(1), one Se(21), two equivalent Se(18), and two equivalent Se(24) atoms to form BiSe6 octahedra that share corners with two equivalent Bi(1)Se5 square pyramids, edges with two equivalent Bi(12)Se6 octahedra, edges with two equivalent Bi(3)Se6 octahedra, and  an edgeedge with one Bi(1)Se5 square pyramid. The Bi(3)-Se(1) bond length is 3.25 Å. The Bi(3)-Se(21) bond length is 2.76 Å. Both Bi(3)-Se(18) bond lengths are 3.16 Å. Both Bi(3)-Se(24) bond lengths are 2.88 Å. In the fourth Bi site, Bi(4) is bonded to one Se(2), one Se(22), two equivalent Se(17), and two equivalent Se(23) atoms to form BiSe6 octahedra that share corners with two equivalent Bi(2)Se6 octahedra, corners with two equivalent Bi(11)Se5 square pyramids,  an edgeedge with one Bi(2)Se6 octahedra, and edges with two equivalent Bi(4)Se6 octahedra. The corner-sharing octahedral tilt angles are 10°. The Bi(4)-Se(2) bond length is 3.08 Å. The Bi(4)-Se(22) bond length is 2.81 Å. Both Bi(4)-Se(17) bond lengths are 3.22 Å. Both Bi(4)-Se(23) bond lengths are 2.86 Å. In the fifth Bi site, Bi(5) is bonded to one Se(11), one Se(25), two equivalent Se(12), and two equivalent Se(20) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles are 51°. The Bi(5)-Se(11) bond length is 3.01 Å. The Bi(5)-Se(25) bond length is 2.97 Å. Both Bi(5)-Se(12) bond lengths are 2.90 Å. Both Bi(5)-Se(20) bond lengths are 3.11 Å. In the sixth Bi site, Bi(6) is bonded to one Se(12), one Se(26), two equivalent Se(11), and two equivalent Se(19) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles are 57°. The Bi(6)-Se(12) bond length is 2.90 Å. The Bi(6)-Se(26) bond length is 3.09 Å. Both Bi(6)-Se(11) bond lengths are 2.93 Å. Both Bi(6)-Se(19) bond lengths are 3.03 Å. In the seventh Bi site, Bi(7) is bonded to one Se(19), one Se(7), two equivalent Se(26), and two equivalent Se(4) atoms to form BiSe6 octahedra that share corners with two equivalent Bi(10)Se5 square pyramids, corners with two equivalent Bi(9)Se5 square pyramids, edges with two equivalent Bi(6)Se6 octahedra, edges with two equivalent Bi(7)Se6 octahedra, and  an edgeedge with one Bi(9)Se5 square pyramid. The Bi(7)-Se(19) bond length is 2.84 Å. The Bi(7)-Se(7) bond length is 3.11 Å. Both Bi(7)-Se(26) bond lengths are 2.95 Å. Both Bi(7)-Se(4) bond lengths are 3.01 Å. In the eighth Bi site, Bi(8) is bonded to one Se(20), one Se(8), two equivalent Se(25), and two equivalent Se(3) atoms to form BiSe6 octahedra that share corners with two equivalent Bi(10)Se5 square pyramids, corners with two equivalent Bi(9)Se5 square pyramids, edges with two equivalent Bi(5)Se6 octahedra, edges with two equivalent Bi(8)Se6 octahedra, and  an edgeedge with one Bi(10)Se5 square pyramid. The Bi(8)-Se(20) bond length is 2.81 Å. The Bi(8)-Se(8) bond length is 3.13 Å. Both Bi(8)-Se(25) bond lengths are 2.96 Å. Both Bi(8)-Se(3) bond lengths are 3.01 Å. In the ninth Bi site, Bi(9) is bonded to one Se(5), two equivalent Se(4), and two equivalent Se(8) atoms to form distorted BiSe5 square pyramids that share corners with two equivalent Bi(7)Se6 octahedra, corners with two equivalent Bi(8)Se6 octahedra,  an edgeedge with one Bi(7)Se6 octahedra, and edges with two equivalent Bi(9)Se5 square pyramids. The corner-sharing octahedral tilt angles range from 3-87°. The Bi(9)-Se(5) bond length is 2.75 Å. Both Bi(9)-Se(4) bond lengths are 3.15 Å. Both Bi(9)-Se(8) bond lengths are 2.87 Å. In the tenth Bi site, Bi(10) is bonded to one Se(6), two equivalent Se(3), and two equivalent Se(7) atoms to form distorted BiSe5 square pyramids that share corners with two equivalent Bi(7)Se6 octahedra, corners with two equivalent Bi(8)Se6 octahedra,  an edgeedge with one Bi(8)Se6 octahedra, and edges with two equivalent Bi(10)Se5 square pyramids. The corner-sharing octahedral tilt angles range from 2-87°. The Bi(10)-Se(6) bond length is 2.76 Å. Both Bi(10)-Se(3) bond lengths are 3.13 Å. Both Bi(10)-Se(7) bond lengths are 2.86 Å. In the eleventh Bi site, Bi(11) is bonded to one Se(9), two equivalent Se(16), and two equivalent Se(2) atoms to form distorted BiSe5 square pyramids that share corners with two equivalent Bi(2)Se6 octahedra, corners with two equivalent Bi(4)Se6 octahedra, corners with two equivalent Bi(1)Se5 square pyramids,  an edgeedge with one Bi(1)Se5 square pyramid, and edges with two equivalent Bi(11)Se5 square pyramids. The corner-sharing octahedral tilt angles range from 82-85°. The Bi(11)-Se(9) bond length is 2.65 Å. Both Bi(11)-Se(16) bond lengths are 3.21 Å. Both Bi(11)-Se(2) bond lengths are 2.87 Å. In the twelfth Bi site, Bi(12) is bonded to one Se(10), one Se(18), two equivalent Se(1), and two equivalent Se(15) atoms to form BiSe6 octahedra that share corners with two equivalent Bi(2)Se6 octahedra, corners with two equivalent Bi(1)Se5 square pyramids,  an edgeedge with one Bi(2)Se6 octahedra, edges with two equivalent Bi(12)Se6 octahedra, edges with two equivalent Bi(13)Se6 octahedra, and edges with two equivalent Bi(3)Se6 octahedra. The corner-sharing octahedral tilt angles are 4°. The Bi(12)-Se(10) bond length is 2.86 Å. The Bi(12)-Se(18) bond length is 3.11 Å. Both Bi(12)-Se(1) bond lengths are 2.85 Å. Both Bi(12)-Se(15) bond lengths are 3.18 Å. In the thirteenth Bi site, Bi(13) is bonded to one Se(11), one Se(15), two equivalent Se(10), and two equivalent Se(14) atoms to form a mixture of edge and corner-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles range from 51-57°. The Bi(13)-Se(11) bond length is 3.00 Å. The Bi(13)-Se(15) bond length is 2.95 Å. Both Bi(13)-Se(10) bond lengths are 3.00 Å. Both Bi(13)-Se(14) bond lengths are 2.95 Å. There are twenty-six inequivalent Se sites. In the first Se site, Se(1) is bonded to one Ba(3), one Ba(5), one Bi(3), and two equivalent Bi(12) atoms to form distorted SeBa2Bi3 trigonal bipyramids that share  a cornercorner with one Se(21)Ba4Bi square pyramid,  a cornercorner with one Se(3)BaBi4 square pyramid, corners with two equivalent Se(20)Ba2Bi3 square pyramids, corners with two equivalent Se(22)Ba4Bi square pyramids, corners with two equivalent Se(15)Bi5 square pyramids,  a cornercorner with one Se(7)Ba2Bi3 trigonal bipyramid,  a cornercorner with one Se(23)Ba3Bi2 trigonal bipyramid, corners with two equivalent Se(1)Ba2Bi3 trigonal bipyramids, edges with two equivalent Se(18)BaBi5 octahedra,  an edgeedge with one Se(15)Bi5 square pyramid, edges with two equivalent Se(10)Ba2Bi3 square pyramids, edges with two equivalent Se(6)Ba4Bi square pyramids, and edges with two equivalent Se(24)Ba3Bi2 trigonal bipyramids. In the second Se site, Se(2) is bonded to one Ba(4), one Ba(6), one Bi(4), and two equivalent Bi(11) atoms to form SeBa2Bi3 trigonal bipyramids that share  a cornercorner with one Se(22)Ba4Bi square pyramid,  a cornercorner with one Se(4)BaBi4 square pyramid, corners with two equivalent Se(19)Ba2Bi3 square pyramids, corners with two equivalent Se(21)Ba4Bi square pyramids, corners with two equivalent Se(17)BaBi4 square pyramids, corners with two equivalent Se(16)Bi5 square pyramids,  a cornercorner with one Se(8)Ba2Bi3 trigonal bipyramid,  a cornercorner with one Se(24)Ba3Bi2 trigonal bipyramid, corners with two equivalent Se(2)Ba2Bi3 trigonal bipyramids,  an edgeedge with one Se(16)Bi5 square pyramid, edges with two equivalent Se(5)Ba4Bi square pyramids, and edges with two equivalent Se(23)Ba3Bi2 trigonal bipyramids. In the third Se site, Se(3) is bonded to one Ba(3), two equivalent Bi(10), and two equivalent Bi(8) atoms to form SeBaBi4 square pyramids that share corners with two equivalent Se(10)Ba2Bi3 square pyramids,  a cornercorner with one Se(1)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(25)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(7)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(8)Ba2Bi3 trigonal bipyramids, edges with two equivalent Se(20)Ba2Bi3 square pyramids, edges with two equivalent Se(6)Ba4Bi square pyramids, edges with two equivalent Se(3)BaBi4 square pyramids,  an edgeedge with one Se(25)Ba2Bi3 trigonal bipyramid, and  an edgeedge with one Se(7)Ba2Bi3 trigonal bipyramid. In the fourth Se site, Se(4) is bonded to one Ba(4), two equivalent Bi(7), and two equivalent Bi(9) atoms to form distorted SeBaBi4 square pyramids that share  a cornercorner with one Se(2)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(26)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(7)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(8)Ba2Bi3 trigonal bipyramids, edges with two equivalent Se(19)Ba2Bi3 square pyramids, edges with two equivalent Se(5)Ba4Bi square pyramids, edges with two equivalent Se(4)BaBi4 square pyramids,  an edgeedge with one Se(26)Ba2Bi3 trigonal bipyramid, and  an edgeedge with one Se(8)Ba2Bi3 trigonal bipyramid. In the fifth Se site, Se(5) is bonded to two equivalent Ba(4), two equivalent Ba(6), and one Bi(9) atom to form distorted SeBa4Bi square pyramids that share corners with two equivalent Se(19)Ba2Bi3 square pyramids, corners with two equivalent Se(21)Ba4Bi square pyramids, corners with two equivalent Se(23)Ba3Bi2 trigonal bipyramids, corners with two equivalent Se(24)Ba3Bi2 trigonal bipyramids,  an edgeedge with one Se(19)Ba2Bi3 square pyramid,  an edgeedge with one Se(21)Ba4Bi square pyramid, edges with two equivalent Se(5)Ba4Bi square pyramids, edges with two equivalent Se(4)BaBi4 square pyramids,  an edgeedge with one Se(23)Ba3Bi2 trigonal bipyramid, edges with two equivalent Se(2)Ba2Bi3 trigonal bipyramids, and edges with two equivalent Se(8)Ba2Bi3 trigonal bipyramids. In the sixth Se site, Se(6) is bonded to two equivalent Ba(3), two equivalent Ba(5), and one Bi(10) atom to form SeBa4Bi square pyramids that share corners with two equivalent Se(10)Ba2Bi3 square pyramids, corners with two equivalent Se(20)Ba2Bi3 square pyramids, corners with two equivalent Se(22)Ba4Bi square pyramids, corners with two equivalent Se(23)Ba3Bi2 trigonal bipyramids, corners with two equivalent Se(24)Ba3Bi2 trigonal bipyramids,  an edgeedge with one Se(10)Ba2Bi3 square pyramid,  an edgeedge with one Se(20)Ba2Bi3 square pyramid,  an edgeedge with one Se(22)Ba4Bi square pyramid, edges with two equivalent Se(6)Ba4Bi square pyramids, edges with two equivalent Se(3)BaBi4 square pyramids,  an edgeedge with one Se(24)Ba3Bi2 trigonal bipyramid, edges with two equivalent Se(1)Ba2Bi3 trigonal bipyramids, and edges with two equivalent Se(7)Ba2Bi3 trigonal bipyramids. In the seventh Se site, Se(7) is bonded to one Ba(1), one Ba(5), one Bi(7), and two equivalent Bi(10) atoms to form SeBa2Bi3 trigonal bipyramids that share  a cornercorner with one Se(19)Ba2Bi3 square pyramid,  a cornercorner with one Se(17)BaBi4 square pyramid, corners with two equivalent Se(14)Ba2Bi3 square pyramids, corners with two equivalent Se(3)BaBi4 square pyramids, corners with two equivalent Se(4)BaBi4 square pyramids,  a cornercorner with one Se(1)Ba2Bi3 trigonal bipyramid,  a cornercorner with one Se(23)Ba3Bi2 trigonal bipyramid, corners with two equivalent Se(7)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(24)Ba3Bi2 trigonal bipyramids,  an edgeedge with one Se(3)BaBi4 square pyramid, edges with two equivalent Se(22)Ba4Bi square pyramids, edges with two equivalent Se(6)Ba4Bi square pyramids, and edges with two equivalent Se(26)Ba2Bi3 trigonal bipyramids. In the eighth Se site, Se(8) is bonded to one Ba(2), one Ba(6), one Bi(8), and two equivalent Bi(9) atoms to form SeBa2Bi3 trigonal bipyramids that share  a cornercorner with one Se(18)BaBi5 octahedra,  a cornercorner with one Se(20)Ba2Bi3 square pyramid, corners with two equivalent Se(3)BaBi4 square pyramids, corners with two equivalent Se(4)BaBi4 square pyramids,  a cornercorner with one Se(2)Ba2Bi3 trigonal bipyramid,  a cornercorner with one Se(24)Ba3Bi2 trigonal bipyramid, corners with two equivalent Se(8)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(23)Ba3Bi2 trigonal bipyramids,  an edgeedge with one Se(4)BaBi4 square pyramid, edges with two equivalent Se(21)Ba4Bi square pyramids, edges with two equivalent Se(5)Ba4Bi square pyramids, and edges with two equivalent Se(25)Ba2Bi3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 46°. In the ninth Se site, Se(9) is bonded in a 3-coordinate geometry to two equivalent Ba(4) and one Bi(11) atom. In the tenth Se site, Se(10) is bonded to two equivalent Ba(3), one Bi(12), and two equivalent Bi(13) atoms to form SeBa2Bi3 square pyramids that share  a cornercorner with one Se(18)BaBi5 octahedra, corners with two equivalent Se(14)Ba2Bi3 square pyramids, corners with two equivalent Se(20)Ba2Bi3 square pyramids, corners with two equivalent Se(6)Ba4Bi square pyramids, corners with two equivalent Se(3)BaBi4 square pyramids,  an edgeedge with one Se(14)Ba2Bi3 square pyramid,  an edgeedge with one Se(20)Ba2Bi3 square pyramid,  an edgeedge with one Se(6)Ba4Bi square pyramid, edges with two equivalent Se(10)Ba2Bi3 square pyramids, edges with two equivalent Se(15)Bi5 square pyramids, and edges with two equivalent Se(1)Ba2Bi3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 7°. In the eleventh Se site, Se(11) is bonded in a rectangular see-saw-like geometry to one Bi(13), one Bi(5), and two equivalent Bi(6) atoms. In the twelfth Se site, Se(12) is bonded in a distorted T-shaped geometry to one Bi(6) and two equivalent Bi(5) atoms. In the thirteenth Se site, Se(13) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Ba(2) and one Bi(1) atom. In the fourteenth Se site, Se(14) is bonded to two equivalent Ba(1), one Bi(2), and two equivalent Bi(13) atoms to form SeBa2Bi3 square pyramids that share  a cornercorner with one Se(16)Bi5 square pyramid, corners with two equivalent Se(10)Ba2Bi3 square pyramids, corners with two equivalent Se(22)Ba4Bi square pyramids, corners with two equivalent Se(26)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(7)Ba2Bi3 trigonal bipyramids,  an edgeedge with one Se(10)Ba2Bi3 square pyramid,  an edgeedge with one Se(22)Ba4Bi square pyramid, edges with two equivalent Se(14)Ba2Bi3 square pyramids, edges with two equivalent Se(17)BaBi4 square pyramids, edges with two equivalent Se(15)Bi5 square pyramids, and  an edgeedge with one Se(26)Ba2Bi3 trigonal bipyramid. In the fifteenth Se site, Se(15) is bonded to one Bi(13), two equivalent Bi(12), and two equivalent Bi(2) atoms to form distorted SeBi5 square pyramids that share corners with two equivalent Se(18)BaBi5 octahedra, corners with two equivalent Se(17)BaBi4 square pyramids, corners with two equivalent Se(16)Bi5 square pyramids, corners with two equivalent Se(1)Ba2Bi3 trigonal bipyramids,  an edgeedge with one Se(17)BaBi4 square pyramid, edges with two equivalent Se(10)Ba2Bi3 square pyramids, edges with two equivalent Se(14)Ba2Bi3 square pyramids, edges with two equivalent Se(15)Bi5 square pyramids, and  an edgeedge with one Se(1)Ba2Bi3 trigonal bipyramid. The corner-sharing octahedral tilt angles are 90°. In the sixteenth Se site, Se(16) is bonded to one Bi(2), two equivalent Bi(1), and two equivalent Bi(11) atoms to form SeBi5 square pyramids that share corners with two equivalent Se(18)BaBi5 octahedra,  a cornercorner with one Se(14)Ba2Bi3 square pyramid, corners with two equivalent Se(17)BaBi4 square pyramids, corners with two equivalent Se(15)Bi5 square pyramids, corners with two equivalent Se(2)Ba2Bi3 trigonal bipyramids,  an edgeedge with one Se(18)BaBi5 octahedra, edges with two equivalent Se(16)Bi5 square pyramids, and  an edgeedge with one Se(2)Ba2Bi3 trigonal bipyramid. The corner-sharing octahedral tilt angles are 14°. In the seventeenth Se site, Se(17) is bonded to one Ba(1), two equivalent Bi(2), and two equivalent Bi(4) atoms to form SeBaBi4 square pyramids that share corners with two equivalent Se(15)Bi5 square pyramids, corners with two equivalent Se(16)Bi5 square pyramids,  a cornercorner with one Se(7)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(2)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(26)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(23)Ba3Bi2 trigonal bipyramids,  an edgeedge with one Se(15)Bi5 square pyramid, edges with two equivalent Se(14)Ba2Bi3 square pyramids, edges with two equivalent Se(22)Ba4Bi square pyramids, edges with two equivalent Se(17)BaBi4 square pyramids, and  an edgeedge with one Se(23)Ba3Bi2 trigonal bipyramid. In the eighteenth Se site, Se(18) is bonded to one Ba(2), one Bi(12), two equivalent Bi(1), and two equivalent Bi(3) atoms to form SeBaBi5 octahedra that share  a cornercorner with one Se(10)Ba2Bi3 square pyramid, corners with two equivalent Se(15)Bi5 square pyramids, corners with two equivalent Se(16)Bi5 square pyramids,  a cornercorner with one Se(8)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(25)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(24)Ba3Bi2 trigonal bipyramids, edges with two equivalent Se(18)BaBi5 octahedra,  an edgeedge with one Se(16)Bi5 square pyramid, edges with two equivalent Se(21)Ba4Bi square pyramids,  an edgeedge with one Se(24)Ba3Bi2 trigonal bipyramid, and edges with two equivalent Se(1)Ba2Bi3 trigonal bipyramids. In the nineteenth Se site, Se(19) is bonded to two equivalent Ba(4), one Bi(7), and two equivalent Bi(6) atoms to form SeBa2Bi3 square pyramids that share corners with two equivalent Se(5)Ba4Bi square pyramids,  a cornercorner with one Se(7)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(2)Ba2Bi3 trigonal bipyramids,  an edgeedge with one Se(5)Ba4Bi square pyramid, edges with two equivalent Se(19)Ba2Bi3 square pyramids, edges with two equivalent Se(4)BaBi4 square pyramids, and edges with two equivalent Se(26)Ba2Bi3 trigonal bipyramids. In the twentieth Se site, Se(20) is bonded to two equivalent Ba(3), one Bi(8), and two equivalent Bi(5) atoms to form SeBa2Bi3 square pyramids that share corners with two equivalent Se(10)Ba2Bi3 square pyramids, corners with two equivalent Se(6)Ba4Bi square pyramids,  a cornercorner with one Se(8)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(1)Ba2Bi3 trigonal bipyramids,  an edgeedge with one Se(10)Ba2Bi3 square pyramid,  an edgeedge with one Se(6)Ba4Bi square pyramid, edges with two equivalent Se(20)Ba2Bi3 square pyramids, edges with two equivalent Se(3)BaBi4 square pyramids, and edges with two equivalent Se(25)Ba2Bi3 trigonal bipyramids. In the twenty-first Se site, Se(21) is bonded to two equivalent Ba(2), two equivalent Ba(6), and one Bi(3) atom to form SeBa4Bi square pyramids that share corners with two equivalent Se(5)Ba4Bi square pyramids,  a cornercorner with one Se(1)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(2)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(25)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(23)Ba3Bi2 trigonal bipyramids, edges with two equivalent Se(18)BaBi5 octahedra,  an edgeedge with one Se(5)Ba4Bi square pyramid, edges with two equivalent Se(21)Ba4Bi square pyramids,  an edgeedge with one Se(25)Ba2Bi3 trigonal bipyramid,  an edgeedge with one Se(23)Ba3Bi2 trigonal bipyramid, edges with two equivalent Se(8)Ba2Bi3 trigonal bipyramids, and edges with two equivalent Se(24)Ba3Bi2 trigonal bipyramids. In the twenty-second Se site, Se(22) is bonded to two equivalent Ba(1), two equivalent Ba(5), and one Bi(4) atom to form SeBa4Bi square pyramids that share corners with two equivalent Se(14)Ba2Bi3 square pyramids, corners with two equivalent Se(6)Ba4Bi square pyramids,  a cornercorner with one Se(2)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(1)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(26)Ba2Bi3 trigonal bipyramids, corners with two equivalent Se(24)Ba3Bi2 trigonal bipyramids,  an edgeedge with one Se(14)Ba2Bi3 square pyramid,  an edgeedge with one Se(6)Ba4Bi square pyramid, edges with two equivalent Se(22)Ba4Bi square pyramids, edges with two equivalent Se(17)BaBi4 square pyramids,  an edgeedge with one Se(26)Ba2Bi3 trigonal bipyramid,  an edgeedge with one Se(24)Ba3Bi2 trigonal bipyramid, edges with two equivalent Se(7)Ba2Bi3 trigonal bipyramids, and edges with two equivalent Se(23)Ba3Bi2 trigonal bipyramids. In the twenty-third Se site, Se(23) is bonded to one Ba(5), two equivalent Ba(6), and two equivalent Bi(4) atoms to form distorted SeBa3Bi2 trigonal bipyramids that share corners with two equivalent Se(21)Ba4Bi square pyramids, corners with two equivalent Se(5)Ba4Bi square pyramids, corners with two equivalent Se(6)Ba4Bi square pyramids, corners with two equivalent Se(17)BaBi4 square pyramids,  a cornercorner with one Se(1)Ba2Bi3 trigonal bipyramid,  a cornercorner with one Se(7)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(8)Ba2Bi3 trigonal bipyramids,  an edgeedge with one Se(21)Ba4Bi square pyramid,  an edgeedge with one Se(5)Ba4Bi square pyramid,  an edgeedge with one Se(17)BaBi4 square pyramid, edges with two equivalent Se(22)Ba4Bi square pyramids, edges with two equivalent Se(2)Ba2Bi3 trigonal bipyramids, edges with two equivalent Se(23)Ba3Bi2 trigonal bipyramids, and edges with two equivalent Se(24)Ba3Bi2 trigonal bipyramids. In the twenty-fourth Se site, Se(24) is bonded to one Ba(6), two equivalent Ba(5), and two equivalent Bi(3) atoms to form distorted SeBa3Bi2 trigonal bipyramids that share corners with two equivalent Se(18)BaBi5 octahedra, corners with two equivalent Se(22)Ba4Bi square pyramids, corners with two equivalent Se(5)Ba4Bi square pyramids, corners with two equivalent Se(6)Ba4Bi square pyramids,  a cornercorner with one Se(2)Ba2Bi3 trigonal bipyramid,  a cornercorner with one Se(8)Ba2Bi3 trigonal bipyramid, corners with two equivalent Se(7)Ba2Bi3 trigonal bipyramids,  an edgeedge with one Se(18)BaBi5 octahedra,  an edgeedge with one Se(22)Ba4Bi square pyramid,  an edgeedge with one Se(6)Ba4Bi square pyramid, edges with two equivalent Se(21)Ba4Bi square pyramids, edges with two equivalent Se(1)Ba2Bi3 trigonal bipyramids, edges with two equivalent Se(23)Ba3Bi2 trigonal bipyramids, and edges with two equivalent Se(24)Ba3Bi2 trigonal bipyramids. The corner-sharing octahedral tilt angles are 10°. In the twenty-fifth Se site, Se(25) is bonded to two equivalent Ba(2), one Bi(5), and two equivalent Bi(8) atoms to form SeBa2Bi3 trigonal bipyramids that share corners with two equivalent Se(18)BaBi5 octahedra, corners with two equivalent Se(21)Ba4Bi square pyramids, corners with two equivalent Se(3)BaBi4 square pyramids,  an edgeedge with one Se(21)Ba4Bi square pyramid,  an edgeedge with one Se(3)BaBi4 square pyramid, edges with two equivalent Se(20)Ba2Bi3 square pyramids, edges with two equivalent Se(25)Ba2Bi3 trigonal bipyramids, and edges with two equivalent Se(8)Ba2Bi3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 42°. In the twenty-sixth Se site, Se(26) is bonded to two equivalent Ba(1), one Bi(6), and two equivalent Bi(7) atoms to form SeBa2Bi3 trigonal bipyramids that share corners with two equivalent Se(14)Ba2Bi3 square pyramids, corners with two equivalent Se(22)Ba4Bi square pyramids, corners with two equivalent Se(17)BaBi4 square pyramids, corners with two equivalent Se(4)BaBi4 square pyramids,  an edgeedge with one Se(14)Ba2Bi3 square pyramid,  an edgeedge with one Se(22)Ba4Bi square pyramid,  an edgeedge with one Se(4)BaBi4 square pyramid, edges with two equivalent Se(19)Ba2Bi3 square pyramids, edges with two equivalent Se(26)Ba2Bi3 trigonal bipyramids, and edges with two equivalent Se(7)Ba2Bi3 trigonal bipyramids.