LiAlSi2H2O7 crystallizes in the triclinic P1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 3-coordinate geometry to one H(3), one O(12), one O(2), and one O(5) atom. In the second Li site, Li(2) is bonded in a rectangular see-saw-like geometry to one O(1), one O(12), one O(5), and one O(7) atom. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(3), one O(4), one O(5), and one O(9) atom to form distorted AlO5 trigonal bipyramids that share  a cornercorner with one Al(2)HO5 octahedra,  a cornercorner with one Si(2)HO3 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and corners with two equivalent Si(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 26°. In the second Al site, Al(2) is bonded to one H(1), one O(11), one O(14), one O(3), one O(6), and one O(7) atom to form distorted AlHO5 octahedra that share  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Al(1)O5 trigonal bipyramid,  an edgeedge with one Si(2)HO3 tetrahedra, and  an edgeedge with one Si(1)O5 trigonal bipyramid. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(10), one O(11), one O(6), and one O(9) atom to form distorted SiO5 trigonal bipyramids that share  a cornercorner with one Si(2)HO3 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Al(1)O5 trigonal bipyramids, and  an edgeedge with one Al(2)HO5 octahedra. In the second Si site, Si(2) is bonded to one H(3), one O(14), one O(5), and one O(6) atom to form SiHO3 tetrahedra that share  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Al(1)O5 trigonal bipyramid,  a cornercorner with one Si(1)O5 trigonal bipyramid, and  an edgeedge with one Al(2)HO5 octahedra. In the third Si site, Si(3) is bonded to one O(11), one O(12), one O(13), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)HO5 octahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Si(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 77°. In the fourth Si site, Si(4) is bonded to one O(14), one O(2), one O(4), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)HO5 octahedra,  a cornercorner with one Si(2)HO3 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Al(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 41°. There are four inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one Al(2) 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 distorted L-shaped geometry to one Li(1) and one Si(2) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(2) atom. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a T-shaped geometry to one Li(2), one Al(1), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Li(1), one Si(4), and one H(4) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Al(1), one Al(2), and one O(13) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(4) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Li(1), one Li(2), one Al(1), and one Si(2) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Al(2), one Si(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Li(2), one Al(2), and one O(10) atom. In the eighth O site, O(8) is bonded in a bent 120 degrees geometry to one Si(3) and one Si(4) atom. In the ninth O site, O(9) is bonded in a 1-coordinate geometry to one Al(1), one Si(1), and one H(2) atom. In the tenth O site, O(10) is bonded in a distorted water-like geometry to one Si(1) and one O(7) atom. In the eleventh O site, O(11) is bonded in a trigonal non-coplanar geometry to one Al(2), one Si(1), and one Si(3) atom. In the twelfth O site, O(12) is bonded in a trigonal non-coplanar geometry to one Li(1), one Li(2), and one Si(3) atom. In the thirteenth O site, O(13) is bonded in a distorted single-bond geometry to one Si(3) and one O(3) atom. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one Al(2), one Si(2), and one Si(4) atom.
LiAlSi2H2O7 crystallizes in the triclinic P1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 3-coordinate geometry to one H(3), one O(12), one O(2), and one O(5) atom. The Li(1)-H(3) bond length is 2.24 Å. The Li(1)-O(12) bond length is 1.83 Å. The Li(1)-O(2) bond length is 2.13 Å. The Li(1)-O(5) bond length is 1.95 Å. In the second Li site, Li(2) is bonded in a rectangular see-saw-like geometry to one O(1), one O(12), one O(5), and one O(7) atom. The Li(2)-O(1) bond length is 2.07 Å. The Li(2)-O(12) bond length is 1.85 Å. The Li(2)-O(5) bond length is 2.16 Å. The Li(2)-O(7) bond length is 1.93 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(3), one O(4), one O(5), and one O(9) atom to form distorted AlO5 trigonal bipyramids that share  a cornercorner with one Al(2)HO5 octahedra,  a cornercorner with one Si(2)HO3 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and corners with two equivalent Si(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 26°. The Al(1)-O(1) bond length is 1.78 Å. The Al(1)-O(3) bond length is 1.89 Å. The Al(1)-O(4) bond length is 1.75 Å. The Al(1)-O(5) bond length is 1.83 Å. The Al(1)-O(9) bond length is 2.12 Å. In the second Al site, Al(2) is bonded to one H(1), one O(11), one O(14), one O(3), one O(6), and one O(7) atom to form distorted AlHO5 octahedra that share  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Al(1)O5 trigonal bipyramid,  an edgeedge with one Si(2)HO3 tetrahedra, and  an edgeedge with one Si(1)O5 trigonal bipyramid. The Al(2)-H(1) bond length is 1.62 Å. The Al(2)-O(11) bond length is 1.99 Å. The Al(2)-O(14) bond length is 2.10 Å. The Al(2)-O(3) bond length is 2.04 Å. The Al(2)-O(6) bond length is 2.00 Å. The Al(2)-O(7) bond length is 1.81 Å. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(10), one O(11), one O(6), and one O(9) atom to form distorted SiO5 trigonal bipyramids that share  a cornercorner with one Si(2)HO3 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Al(1)O5 trigonal bipyramids, and  an edgeedge with one Al(2)HO5 octahedra. The Si(1)-O(1) bond length is 1.63 Å. The Si(1)-O(10) bond length is 1.73 Å. The Si(1)-O(11) bond length is 1.76 Å. The Si(1)-O(6) bond length is 1.90 Å. The Si(1)-O(9) bond length is 1.72 Å. In the second Si site, Si(2) is bonded to one H(3), one O(14), one O(5), and one O(6) atom to form SiHO3 tetrahedra that share  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Al(1)O5 trigonal bipyramid,  a cornercorner with one Si(1)O5 trigonal bipyramid, and  an edgeedge with one Al(2)HO5 octahedra. The Si(2)-H(3) bond length is 1.46 Å. The Si(2)-O(14) bond length is 1.68 Å. The Si(2)-O(5) bond length is 1.63 Å. The Si(2)-O(6) bond length is 1.67 Å. In the third Si site, Si(3) is bonded to one O(11), one O(12), one O(13), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)HO5 octahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Si(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 77°. The Si(3)-O(11) bond length is 1.67 Å. The Si(3)-O(12) bond length is 1.57 Å. The Si(3)-O(13) bond length is 1.73 Å. The Si(3)-O(8) bond length is 1.65 Å. In the fourth Si site, Si(4) is bonded to one O(14), one O(2), one O(4), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)HO5 octahedra,  a cornercorner with one Si(2)HO3 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Al(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 41°. The Si(4)-O(14) bond length is 1.66 Å. The Si(4)-O(2) bond length is 1.66 Å. The Si(4)-O(4) bond length is 1.59 Å. The Si(4)-O(8) bond length is 1.63 Å. There are four inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one Al(2) atom. 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 0.98 Å. In the third H site, H(3) is bonded in a distorted L-shaped geometry to one Li(1) and one Si(2) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(2) atom. The H(4)-O(2) bond length is 0.98 Å. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a T-shaped geometry to one Li(2), one Al(1), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Li(1), one Si(4), and one H(4) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Al(1), one Al(2), and one O(13) atom. The O(3)-O(13) bond length is 1.49 Å. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(4) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Li(1), one Li(2), one Al(1), and one Si(2) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Al(2), one Si(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Li(2), one Al(2), and one O(10) atom. The O(7)-O(10) bond length is 1.47 Å. In the eighth O site, O(8) is bonded in a bent 120 degrees geometry to one Si(3) and one Si(4) atom. In the ninth O site, O(9) is bonded in a 1-coordinate geometry to one Al(1), one Si(1), and one H(2) atom. In the tenth O site, O(10) is bonded in a distorted water-like geometry to one Si(1) and one O(7) atom. In the eleventh O site, O(11) is bonded in a trigonal non-coplanar geometry to one Al(2), one Si(1), and one Si(3) atom. In the twelfth O site, O(12) is bonded in a trigonal non-coplanar geometry to one Li(1), one Li(2), and one Si(3) atom. In the thirteenth O site, O(13) is bonded in a distorted single-bond geometry to one Si(3) and one O(3) atom. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one Al(2), one Si(2), and one Si(4) atom.