Bi2B8O15 crystallizes in the triclinic P-1 space group. There are eight inequivalent B sites. In the first B site, B(1) is bonded in a tetrahedral geometry to one O(1), one O(5), one O(7), and one O(9) atom. In the second B site, B(2) is bonded in a tetrahedral geometry to one O(10), one O(2), one O(3), and one O(8) atom. In the third B site, B(3) is bonded in a trigonal planar geometry to one O(1), one O(5), and one O(6) atom. In the fourth B site, B(4) is bonded in a trigonal planar geometry to one O(2), one O(3), and one O(4) atom. In the fifth B site, B(5) is bonded in a trigonal planar geometry to one O(13), one O(15), and one O(9) atom. In the sixth B site, B(6) is bonded in a trigonal planar geometry to one O(10), one O(11), and one O(12) atom. In the seventh B site, B(7) is bonded in a trigonal planar geometry to one O(12), one O(14), and one O(15) atom. In the eighth B site, B(8) is bonded in a trigonal planar geometry to one O(11), one O(13), and one O(14) atom. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 6-coordinate geometry to one O(10), one O(2), two equivalent O(4), and two equivalent O(8) atoms. In the second Bi site, Bi(2) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(6), and two equivalent O(7) atoms. There are fifteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one B(1), one B(3), and one Bi(2) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one B(2), one B(4), and one Bi(1) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one B(2) and one B(4) atom. In the fourth O site, O(4) is bonded in a 1-coordinate geometry to one B(4) and two equivalent Bi(1) atoms. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one B(1) and one B(3) atom. In the sixth O site, O(6) is bonded in a 1-coordinate geometry to one B(3) and two equivalent Bi(2) atoms. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one B(1) and two equivalent Bi(2) atoms. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one B(2) and two equivalent Bi(1) atoms. In the ninth O site, O(9) is bonded in a bent 120 degrees geometry to one B(1) and one B(5) atom. In the tenth O site, O(10) is bonded in a distorted bent 120 degrees geometry to one B(2), one B(6), and one Bi(1) atom. In the eleventh O site, O(11) is bonded in a bent 120 degrees geometry to one B(6) and one B(8) atom. In the twelfth O site, O(12) is bonded in a bent 120 degrees geometry to one B(6) and one B(7) atom. In the thirteenth O site, O(13) is bonded in a bent 120 degrees geometry to one B(5) and one B(8) atom. In the fourteenth O site, O(14) is bonded in a bent 120 degrees geometry to one B(7) and one B(8) atom. In the fifteenth O site, O(15) is bonded in a bent 120 degrees geometry to one B(5) and one B(7) atom.
Bi2B8O15 crystallizes in the triclinic P-1 space group. There are eight inequivalent B sites. In the first B site, B(1) is bonded in a tetrahedral geometry to one O(1), one O(5), one O(7), and one O(9) atom. The B(1)-O(1) bond length is 1.47 Å. The B(1)-O(5) bond length is 1.44 Å. The B(1)-O(7) bond length is 1.46 Å. The B(1)-O(9) bond length is 1.51 Å. In the second B site, B(2) is bonded in a tetrahedral geometry to one O(10), one O(2), one O(3), and one O(8) atom. The B(2)-O(10) bond length is 1.50 Å. The B(2)-O(2) bond length is 1.47 Å. The B(2)-O(3) bond length is 1.44 Å. The B(2)-O(8) bond length is 1.46 Å. In the third B site, B(3) is bonded in a trigonal planar geometry to one O(1), one O(5), and one O(6) atom. The B(3)-O(1) bond length is 1.39 Å. The B(3)-O(5) bond length is 1.35 Å. The B(3)-O(6) bond length is 1.36 Å. In the fourth B site, B(4) is bonded in a trigonal planar geometry to one O(2), one O(3), and one O(4) atom. The B(4)-O(2) bond length is 1.39 Å. The B(4)-O(3) bond length is 1.36 Å. The B(4)-O(4) bond length is 1.35 Å. In the fifth B site, B(5) is bonded in a trigonal planar geometry to one O(13), one O(15), and one O(9) atom. The B(5)-O(13) bond length is 1.38 Å. The B(5)-O(15) bond length is 1.37 Å. The B(5)-O(9) bond length is 1.34 Å. In the sixth B site, B(6) is bonded in a trigonal planar geometry to one O(10), one O(11), and one O(12) atom. The B(6)-O(10) bond length is 1.33 Å. The B(6)-O(11) bond length is 1.38 Å. The B(6)-O(12) bond length is 1.39 Å. In the seventh B site, B(7) is bonded in a trigonal planar geometry to one O(12), one O(14), and one O(15) atom. The B(7)-O(12) bond length is 1.37 Å. The B(7)-O(14) bond length is 1.38 Å. The B(7)-O(15) bond length is 1.34 Å. In the eighth B site, B(8) is bonded in a trigonal planar geometry to one O(11), one O(13), and one O(14) atom. The B(8)-O(11) bond length is 1.37 Å. The B(8)-O(13) bond length is 1.35 Å. The B(8)-O(14) bond length is 1.38 Å. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 6-coordinate geometry to one O(10), one O(2), two equivalent O(4), and two equivalent O(8) atoms. The Bi(1)-O(10) bond length is 2.74 Å. The Bi(1)-O(2) bond length is 2.50 Å. There is one shorter (2.15 Å) and one longer (2.63 Å) Bi(1)-O(4) bond length. There is one shorter (2.15 Å) and one longer (2.30 Å) Bi(1)-O(8) bond length. In the second Bi site, Bi(2) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(6), and two equivalent O(7) atoms. The Bi(2)-O(1) bond length is 2.49 Å. There is one shorter (2.15 Å) and one longer (2.62 Å) Bi(2)-O(6) bond length. There is one shorter (2.16 Å) and one longer (2.29 Å) Bi(2)-O(7) bond length. There are fifteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one B(1), one B(3), and one Bi(2) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one B(2), one B(4), and one Bi(1) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one B(2) and one B(4) atom. In the fourth O site, O(4) is bonded in a 1-coordinate geometry to one B(4) and two equivalent Bi(1) atoms. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one B(1) and one B(3) atom. In the sixth O site, O(6) is bonded in a 1-coordinate geometry to one B(3) and two equivalent Bi(2) atoms. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one B(1) and two equivalent Bi(2) atoms. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one B(2) and two equivalent Bi(1) atoms. In the ninth O site, O(9) is bonded in a bent 120 degrees geometry to one B(1) and one B(5) atom. In the tenth O site, O(10) is bonded in a distorted bent 120 degrees geometry to one B(2), one B(6), and one Bi(1) atom. In the eleventh O site, O(11) is bonded in a bent 120 degrees geometry to one B(6) and one B(8) atom. In the twelfth O site, O(12) is bonded in a bent 120 degrees geometry to one B(6) and one B(7) atom. In the thirteenth O site, O(13) is bonded in a bent 120 degrees geometry to one B(5) and one B(8) atom. In the fourteenth O site, O(14) is bonded in a bent 120 degrees geometry to one B(7) and one B(8) atom. In the fifteenth O site, O(15) is bonded in a bent 120 degrees geometry to one B(5) and one B(7) atom.