KSmGeSe4 crystallizes in the monoclinic P2_1 space group. K(1) is bonded in a 7-coordinate geometry to one Se(4), two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms. Sm(1) is bonded to one Se(3), two equivalent Se(1), two equivalent Se(2), and two equivalent Se(4) atoms to form distorted SmSe7 pentagonal bipyramids that share corners with two equivalent Sm(1)Se7 pentagonal bipyramids,  a cornercorner with one Ge(1)Se4 tetrahedra, edges with two equivalent Sm(1)Se7 pentagonal bipyramids, and edges with three equivalent Ge(1)Se4 tetrahedra. Ge(1) is bonded to one Se(1), one Se(2), one Se(3), and one Se(4) atom to form GeSe4 tetrahedra that share  a cornercorner with one Sm(1)Se7 pentagonal bipyramid and edges with three equivalent Sm(1)Se7 pentagonal bipyramids. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent K(1), two equivalent Sm(1), and one Ge(1) atom to form a mixture of distorted edge, corner, and face-sharing SeK2Sm2Ge square pyramids. In the second Se site, Se(2) is bonded to two equivalent K(1), two equivalent Sm(1), and one Ge(1) atom to form a mixture of distorted edge, corner, and face-sharing SeK2Sm2Ge square pyramids. In the third Se site, Se(3) is bonded in a distorted see-saw-like geometry to two equivalent K(1), one Sm(1), and one Ge(1) atom. In the fourth Se site, Se(4) is bonded in a distorted see-saw-like geometry to one K(1), two equivalent Sm(1), and one Ge(1) atom.
KSmGeSe4 crystallizes in the monoclinic P2_1 space group. K(1) is bonded in a 7-coordinate geometry to one Se(4), two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms. The K(1)-Se(4) bond length is 3.42 Å. There is one shorter (3.56 Å) and one longer (3.58 Å) K(1)-Se(1) bond length. There is one shorter (3.56 Å) and one longer (3.67 Å) K(1)-Se(2) bond length. There is one shorter (3.44 Å) and one longer (3.55 Å) K(1)-Se(3) bond length. Sm(1) is bonded to one Se(3), two equivalent Se(1), two equivalent Se(2), and two equivalent Se(4) atoms to form distorted SmSe7 pentagonal bipyramids that share corners with two equivalent Sm(1)Se7 pentagonal bipyramids,  a cornercorner with one Ge(1)Se4 tetrahedra, edges with two equivalent Sm(1)Se7 pentagonal bipyramids, and edges with three equivalent Ge(1)Se4 tetrahedra. The Sm(1)-Se(3) bond length is 2.98 Å. There is one shorter (3.07 Å) and one longer (3.08 Å) Sm(1)-Se(1) bond length. There is one shorter (3.01 Å) and one longer (3.03 Å) Sm(1)-Se(2) bond length. There is one shorter (3.01 Å) and one longer (3.11 Å) Sm(1)-Se(4) bond length. Ge(1) is bonded to one Se(1), one Se(2), one Se(3), and one Se(4) atom to form GeSe4 tetrahedra that share  a cornercorner with one Sm(1)Se7 pentagonal bipyramid and edges with three equivalent Sm(1)Se7 pentagonal bipyramids. The Ge(1)-Se(1) bond length is 2.39 Å. The Ge(1)-Se(2) bond length is 2.39 Å. The Ge(1)-Se(3) bond length is 2.35 Å. The Ge(1)-Se(4) bond length is 2.38 Å. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent K(1), two equivalent Sm(1), and one Ge(1) atom to form a mixture of distorted edge, corner, and face-sharing SeK2Sm2Ge square pyramids. In the second Se site, Se(2) is bonded to two equivalent K(1), two equivalent Sm(1), and one Ge(1) atom to form a mixture of distorted edge, corner, and face-sharing SeK2Sm2Ge square pyramids. In the third Se site, Se(3) is bonded in a distorted see-saw-like geometry to two equivalent K(1), one Sm(1), and one Ge(1) atom. In the fourth Se site, Se(4) is bonded in a distorted see-saw-like geometry to one K(1), two equivalent Sm(1), and one Ge(1) atom.