Nd12Si5Se28 crystallizes in the triclinic P1 space group. There are twelve inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a 8-coordinate geometry to one Se(15), one Se(16), one Se(19), one Se(2), one Se(21), one Se(26), one Se(6), and one Se(8) atom. In the second Nd site, Nd(2) is bonded in a 8-coordinate geometry to one Se(1), one Se(15), one Se(16), one Se(20), one Se(22), one Se(25), one Se(5), and one Se(7) atom. In the third Nd site, Nd(3) is bonded in a 8-coordinate geometry to one Se(10), one Se(11), one Se(12), one Se(17), one Se(2), one Se(21), one Se(28), and one Se(7) atom. In the fourth Nd site, Nd(4) is bonded in a 8-coordinate geometry to one Se(1), one Se(11), one Se(12), one Se(18), one Se(22), one Se(27), one Se(8), and one Se(9) atom. In the fifth Nd site, Nd(5) is bonded in a 8-coordinate geometry to one Se(10), one Se(13), one Se(14), one Se(17), one Se(19), one Se(2), one Se(23), and one Se(5) atom. In the sixth Nd site, Nd(6) is bonded in a 8-coordinate geometry to one Se(1), one Se(13), one Se(14), one Se(18), one Se(20), one Se(24), one Se(6), and one Se(9) atom. In the seventh Nd site, Nd(7) is bonded in a 8-coordinate geometry to one Se(10), one Se(12), one Se(14), one Se(20), one Se(26), one Se(28), one Se(4), and one Se(9) atom. In the eighth Nd site, Nd(8) is bonded in a 8-coordinate geometry to one Se(10), one Se(11), one Se(13), one Se(19), one Se(25), one Se(27), one Se(3), and one Se(9) atom. In the ninth Nd site, Nd(9) is bonded in a 8-coordinate geometry to one Se(13), one Se(16), one Se(22), one Se(24), one Se(28), one Se(4), one Se(5), and one Se(6) atom. In the tenth Nd site, Nd(10) is bonded in a 8-coordinate geometry to one Se(14), one Se(15), one Se(21), one Se(23), one Se(27), one Se(3), one Se(5), and one Se(6) atom. In the eleventh Nd site, Nd(11) is bonded in a 8-coordinate geometry to one Se(11), one Se(16), one Se(17), one Se(24), one Se(26), one Se(4), one Se(7), and one Se(8) atom. In the twelfth Nd site, Nd(12) is bonded in a 8-coordinate geometry to one Se(12), one Se(15), one Se(18), one Se(23), one Se(25), one Se(3), one Se(7), and one Se(8) atom. There are five inequivalent Si sites. In the first Si site, Si(1) is bonded in a tetrahedral geometry to one Se(1), one Se(17), one Se(19), and one Se(21) atom. In the second Si site, Si(2) is bonded in a tetrahedral geometry to one Se(18), one Se(2), one Se(20), and one Se(22) atom. In the third Si site, Si(3) is bonded in a tetrahedral geometry to one Se(23), one Se(25), one Se(27), and one Se(4) atom. In the fourth Si site, Si(4) is bonded in a tetrahedral geometry to one Se(24), one Se(26), one Se(28), and one Se(3) atom. In the fifth Si site, Si(5) is bonded in an octahedral geometry to one Se(11), one Se(13), one Se(16), one Se(6), one Se(8), and one Se(9) atom. There are twenty-eight inequivalent Se sites. In the first Se site, Se(1) is bonded to one Nd(2), one Nd(4), one Nd(6), and one Si(1) atom to form SeNd3Si tetrahedra that share  a cornercorner with one Se(6)Nd4Si trigonal bipyramid,  a cornercorner with one Se(8)Nd4Si trigonal bipyramid, corners with two equivalent Se(9)Nd4Si trigonal bipyramids,  a cornercorner with one Se(21)Nd3Si trigonal pyramid,  a cornercorner with one Se(12)Nd4 trigonal pyramid,  a cornercorner with one Se(14)Nd4 trigonal pyramid,  a cornercorner with one Se(15)Nd4 trigonal pyramid,  a cornercorner with one Se(5)Nd4 trigonal pyramid, and  a cornercorner with one Se(7)Nd4 trigonal pyramid. In the second Se site, Se(2) is bonded to one Nd(1), one Nd(3), one Nd(5), and one Si(2) atom to form SeNd3Si tetrahedra that share  a cornercorner with one Se(6)Nd4Si trigonal bipyramid,  a cornercorner with one Se(8)Nd4Si trigonal bipyramid,  a cornercorner with one Se(12)Nd4 trigonal pyramid,  a cornercorner with one Se(14)Nd4 trigonal pyramid,  a cornercorner with one Se(15)Nd4 trigonal pyramid,  a cornercorner with one Se(5)Nd4 trigonal pyramid,  a cornercorner with one Se(7)Nd4 trigonal pyramid, corners with two equivalent Se(10)Nd4 trigonal pyramids, and  an edgeedge with one Se(21)Nd3Si trigonal pyramid. In the third Se site, Se(3) is bonded to one Nd(10), one Nd(12), one Nd(8), and one Si(4) atom to form distorted SeNd3Si tetrahedra that share  a cornercorner with one Se(6)Nd4Si trigonal bipyramid,  a cornercorner with one Se(8)Nd4Si trigonal bipyramid,  a cornercorner with one Se(9)Nd4Si trigonal bipyramid,  a cornercorner with one Se(21)Nd3Si trigonal pyramid,  a cornercorner with one Se(10)Nd4 trigonal pyramid,  a cornercorner with one Se(12)Nd4 trigonal pyramid,  a cornercorner with one Se(14)Nd4 trigonal pyramid,  a cornercorner with one Se(5)Nd4 trigonal pyramid,  a cornercorner with one Se(7)Nd4 trigonal pyramid, and corners with two equivalent Se(15)Nd4 trigonal pyramids. In the fourth Se site, Se(4) is bonded to one Nd(11), one Nd(7), one Nd(9), and one Si(3) atom to form distorted SeNd3Si tetrahedra that share  a cornercorner with one Se(6)Nd4Si trigonal bipyramid,  a cornercorner with one Se(8)Nd4Si trigonal bipyramid,  a cornercorner with one Se(9)Nd4Si trigonal bipyramid,  a cornercorner with one Se(10)Nd4 trigonal pyramid,  a cornercorner with one Se(12)Nd4 trigonal pyramid,  a cornercorner with one Se(14)Nd4 trigonal pyramid,  a cornercorner with one Se(5)Nd4 trigonal pyramid, and  a cornercorner with one Se(7)Nd4 trigonal pyramid. In the fifth Se site, Se(5) is bonded to one Nd(10), one Nd(2), one Nd(5), and one Nd(9) atom to form distorted SeNd4 trigonal pyramids that share  a cornercorner with one Se(1)Nd3Si tetrahedra,  a cornercorner with one Se(2)Nd3Si tetrahedra,  a cornercorner with one Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(4)Nd3Si tetrahedra, corners with two equivalent Se(6)Nd4Si trigonal bipyramids,  a cornercorner with one Se(21)Nd3Si trigonal pyramid,  a cornercorner with one Se(10)Nd4 trigonal pyramid,  a cornercorner with one Se(7)Nd4 trigonal pyramid,  an edgeedge with one Se(14)Nd4 trigonal pyramid, and  an edgeedge with one Se(15)Nd4 trigonal pyramid. In the sixth Se site, Se(6) is bonded to one Nd(1), one Nd(10), one Nd(6), one Nd(9), and one Si(5) atom to form distorted SeNd4Si trigonal bipyramids that share  a cornercorner with one Se(1)Nd3Si tetrahedra,  a cornercorner with one Se(2)Nd3Si tetrahedra,  a cornercorner with one Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(4)Nd3Si tetrahedra, corners with two equivalent Se(5)Nd4 trigonal pyramids,  an edgeedge with one Se(8)Nd4Si trigonal bipyramid,  an edgeedge with one Se(9)Nd4Si trigonal bipyramid,  an edgeedge with one Se(21)Nd3Si trigonal pyramid,  an edgeedge with one Se(14)Nd4 trigonal pyramid, and  an edgeedge with one Se(15)Nd4 trigonal pyramid. In the seventh Se site, Se(7) is bonded to one Nd(11), one Nd(12), one Nd(2), and one Nd(3) atom to form distorted SeNd4 trigonal pyramids that share  a cornercorner with one Se(1)Nd3Si tetrahedra,  a cornercorner with one Se(2)Nd3Si tetrahedra,  a cornercorner with one Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(4)Nd3Si tetrahedra, corners with two equivalent Se(8)Nd4Si trigonal bipyramids,  a cornercorner with one Se(21)Nd3Si trigonal pyramid,  a cornercorner with one Se(10)Nd4 trigonal pyramid,  a cornercorner with one Se(5)Nd4 trigonal pyramid,  an edgeedge with one Se(12)Nd4 trigonal pyramid, and  an edgeedge with one Se(15)Nd4 trigonal pyramid. In the eighth Se site, Se(8) is bonded to one Nd(1), one Nd(11), one Nd(12), one Nd(4), and one Si(5) atom to form distorted SeNd4Si trigonal bipyramids that share  a cornercorner with one Se(1)Nd3Si tetrahedra,  a cornercorner with one Se(2)Nd3Si tetrahedra,  a cornercorner with one Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(4)Nd3Si tetrahedra,  a cornercorner with one Se(21)Nd3Si trigonal pyramid, corners with two equivalent Se(7)Nd4 trigonal pyramids,  an edgeedge with one Se(6)Nd4Si trigonal bipyramid,  an edgeedge with one Se(9)Nd4Si trigonal bipyramid,  an edgeedge with one Se(12)Nd4 trigonal pyramid, and  an edgeedge with one Se(15)Nd4 trigonal pyramid. In the ninth Se site, Se(9) is bonded to one Nd(4), one Nd(6), one Nd(7), one Nd(8), and one Si(5) atom to form distorted SeNd4Si trigonal bipyramids that share  a cornercorner with one Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(4)Nd3Si tetrahedra, corners with two equivalent Se(1)Nd3Si tetrahedra, corners with two equivalent Se(10)Nd4 trigonal pyramids,  an edgeedge with one Se(6)Nd4Si trigonal bipyramid,  an edgeedge with one Se(8)Nd4Si trigonal bipyramid,  an edgeedge with one Se(12)Nd4 trigonal pyramid, and  an edgeedge with one Se(14)Nd4 trigonal pyramid. In the tenth Se site, Se(10) is bonded to one Nd(3), one Nd(5), one Nd(7), and one Nd(8) atom to form distorted SeNd4 trigonal pyramids that share  a cornercorner with one Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(4)Nd3Si tetrahedra, corners with two equivalent Se(2)Nd3Si tetrahedra, corners with two equivalent Se(9)Nd4Si trigonal bipyramids,  a cornercorner with one Se(21)Nd3Si trigonal pyramid,  a cornercorner with one Se(5)Nd4 trigonal pyramid,  a cornercorner with one Se(7)Nd4 trigonal pyramid,  an edgeedge with one Se(12)Nd4 trigonal pyramid, and  an edgeedge with one Se(14)Nd4 trigonal pyramid. In the eleventh Se site, Se(11) is bonded in a 5-coordinate geometry to one Nd(11), one Nd(3), one Nd(4), one Nd(8), and one Si(5) atom. In the twelfth Se site, Se(12) is bonded to one Nd(12), one Nd(3), one Nd(4), and one Nd(7) atom to form distorted SeNd4 trigonal pyramids that share  a cornercorner with one Se(1)Nd3Si tetrahedra,  a cornercorner with one Se(2)Nd3Si tetrahedra,  a cornercorner with one Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(4)Nd3Si tetrahedra,  a cornercorner with one Se(21)Nd3Si trigonal pyramid,  a cornercorner with one Se(14)Nd4 trigonal pyramid,  a cornercorner with one Se(15)Nd4 trigonal pyramid,  an edgeedge with one Se(8)Nd4Si trigonal bipyramid,  an edgeedge with one Se(9)Nd4Si trigonal bipyramid,  an edgeedge with one Se(10)Nd4 trigonal pyramid, and  an edgeedge with one Se(7)Nd4 trigonal pyramid. In the thirteenth Se site, Se(13) is bonded in a 5-coordinate geometry to one Nd(5), one Nd(6), one Nd(8), one Nd(9), and one Si(5) atom. In the fourteenth Se site, Se(14) is bonded to one Nd(10), one Nd(5), one Nd(6), and one Nd(7) atom to form distorted SeNd4 trigonal pyramids that share  a cornercorner with one Se(1)Nd3Si tetrahedra,  a cornercorner with one Se(2)Nd3Si tetrahedra,  a cornercorner with one Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(4)Nd3Si tetrahedra,  a cornercorner with one Se(21)Nd3Si trigonal pyramid,  a cornercorner with one Se(12)Nd4 trigonal pyramid,  a cornercorner with one Se(15)Nd4 trigonal pyramid,  an edgeedge with one Se(6)Nd4Si trigonal bipyramid,  an edgeedge with one Se(9)Nd4Si trigonal bipyramid,  an edgeedge with one Se(10)Nd4 trigonal pyramid, and  an edgeedge with one Se(5)Nd4 trigonal pyramid. In the fifteenth Se site, Se(15) is bonded to one Nd(1), one Nd(10), one Nd(12), and one Nd(2) atom to form distorted SeNd4 trigonal pyramids that share  a cornercorner with one Se(1)Nd3Si tetrahedra,  a cornercorner with one Se(2)Nd3Si tetrahedra, corners with two equivalent Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(12)Nd4 trigonal pyramid,  a cornercorner with one Se(14)Nd4 trigonal pyramid,  an edgeedge with one Se(6)Nd4Si trigonal bipyramid,  an edgeedge with one Se(8)Nd4Si trigonal bipyramid,  an edgeedge with one Se(21)Nd3Si trigonal pyramid,  an edgeedge with one Se(5)Nd4 trigonal pyramid, and  an edgeedge with one Se(7)Nd4 trigonal pyramid. In the sixteenth Se site, Se(16) is bonded in a 5-coordinate geometry to one Nd(1), one Nd(11), one Nd(2), one Nd(9), and one Si(5) atom. In the seventeenth Se site, Se(17) is bonded in a distorted rectangular see-saw-like geometry to one Nd(11), one Nd(3), one Nd(5), and one Si(1) atom. In the eighteenth Se site, Se(18) is bonded in a distorted rectangular see-saw-like geometry to one Nd(12), one Nd(4), one Nd(6), and one Si(2) atom. In the nineteenth Se site, Se(19) is bonded in a distorted rectangular see-saw-like geometry to one Nd(1), one Nd(5), one Nd(8), and one Si(1) atom. In the twentieth Se site, Se(20) is bonded in a distorted rectangular see-saw-like geometry to one Nd(2), one Nd(6), one Nd(7), and one Si(2) atom. In the twenty-first Se site, Se(21) is bonded to one Nd(1), one Nd(10), one Nd(3), and one Si(1) atom to form distorted SeNd3Si trigonal pyramids that share  a cornercorner with one Se(1)Nd3Si tetrahedra,  a cornercorner with one Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(8)Nd4Si trigonal bipyramid,  a cornercorner with one Se(10)Nd4 trigonal pyramid,  a cornercorner with one Se(12)Nd4 trigonal pyramid,  a cornercorner with one Se(14)Nd4 trigonal pyramid,  a cornercorner with one Se(5)Nd4 trigonal pyramid,  a cornercorner with one Se(7)Nd4 trigonal pyramid,  an edgeedge with one Se(2)Nd3Si tetrahedra,  an edgeedge with one Se(6)Nd4Si trigonal bipyramid, and  an edgeedge with one Se(15)Nd4 trigonal pyramid. In the twenty-second Se site, Se(22) is bonded in a distorted rectangular see-saw-like geometry to one Nd(2), one Nd(4), one Nd(9), and one Si(2) atom. In the twenty-third Se site, Se(23) is bonded in a distorted rectangular see-saw-like geometry to one Nd(10), one Nd(12), one Nd(5), and one Si(3) atom. In the twenty-fourth Se site, Se(24) is bonded in a distorted rectangular see-saw-like geometry to one Nd(11), one Nd(6), one Nd(9), and one Si(4) atom. In the twenty-fifth Se site, Se(25) is bonded in a distorted rectangular see-saw-like geometry to one Nd(12), one Nd(2), one Nd(8), and one Si(3) atom. In the twenty-sixth Se site, Se(26) is bonded in a distorted rectangular see-saw-like geometry to one Nd(1), one Nd(11), one Nd(7), and one Si(4) atom. In the twenty-seventh Se site, Se(27) is bonded in a distorted rectangular see-saw-like geometry to one Nd(10), one Nd(4), one Nd(8), and one Si(3) atom. In the twenty-eighth Se site, Se(28) is bonded in a distorted rectangular see-saw-like geometry to one Nd(3), one Nd(7), one Nd(9), and one Si(4) atom.
Nd12Si5Se28 crystallizes in the triclinic P1 space group. There are twelve inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a 8-coordinate geometry to one Se(15), one Se(16), one Se(19), one Se(2), one Se(21), one Se(26), one Se(6), and one Se(8) atom. The Nd(1)-Se(15) bond length is 3.13 Å. The Nd(1)-Se(16) bond length is 3.08 Å. The Nd(1)-Se(19) bond length is 2.99 Å. The Nd(1)-Se(2) bond length is 3.14 Å. The Nd(1)-Se(21) bond length is 3.12 Å. The Nd(1)-Se(26) bond length is 3.20 Å. The Nd(1)-Se(6) bond length is 2.97 Å. The Nd(1)-Se(8) bond length is 3.01 Å. In the second Nd site, Nd(2) is bonded in a 8-coordinate geometry to one Se(1), one Se(15), one Se(16), one Se(20), one Se(22), one Se(25), one Se(5), and one Se(7) atom. The Nd(2)-Se(1) bond length is 3.19 Å. The Nd(2)-Se(15) bond length is 2.95 Å. The Nd(2)-Se(16) bond length is 3.69 Å. The Nd(2)-Se(20) bond length is 3.09 Å. The Nd(2)-Se(22) bond length is 3.09 Å. The Nd(2)-Se(25) bond length is 3.19 Å. The Nd(2)-Se(5) bond length is 2.92 Å. The Nd(2)-Se(7) bond length is 2.91 Å. In the third Nd site, Nd(3) is bonded in a 8-coordinate geometry to one Se(10), one Se(11), one Se(12), one Se(17), one Se(2), one Se(21), one Se(28), and one Se(7) atom. The Nd(3)-Se(10) bond length is 2.94 Å. The Nd(3)-Se(11) bond length is 3.66 Å. The Nd(3)-Se(12) bond length is 2.95 Å. The Nd(3)-Se(17) bond length is 3.19 Å. The Nd(3)-Se(2) bond length is 3.18 Å. The Nd(3)-Se(21) bond length is 3.07 Å. The Nd(3)-Se(28) bond length is 3.20 Å. The Nd(3)-Se(7) bond length is 2.91 Å. In the fourth Nd site, Nd(4) is bonded in a 8-coordinate geometry to one Se(1), one Se(11), one Se(12), one Se(18), one Se(22), one Se(27), one Se(8), and one Se(9) atom. The Nd(4)-Se(1) bond length is 3.15 Å. The Nd(4)-Se(11) bond length is 3.08 Å. The Nd(4)-Se(12) bond length is 3.16 Å. The Nd(4)-Se(18) bond length is 3.04 Å. The Nd(4)-Se(22) bond length is 3.00 Å. The Nd(4)-Se(27) bond length is 3.18 Å. The Nd(4)-Se(8) bond length is 2.99 Å. The Nd(4)-Se(9) bond length is 2.98 Å. In the fifth Nd site, Nd(5) is bonded in a 8-coordinate geometry to one Se(10), one Se(13), one Se(14), one Se(17), one Se(19), one Se(2), one Se(23), and one Se(5) atom. The Nd(5)-Se(10) bond length is 2.94 Å. The Nd(5)-Se(13) bond length is 3.68 Å. The Nd(5)-Se(14) bond length is 2.96 Å. The Nd(5)-Se(17) bond length is 3.12 Å. The Nd(5)-Se(19) bond length is 3.09 Å. The Nd(5)-Se(2) bond length is 3.18 Å. The Nd(5)-Se(23) bond length is 3.18 Å. The Nd(5)-Se(5) bond length is 2.92 Å. In the sixth Nd site, Nd(6) is bonded in a 8-coordinate geometry to one Se(1), one Se(13), one Se(14), one Se(18), one Se(20), one Se(24), one Se(6), and one Se(9) atom. The Nd(6)-Se(1) bond length is 3.15 Å. The Nd(6)-Se(13) bond length is 3.06 Å. The Nd(6)-Se(14) bond length is 3.15 Å. The Nd(6)-Se(18) bond length is 2.96 Å. The Nd(6)-Se(20) bond length is 3.11 Å. The Nd(6)-Se(24) bond length is 3.22 Å. The Nd(6)-Se(6) bond length is 3.00 Å. The Nd(6)-Se(9) bond length is 2.95 Å. In the seventh Nd site, Nd(7) is bonded in a 8-coordinate geometry to one Se(10), one Se(12), one Se(14), one Se(20), one Se(26), one Se(28), one Se(4), and one Se(9) atom. The Nd(7)-Se(10) bond length is 3.17 Å. The Nd(7)-Se(12) bond length is 2.90 Å. The Nd(7)-Se(14) bond length is 2.90 Å. The Nd(7)-Se(20) bond length is 3.26 Å. The Nd(7)-Se(26) bond length is 3.05 Å. The Nd(7)-Se(28) bond length is 3.13 Å. The Nd(7)-Se(4) bond length is 3.19 Å. The Nd(7)-Se(9) bond length is 3.29 Å. In the eighth Nd site, Nd(8) is bonded in a 8-coordinate geometry to one Se(10), one Se(11), one Se(13), one Se(19), one Se(25), one Se(27), one Se(3), and one Se(9) atom. The Nd(8)-Se(10) bond length is 3.00 Å. The Nd(8)-Se(11) bond length is 3.02 Å. The Nd(8)-Se(13) bond length is 3.00 Å. The Nd(8)-Se(19) bond length is 3.13 Å. The Nd(8)-Se(25) bond length is 2.98 Å. The Nd(8)-Se(27) bond length is 3.06 Å. The Nd(8)-Se(3) bond length is 3.14 Å. The Nd(8)-Se(9) bond length is 3.34 Å. In the ninth Nd site, Nd(9) is bonded in a 8-coordinate geometry to one Se(13), one Se(16), one Se(22), one Se(24), one Se(28), one Se(4), one Se(5), and one Se(6) atom. The Nd(9)-Se(13) bond length is 3.02 Å. The Nd(9)-Se(16) bond length is 3.00 Å. The Nd(9)-Se(22) bond length is 3.11 Å. The Nd(9)-Se(24) bond length is 3.08 Å. The Nd(9)-Se(28) bond length is 2.99 Å. The Nd(9)-Se(4) bond length is 3.11 Å. The Nd(9)-Se(5) bond length is 3.01 Å. The Nd(9)-Se(6) bond length is 3.33 Å. In the tenth Nd site, Nd(10) is bonded in a 8-coordinate geometry to one Se(14), one Se(15), one Se(21), one Se(23), one Se(27), one Se(3), one Se(5), and one Se(6) atom. The Nd(10)-Se(14) bond length is 2.91 Å. The Nd(10)-Se(15) bond length is 2.91 Å. The Nd(10)-Se(21) bond length is 3.28 Å. The Nd(10)-Se(23) bond length is 3.10 Å. The Nd(10)-Se(27) bond length is 3.03 Å. The Nd(10)-Se(3) bond length is 3.24 Å. The Nd(10)-Se(5) bond length is 3.19 Å. The Nd(10)-Se(6) bond length is 3.26 Å. In the eleventh Nd site, Nd(11) is bonded in a 8-coordinate geometry to one Se(11), one Se(16), one Se(17), one Se(24), one Se(26), one Se(4), one Se(7), and one Se(8) atom. The Nd(11)-Se(11) bond length is 2.99 Å. The Nd(11)-Se(16) bond length is 3.03 Å. The Nd(11)-Se(17) bond length is 3.14 Å. The Nd(11)-Se(24) bond length is 3.00 Å. The Nd(11)-Se(26) bond length is 3.07 Å. The Nd(11)-Se(4) bond length is 3.13 Å. The Nd(11)-Se(7) bond length is 3.00 Å. The Nd(11)-Se(8) bond length is 3.34 Å. In the twelfth Nd site, Nd(12) is bonded in a 8-coordinate geometry to one Se(12), one Se(15), one Se(18), one Se(23), one Se(25), one Se(3), one Se(7), and one Se(8) atom. The Nd(12)-Se(12) bond length is 2.92 Å. The Nd(12)-Se(15) bond length is 2.91 Å. The Nd(12)-Se(18) bond length is 3.22 Å. The Nd(12)-Se(23) bond length is 3.03 Å. The Nd(12)-Se(25) bond length is 3.12 Å. The Nd(12)-Se(3) bond length is 3.23 Å. The Nd(12)-Se(7) bond length is 3.18 Å. The Nd(12)-Se(8) bond length is 3.28 Å. There are five inequivalent Si sites. In the first Si site, Si(1) is bonded in a tetrahedral geometry to one Se(1), one Se(17), one Se(19), and one Se(21) atom. The Si(1)-Se(1) bond length is 2.27 Å. The Si(1)-Se(17) bond length is 2.30 Å. The Si(1)-Se(19) bond length is 2.31 Å. The Si(1)-Se(21) bond length is 2.31 Å. In the second Si site, Si(2) is bonded in a tetrahedral geometry to one Se(18), one Se(2), one Se(20), and one Se(22) atom. The Si(2)-Se(18) bond length is 2.32 Å. The Si(2)-Se(2) bond length is 2.27 Å. The Si(2)-Se(20) bond length is 2.31 Å. The Si(2)-Se(22) bond length is 2.30 Å. In the third Si site, Si(3) is bonded in a tetrahedral geometry to one Se(23), one Se(25), one Se(27), and one Se(4) atom. The Si(3)-Se(23) bond length is 2.30 Å. The Si(3)-Se(25) bond length is 2.30 Å. The Si(3)-Se(27) bond length is 2.31 Å. The Si(3)-Se(4) bond length is 2.28 Å. In the fourth Si site, Si(4) is bonded in a tetrahedral geometry to one Se(24), one Se(26), one Se(28), and one Se(3) atom. The Si(4)-Se(24) bond length is 2.31 Å. The Si(4)-Se(26) bond length is 2.31 Å. The Si(4)-Se(28) bond length is 2.30 Å. The Si(4)-Se(3) bond length is 2.27 Å. In the fifth Si site, Si(5) is bonded in an octahedral geometry to one Se(11), one Se(13), one Se(16), one Se(6), one Se(8), and one Se(9) atom. The Si(5)-Se(11) bond length is 2.52 Å. The Si(5)-Se(13) bond length is 2.51 Å. The Si(5)-Se(16) bond length is 2.50 Å. The Si(5)-Se(6) bond length is 2.59 Å. The Si(5)-Se(8) bond length is 2.57 Å. The Si(5)-Se(9) bond length is 2.59 Å. There are twenty-eight inequivalent Se sites. In the first Se site, Se(1) is bonded to one Nd(2), one Nd(4), one Nd(6), and one Si(1) atom to form SeNd3Si tetrahedra that share  a cornercorner with one Se(6)Nd4Si trigonal bipyramid,  a cornercorner with one Se(8)Nd4Si trigonal bipyramid, corners with two equivalent Se(9)Nd4Si trigonal bipyramids,  a cornercorner with one Se(21)Nd3Si trigonal pyramid,  a cornercorner with one Se(12)Nd4 trigonal pyramid,  a cornercorner with one Se(14)Nd4 trigonal pyramid,  a cornercorner with one Se(15)Nd4 trigonal pyramid,  a cornercorner with one Se(5)Nd4 trigonal pyramid, and  a cornercorner with one Se(7)Nd4 trigonal pyramid. In the second Se site, Se(2) is bonded to one Nd(1), one Nd(3), one Nd(5), and one Si(2) atom to form SeNd3Si tetrahedra that share  a cornercorner with one Se(6)Nd4Si trigonal bipyramid,  a cornercorner with one Se(8)Nd4Si trigonal bipyramid,  a cornercorner with one Se(12)Nd4 trigonal pyramid,  a cornercorner with one Se(14)Nd4 trigonal pyramid,  a cornercorner with one Se(15)Nd4 trigonal pyramid,  a cornercorner with one Se(5)Nd4 trigonal pyramid,  a cornercorner with one Se(7)Nd4 trigonal pyramid, corners with two equivalent Se(10)Nd4 trigonal pyramids, and  an edgeedge with one Se(21)Nd3Si trigonal pyramid. In the third Se site, Se(3) is bonded to one Nd(10), one Nd(12), one Nd(8), and one Si(4) atom to form distorted SeNd3Si tetrahedra that share  a cornercorner with one Se(6)Nd4Si trigonal bipyramid,  a cornercorner with one Se(8)Nd4Si trigonal bipyramid,  a cornercorner with one Se(9)Nd4Si trigonal bipyramid,  a cornercorner with one Se(21)Nd3Si trigonal pyramid,  a cornercorner with one Se(10)Nd4 trigonal pyramid,  a cornercorner with one Se(12)Nd4 trigonal pyramid,  a cornercorner with one Se(14)Nd4 trigonal pyramid,  a cornercorner with one Se(5)Nd4 trigonal pyramid,  a cornercorner with one Se(7)Nd4 trigonal pyramid, and corners with two equivalent Se(15)Nd4 trigonal pyramids. In the fourth Se site, Se(4) is bonded to one Nd(11), one Nd(7), one Nd(9), and one Si(3) atom to form distorted SeNd3Si tetrahedra that share  a cornercorner with one Se(6)Nd4Si trigonal bipyramid,  a cornercorner with one Se(8)Nd4Si trigonal bipyramid,  a cornercorner with one Se(9)Nd4Si trigonal bipyramid,  a cornercorner with one Se(10)Nd4 trigonal pyramid,  a cornercorner with one Se(12)Nd4 trigonal pyramid,  a cornercorner with one Se(14)Nd4 trigonal pyramid,  a cornercorner with one Se(5)Nd4 trigonal pyramid, and  a cornercorner with one Se(7)Nd4 trigonal pyramid. In the fifth Se site, Se(5) is bonded to one Nd(10), one Nd(2), one Nd(5), and one Nd(9) atom to form distorted SeNd4 trigonal pyramids that share  a cornercorner with one Se(1)Nd3Si tetrahedra,  a cornercorner with one Se(2)Nd3Si tetrahedra,  a cornercorner with one Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(4)Nd3Si tetrahedra, corners with two equivalent Se(6)Nd4Si trigonal bipyramids,  a cornercorner with one Se(21)Nd3Si trigonal pyramid,  a cornercorner with one Se(10)Nd4 trigonal pyramid,  a cornercorner with one Se(7)Nd4 trigonal pyramid,  an edgeedge with one Se(14)Nd4 trigonal pyramid, and  an edgeedge with one Se(15)Nd4 trigonal pyramid. In the sixth Se site, Se(6) is bonded to one Nd(1), one Nd(10), one Nd(6), one Nd(9), and one Si(5) atom to form distorted SeNd4Si trigonal bipyramids that share  a cornercorner with one Se(1)Nd3Si tetrahedra,  a cornercorner with one Se(2)Nd3Si tetrahedra,  a cornercorner with one Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(4)Nd3Si tetrahedra, corners with two equivalent Se(5)Nd4 trigonal pyramids,  an edgeedge with one Se(8)Nd4Si trigonal bipyramid,  an edgeedge with one Se(9)Nd4Si trigonal bipyramid,  an edgeedge with one Se(21)Nd3Si trigonal pyramid,  an edgeedge with one Se(14)Nd4 trigonal pyramid, and  an edgeedge with one Se(15)Nd4 trigonal pyramid. In the seventh Se site, Se(7) is bonded to one Nd(11), one Nd(12), one Nd(2), and one Nd(3) atom to form distorted SeNd4 trigonal pyramids that share  a cornercorner with one Se(1)Nd3Si tetrahedra,  a cornercorner with one Se(2)Nd3Si tetrahedra,  a cornercorner with one Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(4)Nd3Si tetrahedra, corners with two equivalent Se(8)Nd4Si trigonal bipyramids,  a cornercorner with one Se(21)Nd3Si trigonal pyramid,  a cornercorner with one Se(10)Nd4 trigonal pyramid,  a cornercorner with one Se(5)Nd4 trigonal pyramid,  an edgeedge with one Se(12)Nd4 trigonal pyramid, and  an edgeedge with one Se(15)Nd4 trigonal pyramid. In the eighth Se site, Se(8) is bonded to one Nd(1), one Nd(11), one Nd(12), one Nd(4), and one Si(5) atom to form distorted SeNd4Si trigonal bipyramids that share  a cornercorner with one Se(1)Nd3Si tetrahedra,  a cornercorner with one Se(2)Nd3Si tetrahedra,  a cornercorner with one Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(4)Nd3Si tetrahedra,  a cornercorner with one Se(21)Nd3Si trigonal pyramid, corners with two equivalent Se(7)Nd4 trigonal pyramids,  an edgeedge with one Se(6)Nd4Si trigonal bipyramid,  an edgeedge with one Se(9)Nd4Si trigonal bipyramid,  an edgeedge with one Se(12)Nd4 trigonal pyramid, and  an edgeedge with one Se(15)Nd4 trigonal pyramid. In the ninth Se site, Se(9) is bonded to one Nd(4), one Nd(6), one Nd(7), one Nd(8), and one Si(5) atom to form distorted SeNd4Si trigonal bipyramids that share  a cornercorner with one Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(4)Nd3Si tetrahedra, corners with two equivalent Se(1)Nd3Si tetrahedra, corners with two equivalent Se(10)Nd4 trigonal pyramids,  an edgeedge with one Se(6)Nd4Si trigonal bipyramid,  an edgeedge with one Se(8)Nd4Si trigonal bipyramid,  an edgeedge with one Se(12)Nd4 trigonal pyramid, and  an edgeedge with one Se(14)Nd4 trigonal pyramid. In the tenth Se site, Se(10) is bonded to one Nd(3), one Nd(5), one Nd(7), and one Nd(8) atom to form distorted SeNd4 trigonal pyramids that share  a cornercorner with one Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(4)Nd3Si tetrahedra, corners with two equivalent Se(2)Nd3Si tetrahedra, corners with two equivalent Se(9)Nd4Si trigonal bipyramids,  a cornercorner with one Se(21)Nd3Si trigonal pyramid,  a cornercorner with one Se(5)Nd4 trigonal pyramid,  a cornercorner with one Se(7)Nd4 trigonal pyramid,  an edgeedge with one Se(12)Nd4 trigonal pyramid, and  an edgeedge with one Se(14)Nd4 trigonal pyramid. In the eleventh Se site, Se(11) is bonded in a 5-coordinate geometry to one Nd(11), one Nd(3), one Nd(4), one Nd(8), and one Si(5) atom. In the twelfth Se site, Se(12) is bonded to one Nd(12), one Nd(3), one Nd(4), and one Nd(7) atom to form distorted SeNd4 trigonal pyramids that share  a cornercorner with one Se(1)Nd3Si tetrahedra,  a cornercorner with one Se(2)Nd3Si tetrahedra,  a cornercorner with one Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(4)Nd3Si tetrahedra,  a cornercorner with one Se(21)Nd3Si trigonal pyramid,  a cornercorner with one Se(14)Nd4 trigonal pyramid,  a cornercorner with one Se(15)Nd4 trigonal pyramid,  an edgeedge with one Se(8)Nd4Si trigonal bipyramid,  an edgeedge with one Se(9)Nd4Si trigonal bipyramid,  an edgeedge with one Se(10)Nd4 trigonal pyramid, and  an edgeedge with one Se(7)Nd4 trigonal pyramid. In the thirteenth Se site, Se(13) is bonded in a 5-coordinate geometry to one Nd(5), one Nd(6), one Nd(8), one Nd(9), and one Si(5) atom. In the fourteenth Se site, Se(14) is bonded to one Nd(10), one Nd(5), one Nd(6), and one Nd(7) atom to form distorted SeNd4 trigonal pyramids that share  a cornercorner with one Se(1)Nd3Si tetrahedra,  a cornercorner with one Se(2)Nd3Si tetrahedra,  a cornercorner with one Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(4)Nd3Si tetrahedra,  a cornercorner with one Se(21)Nd3Si trigonal pyramid,  a cornercorner with one Se(12)Nd4 trigonal pyramid,  a cornercorner with one Se(15)Nd4 trigonal pyramid,  an edgeedge with one Se(6)Nd4Si trigonal bipyramid,  an edgeedge with one Se(9)Nd4Si trigonal bipyramid,  an edgeedge with one Se(10)Nd4 trigonal pyramid, and  an edgeedge with one Se(5)Nd4 trigonal pyramid. In the fifteenth Se site, Se(15) is bonded to one Nd(1), one Nd(10), one Nd(12), and one Nd(2) atom to form distorted SeNd4 trigonal pyramids that share  a cornercorner with one Se(1)Nd3Si tetrahedra,  a cornercorner with one Se(2)Nd3Si tetrahedra, corners with two equivalent Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(12)Nd4 trigonal pyramid,  a cornercorner with one Se(14)Nd4 trigonal pyramid,  an edgeedge with one Se(6)Nd4Si trigonal bipyramid,  an edgeedge with one Se(8)Nd4Si trigonal bipyramid,  an edgeedge with one Se(21)Nd3Si trigonal pyramid,  an edgeedge with one Se(5)Nd4 trigonal pyramid, and  an edgeedge with one Se(7)Nd4 trigonal pyramid. In the sixteenth Se site, Se(16) is bonded in a 5-coordinate geometry to one Nd(1), one Nd(11), one Nd(2), one Nd(9), and one Si(5) atom. In the seventeenth Se site, Se(17) is bonded in a distorted rectangular see-saw-like geometry to one Nd(11), one Nd(3), one Nd(5), and one Si(1) atom. In the eighteenth Se site, Se(18) is bonded in a distorted rectangular see-saw-like geometry to one Nd(12), one Nd(4), one Nd(6), and one Si(2) atom. In the nineteenth Se site, Se(19) is bonded in a distorted rectangular see-saw-like geometry to one Nd(1), one Nd(5), one Nd(8), and one Si(1) atom. In the twentieth Se site, Se(20) is bonded in a distorted rectangular see-saw-like geometry to one Nd(2), one Nd(6), one Nd(7), and one Si(2) atom. In the twenty-first Se site, Se(21) is bonded to one Nd(1), one Nd(10), one Nd(3), and one Si(1) atom to form distorted SeNd3Si trigonal pyramids that share  a cornercorner with one Se(1)Nd3Si tetrahedra,  a cornercorner with one Se(3)Nd3Si tetrahedra,  a cornercorner with one Se(8)Nd4Si trigonal bipyramid,  a cornercorner with one Se(10)Nd4 trigonal pyramid,  a cornercorner with one Se(12)Nd4 trigonal pyramid,  a cornercorner with one Se(14)Nd4 trigonal pyramid,  a cornercorner with one Se(5)Nd4 trigonal pyramid,  a cornercorner with one Se(7)Nd4 trigonal pyramid,  an edgeedge with one Se(2)Nd3Si tetrahedra,  an edgeedge with one Se(6)Nd4Si trigonal bipyramid, and  an edgeedge with one Se(15)Nd4 trigonal pyramid. In the twenty-second Se site, Se(22) is bonded in a distorted rectangular see-saw-like geometry to one Nd(2), one Nd(4), one Nd(9), and one Si(2) atom. In the twenty-third Se site, Se(23) is bonded in a distorted rectangular see-saw-like geometry to one Nd(10), one Nd(12), one Nd(5), and one Si(3) atom. In the twenty-fourth Se site, Se(24) is bonded in a distorted rectangular see-saw-like geometry to one Nd(11), one Nd(6), one Nd(9), and one Si(4) atom. In the twenty-fifth Se site, Se(25) is bonded in a distorted rectangular see-saw-like geometry to one Nd(12), one Nd(2), one Nd(8), and one Si(3) atom. In the twenty-sixth Se site, Se(26) is bonded in a distorted rectangular see-saw-like geometry to one Nd(1), one Nd(11), one Nd(7), and one Si(4) atom. In the twenty-seventh Se site, Se(27) is bonded in a distorted rectangular see-saw-like geometry to one Nd(10), one Nd(4), one Nd(8), and one Si(3) atom. In the twenty-eighth Se site, Se(28) is bonded in a distorted rectangular see-saw-like geometry to one Nd(3), one Nd(7), one Nd(9), and one Si(4) atom.