CuSeO3 crystallizes in the triclinic P-1 space group. There are four inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(1), one O(2), one O(4), one O(6), and one O(8) atom to form corner-sharing CuO5 trigonal bipyramids. In the second Cu site, Cu(2) is bonded to one O(3), one O(6), one O(7), and two equivalent O(9) atoms to form a mixture of distorted corner and edge-sharing CuO5 trigonal bipyramids. In the third Cu site, Cu(3) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(8) atoms. In the fourth Cu site, Cu(4) is bonded in a square co-planar geometry to two equivalent O(2) and two equivalent O(5) atoms. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a trigonal non-coplanar geometry to one O(3), one O(7), and one O(8) atom. In the second Se site, Se(2) is bonded in a distorted trigonal non-coplanar geometry to one O(2), one O(6), and one O(9) atom. In the third Se site, Se(3) is bonded in a trigonal non-coplanar geometry to one O(1), one O(4), and one O(5) atom. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Cu(1), one Cu(3), and one Se(3) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Cu(1), one Cu(4), and one Se(2) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Cu(2) and one Se(1) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Cu(1) and one Se(3) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Cu(4) and one Se(3) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Cu(1), one Cu(2), and one Se(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Cu(2) and one Se(1) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Cu(1), one Cu(3), and one Se(1) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to two equivalent Cu(2) and one Se(2) atom.
CuSeO3 crystallizes in the triclinic P-1 space group. There are four inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(1), one O(2), one O(4), one O(6), and one O(8) atom to form corner-sharing CuO5 trigonal bipyramids. The Cu(1)-O(1) bond length is 2.00 Å. The Cu(1)-O(2) bond length is 2.00 Å. The Cu(1)-O(4) bond length is 1.91 Å. The Cu(1)-O(6) bond length is 1.98 Å. The Cu(1)-O(8) bond length is 2.17 Å. In the second Cu site, Cu(2) is bonded to one O(3), one O(6), one O(7), and two equivalent O(9) atoms to form a mixture of distorted corner and edge-sharing CuO5 trigonal bipyramids. The Cu(2)-O(3) bond length is 1.94 Å. The Cu(2)-O(6) bond length is 1.97 Å. The Cu(2)-O(7) bond length is 1.97 Å. There is one shorter (1.99 Å) and one longer (2.28 Å) Cu(2)-O(9) bond length. In the third Cu site, Cu(3) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(8) atoms. Both Cu(3)-O(1) bond lengths are 1.99 Å. Both Cu(3)-O(8) bond lengths are 1.95 Å. In the fourth Cu site, Cu(4) is bonded in a square co-planar geometry to two equivalent O(2) and two equivalent O(5) atoms. Both Cu(4)-O(2) bond lengths are 1.91 Å. Both Cu(4)-O(5) bond lengths are 1.92 Å. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a trigonal non-coplanar geometry to one O(3), one O(7), and one O(8) atom. The Se(1)-O(3) bond length is 1.70 Å. The Se(1)-O(7) bond length is 1.71 Å. The Se(1)-O(8) bond length is 1.75 Å. In the second Se site, Se(2) is bonded in a distorted trigonal non-coplanar geometry to one O(2), one O(6), and one O(9) atom. The Se(2)-O(2) bond length is 1.76 Å. The Se(2)-O(6) bond length is 1.77 Å. The Se(2)-O(9) bond length is 1.68 Å. In the third Se site, Se(3) is bonded in a trigonal non-coplanar geometry to one O(1), one O(4), and one O(5) atom. The Se(3)-O(1) bond length is 1.76 Å. The Se(3)-O(4) bond length is 1.69 Å. The Se(3)-O(5) bond length is 1.70 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Cu(1), one Cu(3), and one Se(3) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Cu(1), one Cu(4), and one Se(2) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Cu(2) and one Se(1) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Cu(1) and one Se(3) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Cu(4) and one Se(3) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Cu(1), one Cu(2), and one Se(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Cu(2) and one Se(1) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Cu(1), one Cu(3), and one Se(1) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to two equivalent Cu(2) and one Se(2) atom.