KBe2B3O7 crystallizes in the monoclinic C2/c space group. K(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(3), and four equivalent O(4) atoms. Be(1) is bonded to one O(1), one O(4), and two equivalent O(2) atoms to form a mixture of corner and edge-sharing BeO4 tetrahedra. There are two inequivalent B sites. In the first B site, B(1) is bonded in a trigonal planar geometry to one O(1) and two equivalent O(3) atoms. In the second B site, B(2) is bonded in a trigonal planar geometry to one O(2), one O(3), and one O(4) atom. There are four inequivalent O sites. In the first O site, O(4) is bonded in a 2-coordinate geometry to two equivalent K(1), one Be(1), and one B(2) atom. In the second O site, O(1) is bonded in a trigonal planar geometry to two equivalent Be(1) and one B(1) atom. In the third O site, O(2) is bonded in a 3-coordinate geometry to one K(1), two equivalent Be(1), and one B(2) atom. In the fourth O site, O(3) is bonded in a distorted bent 120 degrees geometry to one K(1), one B(1), and one B(2) atom.
KBe2B3O7 crystallizes in the monoclinic C2/c space group. K(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(3), and four equivalent O(4) atoms. Both K(1)-O(2) bond lengths are 2.81 Å. Both K(1)-O(3) bond lengths are 2.86 Å. There are two shorter (2.87 Å) and two longer (2.90 Å) K(1)-O(4) bond lengths. Be(1) is bonded to one O(1), one O(4), and two equivalent O(2) atoms to form a mixture of corner and edge-sharing BeO4 tetrahedra. The Be(1)-O(1) bond length is 1.68 Å. The Be(1)-O(4) bond length is 1.58 Å. There is one shorter (1.66 Å) and one longer (1.70 Å) Be(1)-O(2) bond length. There are two inequivalent B sites. In the first B site, B(1) is bonded in a trigonal planar geometry to one O(1) and two equivalent O(3) atoms. The B(1)-O(1) bond length is 1.38 Å. Both B(1)-O(3) bond lengths are 1.39 Å. In the second B site, B(2) is bonded in a trigonal planar geometry to one O(2), one O(3), and one O(4) atom. The B(2)-O(2) bond length is 1.39 Å. The B(2)-O(3) bond length is 1.42 Å. The B(2)-O(4) bond length is 1.34 Å. There are four inequivalent O sites. In the first O site, O(4) is bonded in a 2-coordinate geometry to two equivalent K(1), one Be(1), and one B(2) atom. In the second O site, O(1) is bonded in a trigonal planar geometry to two equivalent Be(1) and one B(1) atom. In the third O site, O(2) is bonded in a 3-coordinate geometry to one K(1), two equivalent Be(1), and one B(2) atom. In the fourth O site, O(3) is bonded in a distorted bent 120 degrees geometry to one K(1), one B(1), and one B(2) atom.