Na3TaGeSi3O12 crystallizes in the monoclinic Cc space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(1), one O(11), one O(12), one O(2), one O(5), and one O(6) atom. In the second Na site, Na(2) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(11), one O(12), one O(2), one O(7), one O(8), and one O(9) atom. In the third Na site, Na(3) is bonded in a 7-coordinate geometry to one O(11), one O(2), one O(5), one O(6), one O(7), and two equivalent O(4) atoms. Ta(1) is bonded to one O(10), one O(12), one O(2), one O(3), one O(6), and one O(7) atom to form TaO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. Ge(1) is bonded to one O(1), one O(11), one O(4), one O(5), one O(8), and one O(9) atom to form GeO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(11), one O(12), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent Ta(1)O6 octahedra and corners with two equivalent Ge(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 20-40°. In the second Si site, Si(2) is bonded to one O(2), one O(5), one O(7), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Ta(1)O6 octahedra and corners with two equivalent Ge(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 26-36°. In the third Si site, Si(3) is bonded to one O(1), one O(10), one O(6), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Ta(1)O6 octahedra and corners with two equivalent Ge(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 22-36°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Na(1), one Na(2), one Ge(1), and one Si(3) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Na(3), one Ta(1), and one Si(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Ta(1) and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to two equivalent Na(3), one Ge(1), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(3), one Ge(1), and one Si(2) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(3), one Ta(1), and one Si(3) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one Na(2), one Na(3), one Ta(1), and one Si(2) atom. In the eighth O site, O(8) is bonded in a distorted bent 150 degrees geometry to one Na(2), one Ge(1), and one Si(3) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Na(2), one Ge(1), and one Si(2) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Na(2), one Ta(1), and one Si(3) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal bipyramidal geometry to one Na(1), one Na(2), one Na(3), one Ge(1), and one Si(1) atom. In the twelfth O site, O(12) is bonded in a rectangular see-saw-like geometry to one Na(1), one Na(2), one Ta(1), and one Si(1) atom.
Na3TaGeSi3O12 crystallizes in the monoclinic Cc space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(1), one O(11), one O(12), one O(2), one O(5), and one O(6) atom. The Na(1)-O(1) bond length is 2.30 Å. The Na(1)-O(11) bond length is 2.49 Å. The Na(1)-O(12) bond length is 2.41 Å. The Na(1)-O(2) bond length is 2.73 Å. The Na(1)-O(5) bond length is 2.39 Å. The Na(1)-O(6) bond length is 2.53 Å. In the second Na site, Na(2) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(11), one O(12), one O(2), one O(7), one O(8), and one O(9) atom. The Na(2)-O(1) bond length is 2.33 Å. The Na(2)-O(10) bond length is 2.59 Å. The Na(2)-O(11) bond length is 2.51 Å. The Na(2)-O(12) bond length is 2.44 Å. The Na(2)-O(2) bond length is 2.49 Å. The Na(2)-O(7) bond length is 2.96 Å. The Na(2)-O(8) bond length is 2.88 Å. The Na(2)-O(9) bond length is 2.49 Å. In the third Na site, Na(3) is bonded in a 7-coordinate geometry to one O(11), one O(2), one O(5), one O(6), one O(7), and two equivalent O(4) atoms. The Na(3)-O(11) bond length is 2.32 Å. The Na(3)-O(2) bond length is 2.46 Å. The Na(3)-O(5) bond length is 2.43 Å. The Na(3)-O(6) bond length is 2.44 Å. The Na(3)-O(7) bond length is 2.53 Å. There is one shorter (2.68 Å) and one longer (2.85 Å) Na(3)-O(4) bond length. Ta(1) is bonded to one O(10), one O(12), one O(2), one O(3), one O(6), and one O(7) atom to form TaO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. The Ta(1)-O(10) bond length is 1.96 Å. The Ta(1)-O(12) bond length is 2.01 Å. The Ta(1)-O(2) bond length is 2.05 Å. The Ta(1)-O(3) bond length is 1.91 Å. The Ta(1)-O(6) bond length is 2.02 Å. The Ta(1)-O(7) bond length is 1.96 Å. Ge(1) is bonded to one O(1), one O(11), one O(4), one O(5), one O(8), and one O(9) atom to form GeO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. The Ge(1)-O(1) bond length is 1.95 Å. The Ge(1)-O(11) bond length is 2.01 Å. The Ge(1)-O(4) bond length is 1.91 Å. The Ge(1)-O(5) bond length is 1.95 Å. The Ge(1)-O(8) bond length is 1.87 Å. The Ge(1)-O(9) bond length is 1.91 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(11), one O(12), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent Ta(1)O6 octahedra and corners with two equivalent Ge(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 20-40°. The Si(1)-O(11) bond length is 1.64 Å. The Si(1)-O(12) bond length is 1.65 Å. The Si(1)-O(3) bond length is 1.64 Å. The Si(1)-O(4) bond length is 1.64 Å. In the second Si site, Si(2) is bonded to one O(2), one O(5), one O(7), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Ta(1)O6 octahedra and corners with two equivalent Ge(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 26-36°. 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(7) bond length is 1.64 Å. The Si(2)-O(9) bond length is 1.63 Å. In the third Si site, Si(3) is bonded to one O(1), one O(10), one O(6), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Ta(1)O6 octahedra and corners with two equivalent Ge(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 22-36°. The Si(3)-O(1) bond length is 1.63 Å. The Si(3)-O(10) bond length is 1.65 Å. The Si(3)-O(6) bond length is 1.65 Å. The Si(3)-O(8) bond length is 1.63 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Na(1), one Na(2), one Ge(1), and one Si(3) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Na(3), one Ta(1), and one Si(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Ta(1) and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to two equivalent Na(3), one Ge(1), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(3), one Ge(1), and one Si(2) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(3), one Ta(1), and one Si(3) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one Na(2), one Na(3), one Ta(1), and one Si(2) atom. In the eighth O site, O(8) is bonded in a distorted bent 150 degrees geometry to one Na(2), one Ge(1), and one Si(3) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Na(2), one Ge(1), and one Si(2) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Na(2), one Ta(1), and one Si(3) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal bipyramidal geometry to one Na(1), one Na(2), one Na(3), one Ge(1), and one Si(1) atom. In the twelfth O site, O(12) is bonded in a rectangular see-saw-like geometry to one Na(1), one Na(2), one Ta(1), and one Si(1) atom.