Cu9Se8 is Aluminum carbonitride-derived structured and crystallizes in the triclinic P1 space group. There are nine inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one Se(2) and three equivalent Se(1) atoms to form distorted corner-sharing CuSe4 tetrahedra. In the second Cu site, Cu(2) is bonded in a 4-coordinate geometry to one Se(3) and three equivalent Se(2) atoms. In the third Cu site, Cu(3) is bonded in a 4-coordinate geometry to one Se(2) and three equivalent Se(3) atoms. In the fourth Cu site, Cu(4) is bonded to one Se(3) and three equivalent Se(5) atoms to form corner-sharing CuSe4 tetrahedra. In the fifth Cu site, Cu(5) is bonded to one Se(5) and three equivalent Se(4) atoms to form corner-sharing CuSe4 tetrahedra. In the sixth Cu site, Cu(6) is bonded to one Se(4) and three equivalent Se(6) atoms to form corner-sharing CuSe4 tetrahedra. In the seventh Cu site, Cu(7) is bonded to one Se(6) and three equivalent Se(7) atoms to form corner-sharing CuSe4 tetrahedra. In the eighth Cu site, Cu(8) is bonded to one Se(7) and three equivalent Se(8) atoms to form corner-sharing CuSe4 tetrahedra. In the ninth Cu site, Cu(9) is bonded in a 4-coordinate geometry to one Se(8) and three equivalent Se(1) atoms. There are eight inequivalent Se sites. In the first Se site, Se(1) is bonded to three equivalent Cu(1) and three equivalent Cu(9) atoms to form distorted SeCu6 octahedra that share corners with three equivalent Se(8)Cu4 tetrahedra and edges with six equivalent Se(1)Cu6 octahedra. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to one Cu(1), one Cu(3), and three equivalent Cu(2) atoms. In the third Se site, Se(3) is bonded in a 5-coordinate geometry to one Cu(2), one Cu(4), and three equivalent Cu(3) atoms. In the fourth Se site, Se(4) is bonded to one Cu(6) and three equivalent Cu(5) atoms to form corner-sharing SeCu4 tetrahedra. In the fifth Se site, Se(5) is bonded to one Cu(5) and three equivalent Cu(4) atoms to form corner-sharing SeCu4 tetrahedra. In the sixth Se site, Se(6) is bonded to one Cu(7) and three equivalent Cu(6) atoms to form corner-sharing SeCu4 tetrahedra. In the seventh Se site, Se(7) is bonded to one Cu(8) and three equivalent Cu(7) atoms to form corner-sharing SeCu4 tetrahedra. In the eighth Se site, Se(8) is bonded to one Cu(9) and three equivalent Cu(8) atoms to form SeCu4 tetrahedra that share corners with three equivalent Se(1)Cu6 octahedra, corners with three equivalent Se(7)Cu4 tetrahedra, and corners with six equivalent Se(8)Cu4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-78°.
Cu9Se8 is Aluminum carbonitride-derived structured and crystallizes in the triclinic P1 space group. There are nine inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one Se(2) and three equivalent Se(1) atoms to form distorted corner-sharing CuSe4 tetrahedra. The Cu(1)-Se(2) bond length is 2.49 Å. There are a spread of Cu(1)-Se(1) bond distances ranging from 2.19-2.68 Å. In the second Cu site, Cu(2) is bonded in a 4-coordinate geometry to one Se(3) and three equivalent Se(2) atoms. The Cu(2)-Se(3) bond length is 2.61 Å. There are a spread of Cu(2)-Se(2) bond distances ranging from 2.19-2.61 Å. In the third Cu site, Cu(3) is bonded in a 4-coordinate geometry to one Se(2) and three equivalent Se(3) atoms. The Cu(3)-Se(2) bond length is 2.59 Å. There are a spread of Cu(3)-Se(3) bond distances ranging from 2.19-2.62 Å. In the fourth Cu site, Cu(4) is bonded to one Se(3) and three equivalent Se(5) atoms to form corner-sharing CuSe4 tetrahedra. The Cu(4)-Se(3) bond length is 2.54 Å. There are a spread of Cu(4)-Se(5) bond distances ranging from 2.19-2.58 Å. In the fifth Cu site, Cu(5) is bonded to one Se(5) and three equivalent Se(4) atoms to form corner-sharing CuSe4 tetrahedra. The Cu(5)-Se(5) bond length is 2.50 Å. There are a spread of Cu(5)-Se(4) bond distances ranging from 2.20-2.62 Å. In the sixth Cu site, Cu(6) is bonded to one Se(4) and three equivalent Se(6) atoms to form corner-sharing CuSe4 tetrahedra. The Cu(6)-Se(4) bond length is 2.51 Å. There are a spread of Cu(6)-Se(6) bond distances ranging from 2.20-2.62 Å. In the seventh Cu site, Cu(7) is bonded to one Se(6) and three equivalent Se(7) atoms to form corner-sharing CuSe4 tetrahedra. The Cu(7)-Se(6) bond length is 2.51 Å. There are a spread of Cu(7)-Se(7) bond distances ranging from 2.20-2.60 Å. In the eighth Cu site, Cu(8) is bonded to one Se(7) and three equivalent Se(8) atoms to form corner-sharing CuSe4 tetrahedra. The Cu(8)-Se(7) bond length is 2.50 Å. There are a spread of Cu(8)-Se(8) bond distances ranging from 2.19-2.58 Å. In the ninth Cu site, Cu(9) is bonded in a 4-coordinate geometry to one Se(8) and three equivalent Se(1) atoms. The Cu(9)-Se(8) bond length is 2.45 Å. There are a spread of Cu(9)-Se(1) bond distances ranging from 2.21-2.72 Å. There are eight inequivalent Se sites. In the first Se site, Se(1) is bonded to three equivalent Cu(1) and three equivalent Cu(9) atoms to form distorted SeCu6 octahedra that share corners with three equivalent Se(8)Cu4 tetrahedra and edges with six equivalent Se(1)Cu6 octahedra. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to one Cu(1), one Cu(3), and three equivalent Cu(2) atoms. In the third Se site, Se(3) is bonded in a 5-coordinate geometry to one Cu(2), one Cu(4), and three equivalent Cu(3) atoms. In the fourth Se site, Se(4) is bonded to one Cu(6) and three equivalent Cu(5) atoms to form corner-sharing SeCu4 tetrahedra. In the fifth Se site, Se(5) is bonded to one Cu(5) and three equivalent Cu(4) atoms to form corner-sharing SeCu4 tetrahedra. In the sixth Se site, Se(6) is bonded to one Cu(7) and three equivalent Cu(6) atoms to form corner-sharing SeCu4 tetrahedra. In the seventh Se site, Se(7) is bonded to one Cu(8) and three equivalent Cu(7) atoms to form corner-sharing SeCu4 tetrahedra. In the eighth Se site, Se(8) is bonded to one Cu(9) and three equivalent Cu(8) atoms to form SeCu4 tetrahedra that share corners with three equivalent Se(1)Cu6 octahedra, corners with three equivalent Se(7)Cu4 tetrahedra, and corners with six equivalent Se(8)Cu4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-78°.