CaB2H10O9 crystallizes in the triclinic P-1 space group. Ca(1) is bonded to one O(1), one O(3), one O(4), one O(6), one O(7), and two equivalent O(5) atoms to form distorted CaO7 pentagonal bipyramids that share corners with two equivalent B(1)O4 tetrahedra, corners with two equivalent B(2)O4 tetrahedra,  an edgeedge with one Ca(1)O7 pentagonal bipyramid, and  an edgeedge with one B(1)O4 tetrahedra. There are two inequivalent B sites. In the first B site, B(1) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form BO4 tetrahedra that share corners with two equivalent Ca(1)O7 pentagonal bipyramids,  a cornercorner with one B(2)O4 tetrahedra, and  an edgeedge with one Ca(1)O7 pentagonal bipyramid. In the second B site, B(2) is bonded to one O(6), one O(7), one O(8), and one O(9) atom to form BO4 tetrahedra that share corners with two equivalent Ca(1)O7 pentagonal bipyramids and  a cornercorner with one B(1)O4 tetrahedra. There are ten inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one O(2) and one O(8) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(2) atom. In the third H site, H(3) is bonded in a single-bond geometry to one O(8) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(9) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(3) atom. In the sixth H site, H(6) is bonded in a single-bond geometry to one O(4) atom. In the seventh H site, H(7) is bonded in a single-bond geometry to one O(1) atom. In the eighth H site, H(8) is bonded in a single-bond geometry to one O(7) atom. In the ninth H site, H(9) is bonded in a single-bond geometry to one O(5) atom. In the tenth H site, H(10) is bonded in a distorted single-bond geometry to one O(5) and one O(8) atom. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Ca(1), one B(1), and one H(7) atom. In the second O site, O(2) is bonded in a water-like geometry to one H(1) and one H(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one B(1), and one H(5) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Ca(1), one B(1), and one H(6) atom. In the fifth O site, O(5) is bonded in a water-like geometry to two equivalent Ca(1), one H(10), and one H(9) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ca(1), one B(1), and one B(2) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one Ca(1), one B(2), and one H(8) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one B(2), one H(1), one H(10), and one H(3) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to one B(2) and one H(4) atom.
CaB2H10O9 crystallizes in the triclinic P-1 space group. Ca(1) is bonded to one O(1), one O(3), one O(4), one O(6), one O(7), and two equivalent O(5) atoms to form distorted CaO7 pentagonal bipyramids that share corners with two equivalent B(1)O4 tetrahedra, corners with two equivalent B(2)O4 tetrahedra,  an edgeedge with one Ca(1)O7 pentagonal bipyramid, and  an edgeedge with one B(1)O4 tetrahedra. The Ca(1)-O(1) bond length is 2.42 Å. The Ca(1)-O(3) bond length is 2.36 Å. The Ca(1)-O(4) bond length is 2.43 Å. The Ca(1)-O(6) bond length is 2.41 Å. The Ca(1)-O(7) bond length is 2.43 Å. There is one shorter (2.50 Å) and one longer (2.56 Å) Ca(1)-O(5) bond length. There are two inequivalent B sites. In the first B site, B(1) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form BO4 tetrahedra that share corners with two equivalent Ca(1)O7 pentagonal bipyramids,  a cornercorner with one B(2)O4 tetrahedra, and  an edgeedge with one Ca(1)O7 pentagonal bipyramid. The B(1)-O(1) bond length is 1.50 Å. The B(1)-O(3) bond length is 1.48 Å. The B(1)-O(4) bond length is 1.50 Å. The B(1)-O(6) bond length is 1.47 Å. In the second B site, B(2) is bonded to one O(6), one O(7), one O(8), and one O(9) atom to form BO4 tetrahedra that share corners with two equivalent Ca(1)O7 pentagonal bipyramids and  a cornercorner with one B(1)O4 tetrahedra. The B(2)-O(6) bond length is 1.45 Å. The B(2)-O(7) bond length is 1.50 Å. The B(2)-O(8) bond length is 1.51 Å. The B(2)-O(9) bond length is 1.50 Å. There are ten inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one O(2) and one O(8) atom. The H(1)-O(2) bond length is 1.01 Å. The H(1)-O(8) bond length is 1.65 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(2) atom. The H(2)-O(2) bond length is 1.01 Å. In the third H site, H(3) is bonded in a single-bond geometry to one O(8) atom. The H(3)-O(8) bond length is 0.98 Å. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(9) atom. The H(4)-O(9) bond length is 1.00 Å. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(3) atom. The H(5)-O(3) bond length is 0.99 Å. In the sixth H site, H(6) is bonded in a single-bond geometry to one O(4) atom. The H(6)-O(4) bond length is 0.99 Å. In the seventh H site, H(7) is bonded in a single-bond geometry to one O(1) atom. The H(7)-O(1) bond length is 0.99 Å. In the eighth H site, H(8) is bonded in a single-bond geometry to one O(7) atom. The H(8)-O(7) bond length is 1.00 Å. In the ninth H site, H(9) is bonded in a single-bond geometry to one O(5) atom. The H(9)-O(5) bond length is 0.99 Å. In the tenth H site, H(10) is bonded in a distorted single-bond geometry to one O(5) and one O(8) atom. The H(10)-O(5) bond length is 1.01 Å. The H(10)-O(8) bond length is 1.68 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Ca(1), one B(1), and one H(7) atom. In the second O site, O(2) is bonded in a water-like geometry to one H(1) and one H(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one B(1), and one H(5) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Ca(1), one B(1), and one H(6) atom. In the fifth O site, O(5) is bonded in a water-like geometry to two equivalent Ca(1), one H(10), and one H(9) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ca(1), one B(1), and one B(2) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one Ca(1), one B(2), and one H(8) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one B(2), one H(1), one H(10), and one H(3) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to one B(2) and one H(4) atom.