Nb2Ge2O7 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), two equivalent O(1), and two equivalent O(6) atoms. In the second Nb site, Nb(2) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(7) atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles are 20°. There are two inequivalent Ge sites. In the first Ge site, Ge(1) is bonded in a distorted T-shaped geometry to one O(4) and two equivalent O(5) atoms. In the second Ge site, Ge(2) is bonded in a 4-coordinate geometry to one O(6), one O(7), and two equivalent O(3) atoms. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to two equivalent Nb(1) atoms. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Nb(1) and one Nb(2) atom. In the third O site, O(3) is bonded in a distorted see-saw-like geometry to one Nb(1), one Nb(2), and two equivalent Ge(2) atoms. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Nb(2) and one Ge(1) atom. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Nb(2) and two equivalent Ge(1) atoms. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Nb(1) and one Ge(2) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to two equivalent Nb(2) and one Ge(2) atom.
Nb2Ge2O7 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), two equivalent O(1), and two equivalent O(6) atoms. The Nb(1)-O(2) bond length is 1.85 Å. The Nb(1)-O(3) bond length is 2.22 Å. There is one shorter (1.84 Å) and one longer (2.40 Å) Nb(1)-O(1) bond length. Both Nb(1)-O(6) bond lengths are 2.05 Å. In the second Nb site, Nb(2) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(7) atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles are 20°. The Nb(2)-O(2) bond length is 2.18 Å. The Nb(2)-O(3) bond length is 2.11 Å. The Nb(2)-O(4) bond length is 1.97 Å. The Nb(2)-O(5) bond length is 1.91 Å. Both Nb(2)-O(7) bond lengths are 2.00 Å. There are two inequivalent Ge sites. In the first Ge site, Ge(1) is bonded in a distorted T-shaped geometry to one O(4) and two equivalent O(5) atoms. The Ge(1)-O(4) bond length is 1.88 Å. Both Ge(1)-O(5) bond lengths are 2.26 Å. In the second Ge site, Ge(2) is bonded in a 4-coordinate geometry to one O(6), one O(7), and two equivalent O(3) atoms. The Ge(2)-O(6) bond length is 2.01 Å. The Ge(2)-O(7) bond length is 2.31 Å. Both Ge(2)-O(3) bond lengths are 2.18 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to two equivalent Nb(1) atoms. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Nb(1) and one Nb(2) atom. In the third O site, O(3) is bonded in a distorted see-saw-like geometry to one Nb(1), one Nb(2), and two equivalent Ge(2) atoms. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Nb(2) and one Ge(1) atom. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Nb(2) and two equivalent Ge(1) atoms. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Nb(1) and one Ge(2) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to two equivalent Nb(2) and one Ge(2) atom.