V3CuO8 crystallizes in the monoclinic Cm space group. There are three inequivalent V sites. In the first V site, V(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(4), one O(5), and two equivalent O(8) atoms. In the second V site, V(2) is bonded in a 6-coordinate geometry to one O(4), one O(5), one O(6), one O(7), and two equivalent O(1) atoms. In the third V site, V(3) is bonded to one O(1), one O(2), one O(3), one O(4), and two equivalent O(7) atoms to form corner-sharing VO6 octahedra. The corner-sharing octahedral tilt angles are 27°. Cu(1) is bonded in a 6-coordinate geometry to one O(5), one O(6), one O(7), one O(8), and two equivalent O(2) atoms. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one V(3) and two equivalent V(2) atoms. In the second O site, O(2) is bonded to one V(1), one V(3), and two equivalent Cu(1) atoms to form OV2Cu2 tetrahedra that share corners with two equivalent O(2)V2Cu2 tetrahedra and edges with two equivalent O(7)V3Cu trigonal pyramids. In the third O site, O(3) is bonded in a linear geometry to one V(1) and one V(3) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one V(1), one V(2), and one V(3) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one V(1), one V(2), and one Cu(1) atom. In the sixth O site, O(6) is bonded in a distorted linear geometry to one V(2) and one Cu(1) atom. In the seventh O site, O(7) is bonded to one V(2), two equivalent V(3), and one Cu(1) atom to form distorted OV3Cu trigonal pyramids that share corners with two equivalent O(7)V3Cu trigonal pyramids and edges with two equivalent O(2)V2Cu2 tetrahedra. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to two equivalent V(1) and one Cu(1) atom.
V3CuO8 crystallizes in the monoclinic Cm space group. There are three inequivalent V sites. In the first V site, V(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(4), one O(5), and two equivalent O(8) atoms. The V(1)-O(2) bond length is 2.10 Å. The V(1)-O(3) bond length is 1.71 Å. The V(1)-O(4) bond length is 2.54 Å. The V(1)-O(5) bond length is 1.72 Å. Both V(1)-O(8) bond lengths are 1.94 Å. In the second V site, V(2) is bonded in a 6-coordinate geometry to one O(4), one O(5), one O(6), one O(7), and two equivalent O(1) atoms. The V(2)-O(4) bond length is 1.84 Å. The V(2)-O(5) bond length is 2.42 Å. The V(2)-O(6) bond length is 1.63 Å. The V(2)-O(7) bond length is 1.96 Å. Both V(2)-O(1) bond lengths are 1.93 Å. In the third V site, V(3) is bonded to one O(1), one O(2), one O(3), one O(4), and two equivalent O(7) atoms to form corner-sharing VO6 octahedra. The corner-sharing octahedral tilt angles are 27°. The V(3)-O(1) bond length is 2.02 Å. The V(3)-O(2) bond length is 2.06 Å. The V(3)-O(3) bond length is 1.98 Å. The V(3)-O(4) bond length is 1.79 Å. Both V(3)-O(7) bond lengths are 1.93 Å. Cu(1) is bonded in a 6-coordinate geometry to one O(5), one O(6), one O(7), one O(8), and two equivalent O(2) atoms. The Cu(1)-O(5) bond length is 1.98 Å. The Cu(1)-O(6) bond length is 2.07 Å. The Cu(1)-O(7) bond length is 2.52 Å. The Cu(1)-O(8) bond length is 1.97 Å. Both Cu(1)-O(2) bond lengths are 1.97 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one V(3) and two equivalent V(2) atoms. In the second O site, O(2) is bonded to one V(1), one V(3), and two equivalent Cu(1) atoms to form OV2Cu2 tetrahedra that share corners with two equivalent O(2)V2Cu2 tetrahedra and edges with two equivalent O(7)V3Cu trigonal pyramids. In the third O site, O(3) is bonded in a linear geometry to one V(1) and one V(3) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one V(1), one V(2), and one V(3) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one V(1), one V(2), and one Cu(1) atom. In the sixth O site, O(6) is bonded in a distorted linear geometry to one V(2) and one Cu(1) atom. In the seventh O site, O(7) is bonded to one V(2), two equivalent V(3), and one Cu(1) atom to form distorted OV3Cu trigonal pyramids that share corners with two equivalent O(7)V3Cu trigonal pyramids and edges with two equivalent O(2)V2Cu2 tetrahedra. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to two equivalent V(1) and one Cu(1) atom.