KHoCoSi2O7 crystallizes in the monoclinic C2 space group. K(1) is bonded in a 8-coordinate geometry to one O(3), one O(4), one O(5), one O(6), one O(7), one O(8), and two equivalent O(1) atoms. Ho(1) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), and two equivalent O(7) atoms. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent O(3) and two equivalent O(5) atoms to form CoO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. In the second Co site, Co(2) is bonded to two equivalent O(4) and two equivalent O(6) atoms to form distorted CoO4 trigonal pyramids that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Co(1)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Co(2)O4 trigonal pyramid. In the second Si site, Si(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Co(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Co(2)O4 trigonal pyramid. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent K(1), one Ho(1), and one Si(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to two equivalent Ho(1) and two equivalent Si(1) atoms. In the third O site, O(3) is bonded in a 4-coordinate geometry to one K(1), one Ho(1), one Co(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one K(1), one Ho(1), one Co(2), and one Si(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one K(1), one Ho(1), one Co(1), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one K(1), one Ho(1), one Co(2), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one K(1), two equivalent Ho(1), and one Si(2) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to two equivalent K(1) and two equivalent Si(2) atoms.
KHoCoSi2O7 crystallizes in the monoclinic C2 space group. K(1) is bonded in a 8-coordinate geometry to one O(3), one O(4), one O(5), one O(6), one O(7), one O(8), and two equivalent O(1) atoms. The K(1)-O(3) bond length is 2.68 Å. The K(1)-O(4) bond length is 2.89 Å. The K(1)-O(5) bond length is 2.90 Å. The K(1)-O(6) bond length is 2.84 Å. The K(1)-O(7) bond length is 2.76 Å. The K(1)-O(8) bond length is 2.78 Å. There is one shorter (2.80 Å) and one longer (2.98 Å) K(1)-O(1) bond length. Ho(1) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), and two equivalent O(7) atoms. The Ho(1)-O(1) bond length is 2.17 Å. The Ho(1)-O(2) bond length is 3.03 Å. The Ho(1)-O(3) bond length is 2.67 Å. The Ho(1)-O(4) bond length is 2.57 Å. The Ho(1)-O(5) bond length is 2.40 Å. The Ho(1)-O(6) bond length is 2.28 Å. There is one shorter (2.63 Å) and one longer (2.71 Å) Ho(1)-O(7) bond length. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent O(3) and two equivalent O(5) atoms to form CoO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. Both Co(1)-O(3) bond lengths are 1.98 Å. Both Co(1)-O(5) bond lengths are 1.96 Å. In the second Co site, Co(2) is bonded to two equivalent O(4) and two equivalent O(6) atoms to form distorted CoO4 trigonal pyramids that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. Both Co(2)-O(4) bond lengths are 1.97 Å. Both Co(2)-O(6) bond lengths are 1.99 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Co(1)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Co(2)O4 trigonal pyramid. The Si(1)-O(1) bond length is 1.63 Å. The Si(1)-O(2) bond length is 1.64 Å. The Si(1)-O(3) bond length is 1.64 Å. The Si(1)-O(4) bond length is 1.65 Å. In the second Si site, Si(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Co(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Co(2)O4 trigonal pyramid. The Si(2)-O(5) bond length is 1.65 Å. The Si(2)-O(6) bond length is 1.66 Å. The Si(2)-O(7) bond length is 1.63 Å. The Si(2)-O(8) bond length is 1.66 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent K(1), one Ho(1), and one Si(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to two equivalent Ho(1) and two equivalent Si(1) atoms. In the third O site, O(3) is bonded in a 4-coordinate geometry to one K(1), one Ho(1), one Co(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one K(1), one Ho(1), one Co(2), and one Si(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one K(1), one Ho(1), one Co(1), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one K(1), one Ho(1), one Co(2), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one K(1), two equivalent Ho(1), and one Si(2) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to two equivalent K(1) and two equivalent Si(2) atoms.