Ca2Mn2Si4H6O17 crystallizes in the monoclinic C2 space group. Ca(1) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(6), one O(7), and one O(9) atom. Mn(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(8) atoms to form MnO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra and edges with two equivalent Mn(1)O6 octahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with four equivalent Mn(1)O6 octahedra and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 49-59°. In the second Si site, Si(2) is bonded to one O(2), one O(5), one O(6), and one O(7) atom to form corner-sharing SiO4 tetrahedra. There are three inequivalent H sites. In the first H site, H(1) is bonded in a linear geometry to one O(6) and one O(7) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(9) atom. In the third H site, H(3) is bonded in a single-bond geometry to one O(8) and one O(9) atom. There are nine inequivalent O sites. In the first O site, O(3) is bonded in a distorted trigonal planar geometry to one Ca(1), one Mn(1), and one Si(1) atom. In the second O site, O(4) is bonded in a distorted trigonal planar geometry to one Ca(1), one Mn(1), and one Si(1) atom. In the third O site, O(5) is bonded in a bent 150 degrees geometry to two equivalent Si(2) atoms. In the fourth O site, O(6) is bonded in a 3-coordinate geometry to one Ca(1), one Si(2), and one H(1) atom. In the fifth O site, O(7) is bonded in a distorted trigonal planar geometry to one Ca(1), one Si(2), and one H(1) atom. In the sixth O site, O(8) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Mn(1) and one H(3) atom. In the seventh O site, O(9) is bonded in a distorted water-like geometry to one Ca(1), one H(2), and one H(3) atom. In the eighth O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1), two equivalent Mn(1), and one Si(1) atom. In the ninth O site, O(2) is bonded in a distorted trigonal planar geometry to one Ca(1), one Si(1), and one Si(2) atom.
Ca2Mn2Si4H6O17 crystallizes in the monoclinic C2 space group. Ca(1) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(6), one O(7), and one O(9) atom. The Ca(1)-O(1) bond length is 2.82 Å. The Ca(1)-O(2) bond length is 2.63 Å. The Ca(1)-O(3) bond length is 2.41 Å. The Ca(1)-O(4) bond length is 2.41 Å. The Ca(1)-O(6) bond length is 2.33 Å. The Ca(1)-O(7) bond length is 2.37 Å. The Ca(1)-O(9) bond length is 2.36 Å. Mn(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(8) atoms to form MnO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra and edges with two equivalent Mn(1)O6 octahedra. The Mn(1)-O(3) bond length is 1.96 Å. The Mn(1)-O(4) bond length is 1.95 Å. Both Mn(1)-O(1) bond lengths are 2.05 Å. Both Mn(1)-O(8) bond lengths are 1.89 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with four equivalent Mn(1)O6 octahedra and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 49-59°. The Si(1)-O(1) bond length is 1.68 Å. The Si(1)-O(2) bond length is 1.66 Å. The Si(1)-O(3) bond length is 1.63 Å. The Si(1)-O(4) bond length is 1.63 Å. In the second Si site, Si(2) is bonded to one O(2), one O(5), one O(6), and one O(7) atom to form corner-sharing SiO4 tetrahedra. The Si(2)-O(2) bond length is 1.67 Å. The Si(2)-O(5) bond length is 1.63 Å. The Si(2)-O(6) bond length is 1.61 Å. The Si(2)-O(7) bond length is 1.65 Å. There are three inequivalent H sites. In the first H site, H(1) is bonded in a linear geometry to one O(6) and one O(7) atom. The H(1)-O(6) bond length is 1.53 Å. The H(1)-O(7) bond length is 1.04 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(9) atom. The H(2)-O(9) bond length is 0.99 Å. In the third H site, H(3) is bonded in a single-bond geometry to one O(8) and one O(9) atom. The H(3)-O(8) bond length is 1.71 Å. The H(3)-O(9) bond length is 1.00 Å. There are nine inequivalent O sites. In the first O site, O(3) is bonded in a distorted trigonal planar geometry to one Ca(1), one Mn(1), and one Si(1) atom. In the second O site, O(4) is bonded in a distorted trigonal planar geometry to one Ca(1), one Mn(1), and one Si(1) atom. In the third O site, O(5) is bonded in a bent 150 degrees geometry to two equivalent Si(2) atoms. In the fourth O site, O(6) is bonded in a 3-coordinate geometry to one Ca(1), one Si(2), and one H(1) atom. In the fifth O site, O(7) is bonded in a distorted trigonal planar geometry to one Ca(1), one Si(2), and one H(1) atom. In the sixth O site, O(8) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Mn(1) and one H(3) atom. In the seventh O site, O(9) is bonded in a distorted water-like geometry to one Ca(1), one H(2), and one H(3) atom. In the eighth O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1), two equivalent Mn(1), and one Si(1) atom. In the ninth O site, O(2) is bonded in a distorted trigonal planar geometry to one Ca(1), one Si(1), and one Si(2) atom.