Ti19Se20 crystallizes in the triclinic P-1 space group. There are eleven inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one Se(10), one Se(2), one Se(3), one Se(5), one Se(7), and one Se(8) atom to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 42-45°. In the second Ti site, Ti(2) is bonded to one Se(1), one Se(10), one Se(2), one Se(4), one Se(5), and one Se(9) atom to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 42-50°. In the third Ti site, Ti(3) is bonded to one Se(2), one Se(6), one Se(8), one Se(9), and two equivalent Se(4) atoms to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 43-47°. In the fourth Ti site, Ti(4) is bonded to one Se(1), one Se(10), one Se(2), one Se(3), one Se(6), and one Se(7) atom to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 42-50°. In the fifth Ti site, Ti(5) is bonded to one Se(4), one Se(6), one Se(7), one Se(8), and two equivalent Se(9) atoms to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 43-48°. In the sixth Ti site, Ti(6) is bonded to one Se(1), one Se(3), one Se(4), one Se(5), one Se(7), and one Se(9) atom to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 42-50°. In the seventh Ti site, Ti(7) is bonded to one Se(10), one Se(3), one Se(4), one Se(6), and two equivalent Se(8) atoms to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 43-48°. In the eighth Ti site, Ti(8) is bonded to one Se(10), one Se(3), one Se(8), one Se(9), and two equivalent Se(6) atoms to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 42-47°. In the ninth Ti site, Ti(9) is bonded to two equivalent Se(1), two equivalent Se(10), and two equivalent Se(5) atoms to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 45-48°. In the tenth Ti site, Ti(10) is bonded to two equivalent Se(1), two equivalent Se(3), and two equivalent Se(5) atoms to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 46-48°. In the eleventh Ti site, Ti(11) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(7) atoms to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 45-46°. There are ten inequivalent Se sites. In the first Se site, Se(1) is bonded to one Ti(10), one Ti(11), one Ti(2), one Ti(4), one Ti(6), and one Ti(9) atom to form distorted SeTi6 pentagonal pyramids that share  a cornercorner with one Se(6)Ti6 pentagonal pyramid, corners with two equivalent Se(9)Ti6 pentagonal pyramids, corners with three equivalent Se(1)Ti6 pentagonal pyramids,  an edgeedge with one Se(4)Ti6 pentagonal pyramid, edges with two equivalent Se(10)Ti6 pentagonal pyramids, edges with two equivalent Se(3)Ti6 pentagonal pyramids, and edges with three equivalent Se(5)Ti5 trigonal bipyramids. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to one Ti(1), one Ti(11), one Ti(2), one Ti(3), and one Ti(4) atom. In the third Se site, Se(3) is bonded to one Ti(1), one Ti(10), one Ti(4), one Ti(6), one Ti(7), and one Ti(8) atom to form distorted SeTi6 pentagonal pyramids that share  a cornercorner with one Se(3)Ti6 pentagonal pyramid, corners with two equivalent Se(6)Ti6 pentagonal pyramids,  an edgeedge with one Se(4)Ti6 pentagonal pyramid,  an edgeedge with one Se(6)Ti6 pentagonal pyramid,  an edgeedge with one Se(9)Ti6 pentagonal pyramid, edges with two equivalent Se(1)Ti6 pentagonal pyramids, edges with two equivalent Se(10)Ti6 pentagonal pyramids, edges with two equivalent Se(8)Ti6 pentagonal pyramids, and edges with two equivalent Se(5)Ti5 trigonal bipyramids. In the fourth Se site, Se(4) is bonded to one Ti(2), one Ti(5), one Ti(6), one Ti(7), and two equivalent Ti(3) atoms to form distorted SeTi6 pentagonal pyramids that share corners with three equivalent Se(8)Ti6 pentagonal pyramids, corners with two equivalent Se(5)Ti5 trigonal bipyramids,  an edgeedge with one Se(1)Ti6 pentagonal pyramid,  an edgeedge with one Se(10)Ti6 pentagonal pyramid,  an edgeedge with one Se(3)Ti6 pentagonal pyramid,  an edgeedge with one Se(4)Ti6 pentagonal pyramid,  an edgeedge with one Se(8)Ti6 pentagonal pyramid, edges with two equivalent Se(6)Ti6 pentagonal pyramids, and edges with three equivalent Se(9)Ti6 pentagonal pyramids. In the fifth Se site, Se(5) is bonded to one Ti(1), one Ti(10), one Ti(2), one Ti(6), and one Ti(9) atom to form distorted SeTi5 trigonal bipyramids that share  a cornercorner with one Se(8)Ti6 pentagonal pyramid, corners with two equivalent Se(4)Ti6 pentagonal pyramids, corners with two equivalent Se(5)Ti5 trigonal bipyramids,  an edgeedge with one Se(9)Ti6 pentagonal pyramid, edges with two equivalent Se(10)Ti6 pentagonal pyramids, edges with two equivalent Se(3)Ti6 pentagonal pyramids, and edges with three equivalent Se(1)Ti6 pentagonal pyramids. In the sixth Se site, Se(6) is bonded to one Ti(3), one Ti(4), one Ti(5), one Ti(7), and two equivalent Ti(8) atoms to form a mixture of distorted corner and edge-sharing SeTi6 pentagonal pyramids. In the seventh Se site, Se(7) is bonded in a 5-coordinate geometry to one Ti(1), one Ti(11), one Ti(4), one Ti(5), and one Ti(6) atom. In the eighth Se site, Se(8) is bonded to one Ti(1), one Ti(3), one Ti(5), one Ti(8), and two equivalent Ti(7) atoms to form distorted SeTi6 pentagonal pyramids that share corners with two equivalent Se(10)Ti6 pentagonal pyramids, corners with three equivalent Se(4)Ti6 pentagonal pyramids,  a cornercorner with one Se(5)Ti5 trigonal bipyramid,  an edgeedge with one Se(10)Ti6 pentagonal pyramid,  an edgeedge with one Se(4)Ti6 pentagonal pyramid,  an edgeedge with one Se(8)Ti6 pentagonal pyramid, edges with two equivalent Se(3)Ti6 pentagonal pyramids, edges with two equivalent Se(9)Ti6 pentagonal pyramids, and edges with three equivalent Se(6)Ti6 pentagonal pyramids. In the ninth Se site, Se(9) is bonded to one Ti(2), one Ti(3), one Ti(6), one Ti(8), and two equivalent Ti(5) atoms to form distorted SeTi6 pentagonal pyramids that share corners with two equivalent Se(1)Ti6 pentagonal pyramids, corners with three equivalent Se(6)Ti6 pentagonal pyramids,  an edgeedge with one Se(10)Ti6 pentagonal pyramid,  an edgeedge with one Se(3)Ti6 pentagonal pyramid,  an edgeedge with one Se(6)Ti6 pentagonal pyramid,  an edgeedge with one Se(9)Ti6 pentagonal pyramid, edges with two equivalent Se(8)Ti6 pentagonal pyramids, edges with three equivalent Se(4)Ti6 pentagonal pyramids, and  an edgeedge with one Se(5)Ti5 trigonal bipyramid. In the tenth Se site, Se(10) is bonded to one Ti(1), one Ti(2), one Ti(4), one Ti(7), one Ti(8), and one Ti(9) atom to form distorted SeTi6 pentagonal pyramids that share  a cornercorner with one Se(10)Ti6 pentagonal pyramid, corners with two equivalent Se(8)Ti6 pentagonal pyramids,  an edgeedge with one Se(4)Ti6 pentagonal pyramid,  an edgeedge with one Se(8)Ti6 pentagonal pyramid,  an edgeedge with one Se(9)Ti6 pentagonal pyramid, edges with two equivalent Se(1)Ti6 pentagonal pyramids, edges with two equivalent Se(3)Ti6 pentagonal pyramids, edges with two equivalent Se(6)Ti6 pentagonal pyramids, and edges with two equivalent Se(5)Ti5 trigonal bipyramids.
Ti19Se20 crystallizes in the triclinic P-1 space group. There are eleven inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one Se(10), one Se(2), one Se(3), one Se(5), one Se(7), and one Se(8) atom to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 42-45°. The Ti(1)-Se(10) bond length is 2.63 Å. The Ti(1)-Se(2) bond length is 2.57 Å. The Ti(1)-Se(3) bond length is 2.63 Å. The Ti(1)-Se(5) bond length is 2.61 Å. The Ti(1)-Se(7) bond length is 2.57 Å. The Ti(1)-Se(8) bond length is 2.63 Å. In the second Ti site, Ti(2) is bonded to one Se(1), one Se(10), one Se(2), one Se(4), one Se(5), and one Se(9) atom to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 42-50°. The Ti(2)-Se(1) bond length is 2.61 Å. The Ti(2)-Se(10) bond length is 2.57 Å. The Ti(2)-Se(2) bond length is 2.66 Å. The Ti(2)-Se(4) bond length is 2.58 Å. The Ti(2)-Se(5) bond length is 2.65 Å. The Ti(2)-Se(9) bond length is 2.62 Å. In the third Ti site, Ti(3) is bonded to one Se(2), one Se(6), one Se(8), one Se(9), and two equivalent Se(4) atoms to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 43-47°. The Ti(3)-Se(2) bond length is 2.57 Å. The Ti(3)-Se(6) bond length is 2.60 Å. The Ti(3)-Se(8) bond length is 2.61 Å. The Ti(3)-Se(9) bond length is 2.63 Å. There is one shorter (2.60 Å) and one longer (2.64 Å) Ti(3)-Se(4) bond length. In the fourth Ti site, Ti(4) is bonded to one Se(1), one Se(10), one Se(2), one Se(3), one Se(6), and one Se(7) atom to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 42-50°. The Ti(4)-Se(1) bond length is 2.67 Å. The Ti(4)-Se(10) bond length is 2.65 Å. The Ti(4)-Se(2) bond length is 2.60 Å. The Ti(4)-Se(3) bond length is 2.65 Å. The Ti(4)-Se(6) bond length is 2.59 Å. The Ti(4)-Se(7) bond length is 2.60 Å. In the fifth Ti site, Ti(5) is bonded to one Se(4), one Se(6), one Se(7), one Se(8), and two equivalent Se(9) atoms to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 43-48°. The Ti(5)-Se(4) bond length is 2.61 Å. The Ti(5)-Se(6) bond length is 2.60 Å. The Ti(5)-Se(7) bond length is 2.57 Å. The Ti(5)-Se(8) bond length is 2.60 Å. There is one shorter (2.63 Å) and one longer (2.65 Å) Ti(5)-Se(9) bond length. In the sixth Ti site, Ti(6) is bonded to one Se(1), one Se(3), one Se(4), one Se(5), one Se(7), and one Se(9) atom to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 42-50°. The Ti(6)-Se(1) bond length is 2.61 Å. The Ti(6)-Se(3) bond length is 2.57 Å. The Ti(6)-Se(4) bond length is 2.58 Å. The Ti(6)-Se(5) bond length is 2.65 Å. The Ti(6)-Se(7) bond length is 2.66 Å. The Ti(6)-Se(9) bond length is 2.62 Å. In the seventh Ti site, Ti(7) is bonded to one Se(10), one Se(3), one Se(4), one Se(6), and two equivalent Se(8) atoms to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 43-48°. The Ti(7)-Se(10) bond length is 2.61 Å. The Ti(7)-Se(3) bond length is 2.60 Å. The Ti(7)-Se(4) bond length is 2.58 Å. The Ti(7)-Se(6) bond length is 2.63 Å. There is one shorter (2.63 Å) and one longer (2.64 Å) Ti(7)-Se(8) bond length. In the eighth Ti site, Ti(8) is bonded to one Se(10), one Se(3), one Se(8), one Se(9), and two equivalent Se(6) atoms to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 42-47°. The Ti(8)-Se(10) bond length is 2.61 Å. The Ti(8)-Se(3) bond length is 2.60 Å. The Ti(8)-Se(8) bond length is 2.63 Å. The Ti(8)-Se(9) bond length is 2.57 Å. Both Ti(8)-Se(6) bond lengths are 2.63 Å. In the ninth Ti site, Ti(9) is bonded to two equivalent Se(1), two equivalent Se(10), and two equivalent Se(5) atoms to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 45-48°. Both Ti(9)-Se(1) bond lengths are 2.60 Å. Both Ti(9)-Se(10) bond lengths are 2.60 Å. Both Ti(9)-Se(5) bond lengths are 2.62 Å. In the tenth Ti site, Ti(10) is bonded to two equivalent Se(1), two equivalent Se(3), and two equivalent Se(5) atoms to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 46-48°. Both Ti(10)-Se(1) bond lengths are 2.60 Å. Both Ti(10)-Se(3) bond lengths are 2.59 Å. Both Ti(10)-Se(5) bond lengths are 2.62 Å. In the eleventh Ti site, Ti(11) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(7) atoms to form a mixture of face, corner, and edge-sharing TiSe6 octahedra. The corner-sharing octahedral tilt angles range from 45-46°. Both Ti(11)-Se(1) bond lengths are 2.62 Å. Both Ti(11)-Se(2) bond lengths are 2.57 Å. Both Ti(11)-Se(7) bond lengths are 2.57 Å. There are ten inequivalent Se sites. In the first Se site, Se(1) is bonded to one Ti(10), one Ti(11), one Ti(2), one Ti(4), one Ti(6), and one Ti(9) atom to form distorted SeTi6 pentagonal pyramids that share  a cornercorner with one Se(6)Ti6 pentagonal pyramid, corners with two equivalent Se(9)Ti6 pentagonal pyramids, corners with three equivalent Se(1)Ti6 pentagonal pyramids,  an edgeedge with one Se(4)Ti6 pentagonal pyramid, edges with two equivalent Se(10)Ti6 pentagonal pyramids, edges with two equivalent Se(3)Ti6 pentagonal pyramids, and edges with three equivalent Se(5)Ti5 trigonal bipyramids. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to one Ti(1), one Ti(11), one Ti(2), one Ti(3), and one Ti(4) atom. In the third Se site, Se(3) is bonded to one Ti(1), one Ti(10), one Ti(4), one Ti(6), one Ti(7), and one Ti(8) atom to form distorted SeTi6 pentagonal pyramids that share  a cornercorner with one Se(3)Ti6 pentagonal pyramid, corners with two equivalent Se(6)Ti6 pentagonal pyramids,  an edgeedge with one Se(4)Ti6 pentagonal pyramid,  an edgeedge with one Se(6)Ti6 pentagonal pyramid,  an edgeedge with one Se(9)Ti6 pentagonal pyramid, edges with two equivalent Se(1)Ti6 pentagonal pyramids, edges with two equivalent Se(10)Ti6 pentagonal pyramids, edges with two equivalent Se(8)Ti6 pentagonal pyramids, and edges with two equivalent Se(5)Ti5 trigonal bipyramids. In the fourth Se site, Se(4) is bonded to one Ti(2), one Ti(5), one Ti(6), one Ti(7), and two equivalent Ti(3) atoms to form distorted SeTi6 pentagonal pyramids that share corners with three equivalent Se(8)Ti6 pentagonal pyramids, corners with two equivalent Se(5)Ti5 trigonal bipyramids,  an edgeedge with one Se(1)Ti6 pentagonal pyramid,  an edgeedge with one Se(10)Ti6 pentagonal pyramid,  an edgeedge with one Se(3)Ti6 pentagonal pyramid,  an edgeedge with one Se(4)Ti6 pentagonal pyramid,  an edgeedge with one Se(8)Ti6 pentagonal pyramid, edges with two equivalent Se(6)Ti6 pentagonal pyramids, and edges with three equivalent Se(9)Ti6 pentagonal pyramids. In the fifth Se site, Se(5) is bonded to one Ti(1), one Ti(10), one Ti(2), one Ti(6), and one Ti(9) atom to form distorted SeTi5 trigonal bipyramids that share  a cornercorner with one Se(8)Ti6 pentagonal pyramid, corners with two equivalent Se(4)Ti6 pentagonal pyramids, corners with two equivalent Se(5)Ti5 trigonal bipyramids,  an edgeedge with one Se(9)Ti6 pentagonal pyramid, edges with two equivalent Se(10)Ti6 pentagonal pyramids, edges with two equivalent Se(3)Ti6 pentagonal pyramids, and edges with three equivalent Se(1)Ti6 pentagonal pyramids. In the sixth Se site, Se(6) is bonded to one Ti(3), one Ti(4), one Ti(5), one Ti(7), and two equivalent Ti(8) atoms to form a mixture of distorted corner and edge-sharing SeTi6 pentagonal pyramids. In the seventh Se site, Se(7) is bonded in a 5-coordinate geometry to one Ti(1), one Ti(11), one Ti(4), one Ti(5), and one Ti(6) atom. In the eighth Se site, Se(8) is bonded to one Ti(1), one Ti(3), one Ti(5), one Ti(8), and two equivalent Ti(7) atoms to form distorted SeTi6 pentagonal pyramids that share corners with two equivalent Se(10)Ti6 pentagonal pyramids, corners with three equivalent Se(4)Ti6 pentagonal pyramids,  a cornercorner with one Se(5)Ti5 trigonal bipyramid,  an edgeedge with one Se(10)Ti6 pentagonal pyramid,  an edgeedge with one Se(4)Ti6 pentagonal pyramid,  an edgeedge with one Se(8)Ti6 pentagonal pyramid, edges with two equivalent Se(3)Ti6 pentagonal pyramids, edges with two equivalent Se(9)Ti6 pentagonal pyramids, and edges with three equivalent Se(6)Ti6 pentagonal pyramids. In the ninth Se site, Se(9) is bonded to one Ti(2), one Ti(3), one Ti(6), one Ti(8), and two equivalent Ti(5) atoms to form distorted SeTi6 pentagonal pyramids that share corners with two equivalent Se(1)Ti6 pentagonal pyramids, corners with three equivalent Se(6)Ti6 pentagonal pyramids,  an edgeedge with one Se(10)Ti6 pentagonal pyramid,  an edgeedge with one Se(3)Ti6 pentagonal pyramid,  an edgeedge with one Se(6)Ti6 pentagonal pyramid,  an edgeedge with one Se(9)Ti6 pentagonal pyramid, edges with two equivalent Se(8)Ti6 pentagonal pyramids, edges with three equivalent Se(4)Ti6 pentagonal pyramids, and  an edgeedge with one Se(5)Ti5 trigonal bipyramid. In the tenth Se site, Se(10) is bonded to one Ti(1), one Ti(2), one Ti(4), one Ti(7), one Ti(8), and one Ti(9) atom to form distorted SeTi6 pentagonal pyramids that share  a cornercorner with one Se(10)Ti6 pentagonal pyramid, corners with two equivalent Se(8)Ti6 pentagonal pyramids,  an edgeedge with one Se(4)Ti6 pentagonal pyramid,  an edgeedge with one Se(8)Ti6 pentagonal pyramid,  an edgeedge with one Se(9)Ti6 pentagonal pyramid, edges with two equivalent Se(1)Ti6 pentagonal pyramids, edges with two equivalent Se(3)Ti6 pentagonal pyramids, edges with two equivalent Se(6)Ti6 pentagonal pyramids, and edges with two equivalent Se(5)Ti5 trigonal bipyramids.