Cs3B3Se10 crystallizes in the triclinic P-1 space group. There are three inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 10-coordinate geometry to one Se(10), one Se(3), one Se(7), two equivalent Se(5), two equivalent Se(8), and three equivalent Se(9) atoms. In the second Cs site, Cs(2) is bonded in a 10-coordinate geometry to one Se(1), one Se(10), one Se(3), one Se(5), one Se(6), one Se(7), two equivalent Se(2), and two equivalent Se(4) atoms. In the third Cs site, Cs(3) is bonded in a 11-coordinate geometry to one Se(10), one Se(2), one Se(4), one Se(5), one Se(6), one Se(7), one Se(9), two equivalent Se(1), and two equivalent Se(3) atoms. There are three inequivalent B sites. In the first B site, B(1) is bonded to one Se(1), one Se(2), one Se(3), and one Se(4) atom to form corner-sharing BSe4 tetrahedra. In the second B site, B(2) is bonded to one Se(4), one Se(5), one Se(6), and one Se(7) atom to form corner-sharing BSe4 tetrahedra. In the third B site, B(3) is bonded to one Se(10), one Se(7), one Se(8), and one Se(9) atom to form corner-sharing BSe4 tetrahedra. There are ten inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted single-bond geometry to one Cs(2), two equivalent Cs(3), and one B(1) atom. In the second Se site, Se(2) is bonded in a distorted single-bond geometry to one Cs(3), two equivalent Cs(2), and one B(1) atom. In the third Se site, Se(3) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), two equivalent Cs(3), and one B(1) atom. In the fourth Se site, Se(4) is bonded in a distorted water-like geometry to one Cs(3), two equivalent Cs(2), one B(1), and one B(2) atom. In the fifth Se site, Se(5) is bonded in a distorted single-bond geometry to one Cs(2), one Cs(3), two equivalent Cs(1), and one B(2) atom. In the sixth Se site, Se(6) is bonded in a distorted single-bond geometry to one Cs(2), one Cs(3), and one B(2) atom. In the seventh Se site, Se(7) is bonded in a distorted water-like geometry to one Cs(1), one Cs(2), one Cs(3), one B(2), and one B(3) atom. In the eighth Se site, Se(8) is bonded in a distorted single-bond geometry to two equivalent Cs(1) and one B(3) atom. In the ninth Se site, Se(9) is bonded in a distorted single-bond geometry to one Cs(3), three equivalent Cs(1), and one B(3) atom. In the tenth Se site, Se(10) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), one Cs(3), and one B(3) atom.
Cs3B3Se10 crystallizes in the triclinic P-1 space group. There are three inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 10-coordinate geometry to one Se(10), one Se(3), one Se(7), two equivalent Se(5), two equivalent Se(8), and three equivalent Se(9) atoms. The Cs(1)-Se(10) bond length is 4.02 Å. The Cs(1)-Se(3) bond length is 4.16 Å. The Cs(1)-Se(7) bond length is 3.97 Å. There is one shorter (3.94 Å) and one longer (4.05 Å) Cs(1)-Se(5) bond length. There is one shorter (3.67 Å) and one longer (3.82 Å) Cs(1)-Se(8) bond length. There are a spread of Cs(1)-Se(9) bond distances ranging from 3.99-4.03 Å. In the second Cs site, Cs(2) is bonded in a 10-coordinate geometry to one Se(1), one Se(10), one Se(3), one Se(5), one Se(6), one Se(7), two equivalent Se(2), and two equivalent Se(4) atoms. The Cs(2)-Se(1) bond length is 4.19 Å. The Cs(2)-Se(10) bond length is 3.90 Å. The Cs(2)-Se(3) bond length is 4.32 Å. The Cs(2)-Se(5) bond length is 4.17 Å. The Cs(2)-Se(6) bond length is 3.76 Å. The Cs(2)-Se(7) bond length is 3.86 Å. There is one shorter (3.65 Å) and one longer (4.14 Å) Cs(2)-Se(2) bond length. There is one shorter (3.84 Å) and one longer (3.85 Å) Cs(2)-Se(4) bond length. In the third Cs site, Cs(3) is bonded in a 11-coordinate geometry to one Se(10), one Se(2), one Se(4), one Se(5), one Se(6), one Se(7), one Se(9), two equivalent Se(1), and two equivalent Se(3) atoms. The Cs(3)-Se(10) bond length is 3.87 Å. The Cs(3)-Se(2) bond length is 4.10 Å. The Cs(3)-Se(4) bond length is 4.05 Å. The Cs(3)-Se(5) bond length is 3.89 Å. The Cs(3)-Se(6) bond length is 3.86 Å. The Cs(3)-Se(7) bond length is 3.88 Å. The Cs(3)-Se(9) bond length is 3.91 Å. There is one shorter (3.72 Å) and one longer (3.90 Å) Cs(3)-Se(1) bond length. There is one shorter (3.91 Å) and one longer (3.97 Å) Cs(3)-Se(3) bond length. There are three inequivalent B sites. In the first B site, B(1) is bonded to one Se(1), one Se(2), one Se(3), and one Se(4) atom to form corner-sharing BSe4 tetrahedra. The B(1)-Se(1) bond length is 2.06 Å. The B(1)-Se(2) bond length is 2.05 Å. The B(1)-Se(3) bond length is 2.07 Å. The B(1)-Se(4) bond length is 2.08 Å. In the second B site, B(2) is bonded to one Se(4), one Se(5), one Se(6), and one Se(7) atom to form corner-sharing BSe4 tetrahedra. The B(2)-Se(4) bond length is 2.07 Å. The B(2)-Se(5) bond length is 2.08 Å. The B(2)-Se(6) bond length is 2.05 Å. The B(2)-Se(7) bond length is 2.11 Å. In the third B site, B(3) is bonded to one Se(10), one Se(7), one Se(8), and one Se(9) atom to form corner-sharing BSe4 tetrahedra. The B(3)-Se(10) bond length is 2.06 Å. The B(3)-Se(7) bond length is 2.07 Å. The B(3)-Se(8) bond length is 2.06 Å. The B(3)-Se(9) bond length is 2.06 Å. There are ten inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted single-bond geometry to one Cs(2), two equivalent Cs(3), and one B(1) atom. In the second Se site, Se(2) is bonded in a distorted single-bond geometry to one Cs(3), two equivalent Cs(2), and one B(1) atom. In the third Se site, Se(3) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), two equivalent Cs(3), and one B(1) atom. In the fourth Se site, Se(4) is bonded in a distorted water-like geometry to one Cs(3), two equivalent Cs(2), one B(1), and one B(2) atom. In the fifth Se site, Se(5) is bonded in a distorted single-bond geometry to one Cs(2), one Cs(3), two equivalent Cs(1), and one B(2) atom. In the sixth Se site, Se(6) is bonded in a distorted single-bond geometry to one Cs(2), one Cs(3), and one B(2) atom. In the seventh Se site, Se(7) is bonded in a distorted water-like geometry to one Cs(1), one Cs(2), one Cs(3), one B(2), and one B(3) atom. In the eighth Se site, Se(8) is bonded in a distorted single-bond geometry to two equivalent Cs(1) and one B(3) atom. In the ninth Se site, Se(9) is bonded in a distorted single-bond geometry to one Cs(3), three equivalent Cs(1), and one B(3) atom. In the tenth Se site, Se(10) is bonded in a distorted single-bond geometry to one Cs(1), one Cs(2), one Cs(3), and one B(3) atom.