K2Ge2O5 crystallizes in the monoclinic Cc space group. There are six inequivalent K sites. In the first K site, K(1) is bonded in a 6-coordinate geometry to one O(10), one O(3), one O(4), one O(5), one O(6), and one O(8) atom. In the second K site, K(2) is bonded to one O(12), one O(13), one O(15), one O(3), one O(5), and one O(6) atom to form KO6 octahedra that share  a cornercorner with one Ge(1)O4 tetrahedra,  a cornercorner with one Ge(2)O4 tetrahedra,  a cornercorner with one Ge(3)O4 tetrahedra,  a cornercorner with one Ge(4)O4 tetrahedra,  a cornercorner with one Ge(5)O4 tetrahedra, and  a cornercorner with one Ge(6)O4 tetrahedra. In the third K site, K(3) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(13), one O(15), one O(2), one O(4), one O(6), and one O(7) atom. In the fourth K site, K(4) is bonded in a 8-coordinate geometry to one O(1), one O(11), one O(12), one O(14), one O(3), one O(5), one O(7), and one O(9) atom. In the fifth K site, K(5) is bonded in a 5-coordinate geometry to one O(1), one O(12), one O(13), one O(3), and one O(6) atom. In the sixth K site, K(6) is bonded in a 7-coordinate geometry to one O(12), one O(13), one O(15), one O(5), one O(9), and two equivalent O(14) atoms. There are six inequivalent Ge sites. In the first Ge site, Ge(1) is bonded to one O(1), one O(11), one O(2), and one O(3) atom to form GeO4 tetrahedra that share  a cornercorner with one K(2)O6 octahedra,  a cornercorner with one Ge(6)O4 tetrahedra, and corners with two equivalent Ge(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 3°. In the second Ge site, Ge(2) is bonded to one O(4), one O(5), one O(7), and one O(8) atom to form GeO4 tetrahedra that share  a cornercorner with one K(2)O6 octahedra,  a cornercorner with one Ge(3)O4 tetrahedra,  a cornercorner with one Ge(4)O4 tetrahedra, and  a cornercorner with one Ge(6)O4 tetrahedra. The corner-sharing octahedral tilt angles are 34°. In the third Ge site, Ge(3) is bonded to one O(1), one O(15), one O(2), and one O(7) atom to form GeO4 tetrahedra that share  a cornercorner with one K(2)O6 octahedra,  a cornercorner with one Ge(2)O4 tetrahedra, and corners with two equivalent Ge(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 40°. In the fourth Ge site, Ge(4) is bonded to one O(10), one O(6), one O(8), and one O(9) atom to form GeO4 tetrahedra that share  a cornercorner with one K(2)O6 octahedra,  a cornercorner with one Ge(2)O4 tetrahedra, and corners with two equivalent Ge(5)O4 tetrahedra. The corner-sharing octahedral tilt angles are 23°. In the fifth Ge site, Ge(5) is bonded to one O(10), one O(12), one O(14), and one O(9) atom to form GeO4 tetrahedra that share  a cornercorner with one K(2)O6 octahedra,  a cornercorner with one Ge(6)O4 tetrahedra, and corners with two equivalent Ge(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 50°. In the sixth Ge site, Ge(6) is bonded to one O(11), one O(13), one O(14), and one O(4) atom to form GeO4 tetrahedra that share  a cornercorner with one K(2)O6 octahedra,  a cornercorner with one Ge(1)O4 tetrahedra,  a cornercorner with one Ge(2)O4 tetrahedra, and  a cornercorner with one Ge(5)O4 tetrahedra. The corner-sharing octahedral tilt angles are 18°. There are fifteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one K(4), one K(5), one Ge(1), and one Ge(3) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one K(3), one Ge(1), and one Ge(3) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one K(1), one K(2), one K(4), one K(5), and one Ge(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal pyramidal geometry to one K(1), one K(3), one Ge(2), and one Ge(6) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one K(1), one K(2), one K(4), one K(6), and one Ge(2) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one K(1), one K(2), one K(3), one K(5), and one Ge(4) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one K(3), one K(4), one Ge(2), and one Ge(3) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one K(1), one Ge(2), and one Ge(4) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to one K(4), one K(6), one Ge(4), and one Ge(5) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one K(1), one K(3), one Ge(4), and one Ge(5) atom. In the eleventh O site, O(11) is bonded in a 2-coordinate geometry to one K(3), one K(4), one Ge(1), and one Ge(6) atom. In the twelfth O site, O(12) is bonded in a 5-coordinate geometry to one K(2), one K(4), one K(5), one K(6), and one Ge(5) atom. In the thirteenth O site, O(13) is bonded in a 5-coordinate geometry to one K(2), one K(3), one K(5), one K(6), and one Ge(6) atom. In the fourteenth O site, O(14) is bonded in a distorted bent 120 degrees geometry to one K(4), two equivalent K(6), one Ge(5), and one Ge(6) atom. In the fifteenth O site, O(15) is bonded in a distorted rectangular see-saw-like geometry to one K(2), one K(3), one K(6), and one Ge(3) atom.
K2Ge2O5 crystallizes in the monoclinic Cc space group. There are six inequivalent K sites. In the first K site, K(1) is bonded in a 6-coordinate geometry to one O(10), one O(3), one O(4), one O(5), one O(6), and one O(8) atom. The K(1)-O(10) bond length is 3.32 Å. The K(1)-O(3) bond length is 2.71 Å. The K(1)-O(4) bond length is 2.83 Å. The K(1)-O(5) bond length is 3.01 Å. The K(1)-O(6) bond length is 2.70 Å. The K(1)-O(8) bond length is 2.75 Å. In the second K site, K(2) is bonded to one O(12), one O(13), one O(15), one O(3), one O(5), and one O(6) atom to form KO6 octahedra that share  a cornercorner with one Ge(1)O4 tetrahedra,  a cornercorner with one Ge(2)O4 tetrahedra,  a cornercorner with one Ge(3)O4 tetrahedra,  a cornercorner with one Ge(4)O4 tetrahedra,  a cornercorner with one Ge(5)O4 tetrahedra, and  a cornercorner with one Ge(6)O4 tetrahedra. The K(2)-O(12) bond length is 2.69 Å. The K(2)-O(13) bond length is 2.71 Å. The K(2)-O(15) bond length is 2.62 Å. The K(2)-O(3) bond length is 2.83 Å. The K(2)-O(5) bond length is 2.76 Å. The K(2)-O(6) bond length is 2.72 Å. In the third K site, K(3) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(13), one O(15), one O(2), one O(4), one O(6), and one O(7) atom. The K(3)-O(10) bond length is 2.76 Å. The K(3)-O(11) bond length is 3.10 Å. The K(3)-O(13) bond length is 3.09 Å. The K(3)-O(15) bond length is 2.76 Å. The K(3)-O(2) bond length is 2.95 Å. The K(3)-O(4) bond length is 2.88 Å. The K(3)-O(6) bond length is 3.00 Å. The K(3)-O(7) bond length is 3.09 Å. In the fourth K site, K(4) is bonded in a 8-coordinate geometry to one O(1), one O(11), one O(12), one O(14), one O(3), one O(5), one O(7), and one O(9) atom. The K(4)-O(1) bond length is 3.21 Å. The K(4)-O(11) bond length is 3.07 Å. The K(4)-O(12) bond length is 2.70 Å. The K(4)-O(14) bond length is 3.13 Å. The K(4)-O(3) bond length is 2.97 Å. The K(4)-O(5) bond length is 2.73 Å. The K(4)-O(7) bond length is 2.80 Å. The K(4)-O(9) bond length is 2.96 Å. In the fifth K site, K(5) is bonded in a 5-coordinate geometry to one O(1), one O(12), one O(13), one O(3), and one O(6) atom. The K(5)-O(1) bond length is 2.97 Å. The K(5)-O(12) bond length is 2.74 Å. The K(5)-O(13) bond length is 2.71 Å. The K(5)-O(3) bond length is 2.75 Å. The K(5)-O(6) bond length is 2.96 Å. In the sixth K site, K(6) is bonded in a 7-coordinate geometry to one O(12), one O(13), one O(15), one O(5), one O(9), and two equivalent O(14) atoms. The K(6)-O(12) bond length is 2.89 Å. The K(6)-O(13) bond length is 2.88 Å. The K(6)-O(15) bond length is 2.63 Å. The K(6)-O(5) bond length is 2.68 Å. The K(6)-O(9) bond length is 2.94 Å. There is one shorter (3.10 Å) and one longer (3.22 Å) K(6)-O(14) bond length. There are six inequivalent Ge sites. In the first Ge site, Ge(1) is bonded to one O(1), one O(11), one O(2), and one O(3) atom to form GeO4 tetrahedra that share  a cornercorner with one K(2)O6 octahedra,  a cornercorner with one Ge(6)O4 tetrahedra, and corners with two equivalent Ge(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 3°. The Ge(1)-O(1) bond length is 1.82 Å. The Ge(1)-O(11) bond length is 1.82 Å. The Ge(1)-O(2) bond length is 1.82 Å. The Ge(1)-O(3) bond length is 1.70 Å. In the second Ge site, Ge(2) is bonded to one O(4), one O(5), one O(7), and one O(8) atom to form GeO4 tetrahedra that share  a cornercorner with one K(2)O6 octahedra,  a cornercorner with one Ge(3)O4 tetrahedra,  a cornercorner with one Ge(4)O4 tetrahedra, and  a cornercorner with one Ge(6)O4 tetrahedra. The corner-sharing octahedral tilt angles are 34°. The Ge(2)-O(4) bond length is 1.82 Å. The Ge(2)-O(5) bond length is 1.69 Å. The Ge(2)-O(7) bond length is 1.82 Å. The Ge(2)-O(8) bond length is 1.80 Å. In the third Ge site, Ge(3) is bonded to one O(1), one O(15), one O(2), and one O(7) atom to form GeO4 tetrahedra that share  a cornercorner with one K(2)O6 octahedra,  a cornercorner with one Ge(2)O4 tetrahedra, and corners with two equivalent Ge(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 40°. The Ge(3)-O(1) bond length is 1.81 Å. The Ge(3)-O(15) bond length is 1.69 Å. The Ge(3)-O(2) bond length is 1.83 Å. The Ge(3)-O(7) bond length is 1.82 Å. In the fourth Ge site, Ge(4) is bonded to one O(10), one O(6), one O(8), and one O(9) atom to form GeO4 tetrahedra that share  a cornercorner with one K(2)O6 octahedra,  a cornercorner with one Ge(2)O4 tetrahedra, and corners with two equivalent Ge(5)O4 tetrahedra. The corner-sharing octahedral tilt angles are 23°. The Ge(4)-O(10) bond length is 1.83 Å. The Ge(4)-O(6) bond length is 1.71 Å. The Ge(4)-O(8) bond length is 1.79 Å. The Ge(4)-O(9) bond length is 1.80 Å. In the fifth Ge site, Ge(5) is bonded to one O(10), one O(12), one O(14), and one O(9) atom to form GeO4 tetrahedra that share  a cornercorner with one K(2)O6 octahedra,  a cornercorner with one Ge(6)O4 tetrahedra, and corners with two equivalent Ge(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 50°. The Ge(5)-O(10) bond length is 1.81 Å. The Ge(5)-O(12) bond length is 1.70 Å. The Ge(5)-O(14) bond length is 1.82 Å. The Ge(5)-O(9) bond length is 1.81 Å. In the sixth Ge site, Ge(6) is bonded to one O(11), one O(13), one O(14), and one O(4) atom to form GeO4 tetrahedra that share  a cornercorner with one K(2)O6 octahedra,  a cornercorner with one Ge(1)O4 tetrahedra,  a cornercorner with one Ge(2)O4 tetrahedra, and  a cornercorner with one Ge(5)O4 tetrahedra. The corner-sharing octahedral tilt angles are 18°. The Ge(6)-O(11) bond length is 1.81 Å. The Ge(6)-O(13) bond length is 1.70 Å. The Ge(6)-O(14) bond length is 1.80 Å. The Ge(6)-O(4) bond length is 1.83 Å. There are fifteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one K(4), one K(5), one Ge(1), and one Ge(3) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one K(3), one Ge(1), and one Ge(3) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one K(1), one K(2), one K(4), one K(5), and one Ge(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal pyramidal geometry to one K(1), one K(3), one Ge(2), and one Ge(6) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one K(1), one K(2), one K(4), one K(6), and one Ge(2) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one K(1), one K(2), one K(3), one K(5), and one Ge(4) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one K(3), one K(4), one Ge(2), and one Ge(3) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one K(1), one Ge(2), and one Ge(4) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to one K(4), one K(6), one Ge(4), and one Ge(5) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one K(1), one K(3), one Ge(4), and one Ge(5) atom. In the eleventh O site, O(11) is bonded in a 2-coordinate geometry to one K(3), one K(4), one Ge(1), and one Ge(6) atom. In the twelfth O site, O(12) is bonded in a 5-coordinate geometry to one K(2), one K(4), one K(5), one K(6), and one Ge(5) atom. In the thirteenth O site, O(13) is bonded in a 5-coordinate geometry to one K(2), one K(3), one K(5), one K(6), and one Ge(6) atom. In the fourteenth O site, O(14) is bonded in a distorted bent 120 degrees geometry to one K(4), two equivalent K(6), one Ge(5), and one Ge(6) atom. In the fifteenth O site, O(15) is bonded in a distorted rectangular see-saw-like geometry to one K(2), one K(3), one K(6), and one Ge(3) atom.