K2GeTe4 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one Te(2), two equivalent Te(1), two equivalent Te(3), and two equivalent Te(4) atoms. In the second K site, K(2) is bonded in a 7-coordinate geometry to one Te(4), three equivalent Te(2), and three equivalent Te(3) atoms. Ge(1) is bonded in a distorted tetrahedral geometry to one Te(1), one Te(2), one Te(3), and one Te(4) atom. There are four inequivalent Te sites. In the first Te site, Te(1) is bonded in a 4-coordinate geometry to two equivalent K(1), one Ge(1), and one Te(4) atom. In the second Te site, Te(2) is bonded to one K(1), three equivalent K(2), and one Ge(1) atom to form distorted TeK4Ge trigonal bipyramids that share corners with two equivalent Te(3)K5Ge pentagonal pyramids, corners with four equivalent Te(2)K4Ge trigonal bipyramids, edges with five equivalent Te(3)K5Ge pentagonal pyramids, and  an edgeedge with one Te(2)K4Ge trigonal bipyramid. In the third Te site, Te(3) is bonded to two equivalent K(1), three equivalent K(2), and one Ge(1) atom to form distorted TeK5Ge pentagonal pyramids that share corners with two equivalent Te(3)K5Ge pentagonal pyramids, corners with two equivalent Te(2)K4Ge trigonal bipyramids, edges with three equivalent Te(3)K5Ge pentagonal pyramids, and edges with five equivalent Te(2)K4Ge trigonal bipyramids. In the fourth Te site, Te(4) is bonded in a 5-coordinate geometry to one K(2), two equivalent K(1), one Ge(1), and one Te(1) atom.
K2GeTe4 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one Te(2), two equivalent Te(1), two equivalent Te(3), and two equivalent Te(4) atoms. The K(1)-Te(2) bond length is 3.60 Å. There is one shorter (3.67 Å) and one longer (3.93 Å) K(1)-Te(1) bond length. There is one shorter (3.60 Å) and one longer (3.63 Å) K(1)-Te(3) bond length. There is one shorter (3.86 Å) and one longer (4.00 Å) K(1)-Te(4) bond length. In the second K site, K(2) is bonded in a 7-coordinate geometry to one Te(4), three equivalent Te(2), and three equivalent Te(3) atoms. The K(2)-Te(4) bond length is 3.86 Å. There are a spread of K(2)-Te(2) bond distances ranging from 3.63-3.77 Å. There are a spread of K(2)-Te(3) bond distances ranging from 3.66-3.77 Å. Ge(1) is bonded in a distorted tetrahedral geometry to one Te(1), one Te(2), one Te(3), and one Te(4) atom. The Ge(1)-Te(1) bond length is 2.66 Å. The Ge(1)-Te(2) bond length is 2.52 Å. The Ge(1)-Te(3) bond length is 2.56 Å. The Ge(1)-Te(4) bond length is 2.63 Å. There are four inequivalent Te sites. In the first Te site, Te(1) is bonded in a 4-coordinate geometry to two equivalent K(1), one Ge(1), and one Te(4) atom. The Te(1)-Te(4) bond length is 2.76 Å. In the second Te site, Te(2) is bonded to one K(1), three equivalent K(2), and one Ge(1) atom to form distorted TeK4Ge trigonal bipyramids that share corners with two equivalent Te(3)K5Ge pentagonal pyramids, corners with four equivalent Te(2)K4Ge trigonal bipyramids, edges with five equivalent Te(3)K5Ge pentagonal pyramids, and  an edgeedge with one Te(2)K4Ge trigonal bipyramid. In the third Te site, Te(3) is bonded to two equivalent K(1), three equivalent K(2), and one Ge(1) atom to form distorted TeK5Ge pentagonal pyramids that share corners with two equivalent Te(3)K5Ge pentagonal pyramids, corners with two equivalent Te(2)K4Ge trigonal bipyramids, edges with three equivalent Te(3)K5Ge pentagonal pyramids, and edges with five equivalent Te(2)K4Ge trigonal bipyramids. In the fourth Te site, Te(4) is bonded in a 5-coordinate geometry to one K(2), two equivalent K(1), one Ge(1), and one Te(1) atom.