RbCuSe4 crystallizes in the orthorhombic P2_12_12_1 space group. Rb(1) is bonded in a 14-coordinate geometry to three equivalent Cu(1), two equivalent Se(4), three equivalent Se(1), three equivalent Se(2), and three equivalent Se(3) atoms. Cu(1) is bonded to three equivalent Rb(1), one Se(1), one Se(3), and two equivalent Se(2) atoms to form a mixture of distorted corner and edge-sharing CuRb3Se4 tetrahedra. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted single-bond geometry to three equivalent Rb(1), one Cu(1), and one Se(4) atom. In the second Se site, Se(2) is bonded in a distorted water-like geometry to three equivalent Rb(1) and two equivalent Cu(1) atoms. In the third Se site, Se(3) is bonded in a 1-coordinate geometry to three equivalent Rb(1), one Cu(1), and one Se(4) atom. In the fourth Se site, Se(4) is bonded in a 4-coordinate geometry to two equivalent Rb(1), one Se(1), and one Se(3) atom.
RbCuSe4 crystallizes in the orthorhombic P2_12_12_1 space group. Rb(1) is bonded in a 14-coordinate geometry to three equivalent Cu(1), two equivalent Se(4), three equivalent Se(1), three equivalent Se(2), and three equivalent Se(3) atoms. There are a spread of Rb(1)-Cu(1) bond distances ranging from 3.79-4.15 Å. There is one shorter (3.48 Å) and one longer (3.66 Å) Rb(1)-Se(4) bond length. There are a spread of Rb(1)-Se(1) bond distances ranging from 3.55-3.70 Å. There are a spread of Rb(1)-Se(2) bond distances ranging from 3.52-4.02 Å. There are a spread of Rb(1)-Se(3) bond distances ranging from 3.58-3.89 Å. Cu(1) is bonded to three equivalent Rb(1), one Se(1), one Se(3), and two equivalent Se(2) atoms to form a mixture of distorted corner and edge-sharing CuRb3Se4 tetrahedra. The Cu(1)-Se(1) bond length is 2.41 Å. The Cu(1)-Se(3) bond length is 2.46 Å. There is one shorter (2.40 Å) and one longer (2.44 Å) Cu(1)-Se(2) bond length. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted single-bond geometry to three equivalent Rb(1), one Cu(1), and one Se(4) atom. The Se(1)-Se(4) bond length is 2.37 Å. In the second Se site, Se(2) is bonded in a distorted water-like geometry to three equivalent Rb(1) and two equivalent Cu(1) atoms. In the third Se site, Se(3) is bonded in a 1-coordinate geometry to three equivalent Rb(1), one Cu(1), and one Se(4) atom. The Se(3)-Se(4) bond length is 2.41 Å. In the fourth Se site, Se(4) is bonded in a 4-coordinate geometry to two equivalent Rb(1), one Se(1), and one Se(3) atom.