Cs4K2Cu(SiO4)2 crystallizes in the tetragonal P4_2/mnm space group. Cs(1) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(2) atoms. K(1) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(1) atoms. Cu(1) is bonded in a square co-planar geometry to four equivalent O(1) atoms. Si(1) is bonded in a tetrahedral geometry to two equivalent O(1) and two equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to two equivalent Cs(1), two equivalent K(1), one Cu(1), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to four equivalent Cs(1), one K(1), and one Si(1) atom.
Cs4K2Cu(SiO4)2 crystallizes in the tetragonal P4_2/mnm space group. Cs(1) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(2) atoms. Both Cs(1)-O(1) bond lengths are 3.30 Å. There are a spread of Cs(1)-O(2) bond distances ranging from 3.05-3.13 Å. K(1) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(1) atoms. Both K(1)-O(2) bond lengths are 2.73 Å. All K(1)-O(1) bond lengths are 2.83 Å. Cu(1) is bonded in a square co-planar geometry to four equivalent O(1) atoms. All Cu(1)-O(1) bond lengths are 2.00 Å. Si(1) is bonded in a tetrahedral geometry to two equivalent O(1) and two equivalent O(2) atoms. Both Si(1)-O(1) bond lengths are 1.69 Å. Both Si(1)-O(2) bond lengths are 1.65 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to two equivalent Cs(1), two equivalent K(1), one Cu(1), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to four equivalent Cs(1), one K(1), and one Si(1) atom.