Li2Cu2Si8O19 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 O(16), one O(17), and one O(7) atom. In the second Li site, Li(2) is bonded in a distorted trigonal non-coplanar geometry to one O(12), one O(17), and one O(3) atom. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(12), one O(13), one O(4), and one O(6) atom to form CuO4 trigonal pyramids that share  a cornercorner with one Si(5)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, and corners with two equivalent Cu(2)O4 trigonal pyramids. In the second Cu site, Cu(2) is bonded to one O(13), one O(15), one O(6), and one O(7) atom to form CuO4 trigonal pyramids that share  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(6)O4 tetrahedra, and corners with two equivalent Cu(1)O4 trigonal pyramids. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(10), one O(2), and one O(5) atom to form corner-sharing SiO4 tetrahedra. In the second Si site, Si(2) is bonded to one O(18), one O(19), one O(3), and one O(8) atom to form corner-sharing SiO4 tetrahedra. In the third Si site, Si(3) is bonded to one O(17), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra,  a cornercorner with one Cu(2)O4 trigonal pyramid, and corners with two equivalent Cu(1)O4 trigonal pyramids. In the fourth Si site, Si(4) is bonded to one O(11), one O(5), one O(7), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(7)O4 tetrahedra,  a cornercorner with one Si(8)O4 tetrahedra, and  a cornercorner with one Cu(2)O4 trigonal pyramid. In the fifth Si site, Si(5) is bonded to one O(10), one O(12), one O(14), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(8)O4 tetrahedra, and  a cornercorner with one Cu(1)O4 trigonal pyramid. In the sixth Si site, Si(6) is bonded to one O(13), one O(15), one O(16), and one O(17) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(7)O4 tetrahedra,  a cornercorner with one Cu(1)O4 trigonal pyramid, and corners with two equivalent Cu(2)O4 trigonal pyramids. In the seventh Si site, Si(7) is bonded to one O(1), one O(11), one O(16), and one O(2) atom to form corner-sharing SiO4 tetrahedra. In the eighth Si site, Si(8) is bonded to one O(14), one O(18), one O(19), and one O(9) atom to form corner-sharing SiO4 tetrahedra. There are nineteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(7) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(7) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Li(2), one Si(2), and one Si(3) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Cu(1) and one Si(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(4) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Cu(1), one Cu(2), and one Si(3) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Li(1), one Cu(2), and one Si(4) atom. In the eighth O site, O(8) is bonded in a linear geometry to one Si(2) and one Si(5) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Si(4) and one Si(8) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(5) atom. In the eleventh O site, O(11) is bonded in a linear geometry to one Si(4) and one Si(7) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Li(2), one Cu(1), and one Si(5) atom. In the thirteenth O site, O(13) is bonded in a trigonal planar geometry to one Cu(1), one Cu(2), and one Si(6) atom. In the fourteenth O site, O(14) is bonded in a bent 150 degrees geometry to one Si(5) and one Si(8) atom. In the fifteenth O site, O(15) is bonded in a water-like geometry to one Cu(2) and one Si(6) atom. In the sixteenth O site, O(16) is bonded in a 3-coordinate geometry to one Li(1), one Si(6), and one Si(7) atom. In the seventeenth O site, O(17) is bonded in a distorted tetrahedral geometry to one Li(1), one Li(2), one Si(3), and one Si(6) atom. In the eighteenth O site, O(18) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(8) atom. In the nineteenth O site, O(19) is bonded in a bent 120 degrees geometry to one Si(2) and one Si(8) atom.
Li2Cu2Si8O19 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 O(16), one O(17), and one O(7) atom. The Li(1)-O(16) bond length is 2.19 Å. The Li(1)-O(17) bond length is 2.11 Å. The Li(1)-O(7) bond length is 2.11 Å. In the second Li site, Li(2) is bonded in a distorted trigonal non-coplanar geometry to one O(12), one O(17), and one O(3) atom. The Li(2)-O(12) bond length is 2.05 Å. The Li(2)-O(17) bond length is 2.11 Å. The Li(2)-O(3) bond length is 2.17 Å. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(12), one O(13), one O(4), and one O(6) atom to form CuO4 trigonal pyramids that share  a cornercorner with one Si(5)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, and corners with two equivalent Cu(2)O4 trigonal pyramids. The Cu(1)-O(12) bond length is 1.94 Å. The Cu(1)-O(13) bond length is 2.03 Å. The Cu(1)-O(4) bond length is 1.94 Å. The Cu(1)-O(6) bond length is 2.00 Å. In the second Cu site, Cu(2) is bonded to one O(13), one O(15), one O(6), and one O(7) atom to form CuO4 trigonal pyramids that share  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(6)O4 tetrahedra, and corners with two equivalent Cu(1)O4 trigonal pyramids. The Cu(2)-O(13) bond length is 2.02 Å. The Cu(2)-O(15) bond length is 1.93 Å. The Cu(2)-O(6) bond length is 2.04 Å. The Cu(2)-O(7) bond length is 1.94 Å. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(10), one O(2), and one O(5) atom to form corner-sharing SiO4 tetrahedra. The Si(1)-O(1) bond length is 1.64 Å. The Si(1)-O(10) bond length is 1.63 Å. The Si(1)-O(2) bond length is 1.62 Å. The Si(1)-O(5) bond length is 1.63 Å. In the second Si site, Si(2) is bonded to one O(18), one O(19), one O(3), and one O(8) atom to form corner-sharing SiO4 tetrahedra. The Si(2)-O(18) bond length is 1.62 Å. The Si(2)-O(19) bond length is 1.63 Å. The Si(2)-O(3) bond length is 1.64 Å. The Si(2)-O(8) bond length is 1.62 Å. In the third Si site, Si(3) is bonded to one O(17), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra,  a cornercorner with one Cu(2)O4 trigonal pyramid, and corners with two equivalent Cu(1)O4 trigonal pyramids. The Si(3)-O(17) bond length is 1.68 Å. The Si(3)-O(3) bond length is 1.66 Å. The Si(3)-O(4) bond length is 1.61 Å. The Si(3)-O(6) bond length is 1.63 Å. In the fourth Si site, Si(4) is bonded to one O(11), one O(5), one O(7), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(7)O4 tetrahedra,  a cornercorner with one Si(8)O4 tetrahedra, and  a cornercorner with one Cu(2)O4 trigonal pyramid. The Si(4)-O(11) bond length is 1.65 Å. The Si(4)-O(5) bond length is 1.65 Å. The Si(4)-O(7) bond length is 1.62 Å. The Si(4)-O(9) bond length is 1.65 Å. In the fifth Si site, Si(5) is bonded to one O(10), one O(12), one O(14), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(8)O4 tetrahedra, and  a cornercorner with one Cu(1)O4 trigonal pyramid. The Si(5)-O(10) bond length is 1.65 Å. The Si(5)-O(12) bond length is 1.62 Å. The Si(5)-O(14) bond length is 1.64 Å. The Si(5)-O(8) bond length is 1.64 Å. In the sixth Si site, Si(6) is bonded to one O(13), one O(15), one O(16), and one O(17) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(7)O4 tetrahedra,  a cornercorner with one Cu(1)O4 trigonal pyramid, and corners with two equivalent Cu(2)O4 trigonal pyramids. The Si(6)-O(13) bond length is 1.64 Å. The Si(6)-O(15) bond length is 1.61 Å. The Si(6)-O(16) bond length is 1.66 Å. The Si(6)-O(17) bond length is 1.68 Å. In the seventh Si site, Si(7) is bonded to one O(1), one O(11), one O(16), and one O(2) atom to form corner-sharing SiO4 tetrahedra. The Si(7)-O(1) bond length is 1.63 Å. The Si(7)-O(11) bond length is 1.61 Å. The Si(7)-O(16) bond length is 1.64 Å. The Si(7)-O(2) bond length is 1.62 Å. In the eighth Si site, Si(8) is bonded to one O(14), one O(18), one O(19), and one O(9) atom to form corner-sharing SiO4 tetrahedra. The Si(8)-O(14) bond length is 1.63 Å. The Si(8)-O(18) bond length is 1.62 Å. The Si(8)-O(19) bond length is 1.64 Å. The Si(8)-O(9) bond length is 1.63 Å. There are nineteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(7) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(7) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Li(2), one Si(2), and one Si(3) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Cu(1) and one Si(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(4) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Cu(1), one Cu(2), and one Si(3) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Li(1), one Cu(2), and one Si(4) atom. In the eighth O site, O(8) is bonded in a linear geometry to one Si(2) and one Si(5) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Si(4) and one Si(8) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(5) atom. In the eleventh O site, O(11) is bonded in a linear geometry to one Si(4) and one Si(7) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Li(2), one Cu(1), and one Si(5) atom. In the thirteenth O site, O(13) is bonded in a trigonal planar geometry to one Cu(1), one Cu(2), and one Si(6) atom. In the fourteenth O site, O(14) is bonded in a bent 150 degrees geometry to one Si(5) and one Si(8) atom. In the fifteenth O site, O(15) is bonded in a water-like geometry to one Cu(2) and one Si(6) atom. In the sixteenth O site, O(16) is bonded in a 3-coordinate geometry to one Li(1), one Si(6), and one Si(7) atom. In the seventeenth O site, O(17) is bonded in a distorted tetrahedral geometry to one Li(1), one Li(2), one Si(3), and one Si(6) atom. In the eighteenth O site, O(18) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(8) atom. In the nineteenth O site, O(19) is bonded in a bent 120 degrees geometry to one Si(2) and one Si(8) atom.