Na2GeO9 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1), one O(6), one O(9), and two equivalent O(8) atoms. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to one O(2), one O(4), and two equivalent O(3) atoms. Ge(1) is bonded in a distorted trigonal bipyramidal geometry to one O(1), one O(2), one O(3), one O(4), and one O(9) atom. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a water-like geometry to one Na(1) and one Ge(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Na(2), one Ge(1), and one O(5) atom. In the third O site, O(3) is bonded in a trigonal non-coplanar geometry to two equivalent Na(2) and one Ge(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(2), one Ge(1), and one O(9) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one O(2) and one O(8) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Na(1) and one O(7) atom. In the seventh O site, O(7) is bonded in a single-bond geometry to one O(6) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to two equivalent Na(1) and one O(5) atom. In the ninth O site, O(9) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Ge(1), and one O(4) atom.
Na2GeO9 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1), one O(6), one O(9), and two equivalent O(8) atoms. The Na(1)-O(1) bond length is 2.33 Å. The Na(1)-O(6) bond length is 2.68 Å. The Na(1)-O(9) bond length is 2.36 Å. There is one shorter (2.59 Å) and one longer (2.62 Å) Na(1)-O(8) bond length. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to one O(2), one O(4), and two equivalent O(3) atoms. The Na(2)-O(2) bond length is 2.47 Å. The Na(2)-O(4) bond length is 2.93 Å. There is one shorter (2.24 Å) and one longer (2.30 Å) Na(2)-O(3) bond length. Ge(1) is bonded in a distorted trigonal bipyramidal geometry to one O(1), one O(2), one O(3), one O(4), and one O(9) atom. The Ge(1)-O(1) bond length is 1.72 Å. The Ge(1)-O(2) bond length is 1.96 Å. The Ge(1)-O(3) bond length is 1.70 Å. The Ge(1)-O(4) bond length is 2.09 Å. The Ge(1)-O(9) bond length is 2.29 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a water-like geometry to one Na(1) and one Ge(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Na(2), one Ge(1), and one O(5) atom. The O(2)-O(5) bond length is 1.49 Å. In the third O site, O(3) is bonded in a trigonal non-coplanar geometry to two equivalent Na(2) and one Ge(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(2), one Ge(1), and one O(9) atom. The O(4)-O(9) bond length is 1.33 Å. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one O(2) and one O(8) atom. The O(5)-O(8) bond length is 1.32 Å. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Na(1) and one O(7) atom. The O(6)-O(7) bond length is 1.24 Å. In the seventh O site, O(7) is bonded in a single-bond geometry to one O(6) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to two equivalent Na(1) and one O(5) atom. In the ninth O site, O(9) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Ge(1), and one O(4) atom.