K3GeCPO7 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms. In the second K site, K(2) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form distorted KO7 pentagonal bipyramids that share corners with two equivalent K(2)O7 pentagonal bipyramids, corners with two equivalent P(1)O4 tetrahedra,  an edgeedge with one K(2)O7 pentagonal bipyramid,  an edgeedge with one P(1)O4 tetrahedra, and  a faceface with one K(2)O7 pentagonal bipyramid. Ge(1) is bonded in a 5-coordinate geometry to one O(2), one O(5), one O(6), and two equivalent O(4) atoms. C(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. P(1) is bonded to one O(5), one O(6), and two equivalent O(4) atoms to form PO4 tetrahedra that share corners with four equivalent K(2)O7 pentagonal bipyramids and edges with two equivalent K(2)O7 pentagonal bipyramids. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to two equivalent K(1), two equivalent K(2), and one C(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one K(1), two equivalent K(2), one Ge(1), and one C(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one K(1), two equivalent K(2), and one C(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one K(1), two equivalent K(2), one Ge(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent K(2), one Ge(1), and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(2), one Ge(1), and one P(1) atom.
K3GeCPO7 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms. The K(1)-O(2) bond length is 2.78 Å. The K(1)-O(3) bond length is 2.76 Å. There is one shorter (2.77 Å) and one longer (2.85 Å) K(1)-O(1) bond length. Both K(1)-O(4) bond lengths are 2.81 Å. In the second K site, K(2) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form distorted KO7 pentagonal bipyramids that share corners with two equivalent K(2)O7 pentagonal bipyramids, corners with two equivalent P(1)O4 tetrahedra,  an edgeedge with one K(2)O7 pentagonal bipyramid,  an edgeedge with one P(1)O4 tetrahedra, and  a faceface with one K(2)O7 pentagonal bipyramid. The K(2)-O(1) bond length is 2.73 Å. The K(2)-O(2) bond length is 2.81 Å. The K(2)-O(3) bond length is 2.74 Å. The K(2)-O(5) bond length is 2.77 Å. The K(2)-O(6) bond length is 2.69 Å. There is one shorter (2.89 Å) and one longer (3.01 Å) K(2)-O(4) bond length. Ge(1) is bonded in a 5-coordinate geometry to one O(2), one O(5), one O(6), and two equivalent O(4) atoms. The Ge(1)-O(2) bond length is 2.54 Å. The Ge(1)-O(5) bond length is 2.20 Å. The Ge(1)-O(6) bond length is 2.18 Å. Both Ge(1)-O(4) bond lengths are 2.44 Å. C(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. The C(1)-O(1) bond length is 1.31 Å. The C(1)-O(2) bond length is 1.30 Å. The C(1)-O(3) bond length is 1.30 Å. P(1) is bonded to one O(5), one O(6), and two equivalent O(4) atoms to form PO4 tetrahedra that share corners with four equivalent K(2)O7 pentagonal bipyramids and edges with two equivalent K(2)O7 pentagonal bipyramids. The P(1)-O(5) bond length is 1.57 Å. The P(1)-O(6) bond length is 1.57 Å. Both P(1)-O(4) bond lengths are 1.56 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to two equivalent K(1), two equivalent K(2), and one C(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one K(1), two equivalent K(2), one Ge(1), and one C(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one K(1), two equivalent K(2), and one C(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one K(1), two equivalent K(2), one Ge(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent K(2), one Ge(1), and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(2), one Ge(1), and one P(1) atom.