K3CuO2 crystallizes in the tetragonal P4_12_12 space group. There are four inequivalent K sites. In the first K site, K(1) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(2) atoms. In the second K site, K(2) is bonded in a 5-coordinate geometry to one Cu(1), two equivalent O(1), and two equivalent O(2) atoms. In the third K site, K(3) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(2) atoms. In the fourth K site, K(4) is bonded in a distorted tetrahedral geometry to two equivalent O(1) and two equivalent O(2) atoms. Cu(1) is bonded in a linear geometry to one K(2), one O(1), and one O(2) atom. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 7-coordinate geometry to one K(3), one K(4), two equivalent K(1), two equivalent K(2), and one Cu(1) atom. In the second O site, O(2) is bonded in a 7-coordinate geometry to one K(3), one K(4), two equivalent K(1), two equivalent K(2), and one Cu(1) atom.
K3CuO2 crystallizes in the tetragonal P4_12_12 space group. There are four inequivalent K sites. In the first K site, K(1) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(2) atoms. There is one shorter (2.79 Å) and one longer (2.80 Å) K(1)-O(1) bond length. There is one shorter (2.75 Å) and one longer (2.82 Å) K(1)-O(2) bond length. In the second K site, K(2) is bonded in a 5-coordinate geometry to one Cu(1), two equivalent O(1), and two equivalent O(2) atoms. The K(2)-Cu(1) bond length is 3.16 Å. There is one shorter (2.62 Å) and one longer (2.91 Å) K(2)-O(1) bond length. There is one shorter (2.63 Å) and one longer (3.03 Å) K(2)-O(2) bond length. In the third K site, K(3) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(2) atoms. Both K(3)-O(1) bond lengths are 2.77 Å. Both K(3)-O(2) bond lengths are 2.88 Å. In the fourth K site, K(4) is bonded in a distorted tetrahedral geometry to two equivalent O(1) and two equivalent O(2) atoms. Both K(4)-O(1) bond lengths are 2.85 Å. Both K(4)-O(2) bond lengths are 2.73 Å. Cu(1) is bonded in a linear geometry to one K(2), one O(1), and one O(2) atom. The Cu(1)-O(1) bond length is 1.80 Å. The Cu(1)-O(2) bond length is 1.80 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 7-coordinate geometry to one K(3), one K(4), two equivalent K(1), two equivalent K(2), and one Cu(1) atom. In the second O site, O(2) is bonded in a 7-coordinate geometry to one K(3), one K(4), two equivalent K(1), two equivalent K(2), and one Cu(1) atom.