Nb2Ge2O7 crystallizes in the monoclinic P2_1 space group. There are four inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(11), one O(2), one O(3), one O(5), and one O(7) atom to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 21-30°. In the second Nb site, Nb(2) is bonded in a 6-coordinate geometry to one O(10), one O(2), one O(4), one O(7), and two equivalent O(6) atoms. In the third Nb site, Nb(3) is bonded to one O(11), one O(12), one O(14), one O(3), one O(8), and one O(9) atom to form distorted corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 21-31°. In the fourth Nb site, Nb(4) is bonded to one O(10), one O(14), one O(4), one O(9), and two equivalent O(13) atoms to form distorted corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 5-31°. There are four inequivalent Ge sites. In the first Ge site, Ge(1) is bonded in a distorted T-shaped geometry to one O(1), one O(5), and one O(8) atom. In the second Ge site, Ge(2) is bonded in a 3-coordinate geometry to one O(2), one O(4), and one O(6) atom. In the third Ge site, Ge(3) is bonded in a 3-coordinate geometry to one O(10), one O(11), and one O(9) atom. In the fourth Ge site, Ge(4) is bonded in a distorted trigonal non-coplanar geometry to one O(8) and two equivalent O(12) atoms. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Nb(1) and one Ge(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Nb(1), one Nb(2), and one Ge(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Nb(1) and one Nb(3) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Nb(2), one Nb(4), and one Ge(2) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Nb(1) and one Ge(1) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to two equivalent Nb(2) and one Ge(2) atom. In the seventh O site, O(7) is bonded in a linear geometry to one Nb(1) and one Nb(2) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Nb(3), one Ge(1), and one Ge(4) atom. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one Nb(3), one Nb(4), and one Ge(3) atom. In the tenth O site, O(10) is bonded in a distorted trigonal non-coplanar geometry to one Nb(2), one Nb(4), and one Ge(3) atom. In the eleventh O site, O(11) is bonded in a distorted T-shaped geometry to one Nb(1), one Nb(3), and one Ge(3) atom. In the twelfth O site, O(12) is bonded in a trigonal planar geometry to one Nb(3) and two equivalent Ge(4) atoms. In the thirteenth O site, O(13) is bonded in a linear geometry to two equivalent Nb(4) atoms. In the fourteenth O site, O(14) is bonded in a bent 150 degrees geometry to one Nb(3) and one Nb(4) atom.
Nb2Ge2O7 crystallizes in the monoclinic P2_1 space group. There are four inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(11), one O(2), one O(3), one O(5), and one O(7) atom to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 21-30°. The Nb(1)-O(1) bond length is 1.88 Å. The Nb(1)-O(11) bond length is 1.97 Å. The Nb(1)-O(2) bond length is 2.21 Å. The Nb(1)-O(3) bond length is 2.12 Å. The Nb(1)-O(5) bond length is 1.89 Å. The Nb(1)-O(7) bond length is 2.13 Å. In the second Nb site, Nb(2) is bonded in a 6-coordinate geometry to one O(10), one O(2), one O(4), one O(7), and two equivalent O(6) atoms. The Nb(2)-O(10) bond length is 2.03 Å. The Nb(2)-O(2) bond length is 2.08 Å. The Nb(2)-O(4) bond length is 2.11 Å. The Nb(2)-O(7) bond length is 1.83 Å. There is one shorter (1.91 Å) and one longer (2.45 Å) Nb(2)-O(6) bond length. In the third Nb site, Nb(3) is bonded to one O(11), one O(12), one O(14), one O(3), one O(8), and one O(9) atom to form distorted corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 21-31°. The Nb(3)-O(11) bond length is 2.29 Å. The Nb(3)-O(12) bond length is 2.03 Å. The Nb(3)-O(14) bond length is 2.11 Å. The Nb(3)-O(3) bond length is 1.84 Å. The Nb(3)-O(8) bond length is 1.99 Å. The Nb(3)-O(9) bond length is 2.05 Å. In the fourth Nb site, Nb(4) is bonded to one O(10), one O(14), one O(4), one O(9), and two equivalent O(13) atoms to form distorted corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 5-31°. The Nb(4)-O(10) bond length is 2.09 Å. The Nb(4)-O(14) bond length is 1.89 Å. The Nb(4)-O(4) bond length is 2.02 Å. The Nb(4)-O(9) bond length is 2.23 Å. There is one shorter (1.84 Å) and one longer (2.33 Å) Nb(4)-O(13) bond length. There are four inequivalent Ge sites. In the first Ge site, Ge(1) is bonded in a distorted T-shaped geometry to one O(1), one O(5), and one O(8) atom. The Ge(1)-O(1) bond length is 1.89 Å. The Ge(1)-O(5) bond length is 1.94 Å. The Ge(1)-O(8) bond length is 2.21 Å. In the second Ge site, Ge(2) is bonded in a 3-coordinate geometry to one O(2), one O(4), and one O(6) atom. The Ge(2)-O(2) bond length is 1.95 Å. The Ge(2)-O(4) bond length is 2.07 Å. The Ge(2)-O(6) bond length is 2.11 Å. In the third Ge site, Ge(3) is bonded in a 3-coordinate geometry to one O(10), one O(11), and one O(9) atom. The Ge(3)-O(10) bond length is 2.05 Å. The Ge(3)-O(11) bond length is 2.05 Å. The Ge(3)-O(9) bond length is 2.01 Å. In the fourth Ge site, Ge(4) is bonded in a distorted trigonal non-coplanar geometry to one O(8) and two equivalent O(12) atoms. The Ge(4)-O(8) bond length is 2.01 Å. There is one shorter (2.04 Å) and one longer (2.21 Å) Ge(4)-O(12) bond length. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Nb(1) and one Ge(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Nb(1), one Nb(2), and one Ge(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Nb(1) and one Nb(3) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Nb(2), one Nb(4), and one Ge(2) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Nb(1) and one Ge(1) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to two equivalent Nb(2) and one Ge(2) atom. In the seventh O site, O(7) is bonded in a linear geometry to one Nb(1) and one Nb(2) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Nb(3), one Ge(1), and one Ge(4) atom. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one Nb(3), one Nb(4), and one Ge(3) atom. In the tenth O site, O(10) is bonded in a distorted trigonal non-coplanar geometry to one Nb(2), one Nb(4), and one Ge(3) atom. In the eleventh O site, O(11) is bonded in a distorted T-shaped geometry to one Nb(1), one Nb(3), and one Ge(3) atom. In the twelfth O site, O(12) is bonded in a trigonal planar geometry to one Nb(3) and two equivalent Ge(4) atoms. In the thirteenth O site, O(13) is bonded in a linear geometry to two equivalent Nb(4) atoms. In the fourteenth O site, O(14) is bonded in a bent 150 degrees geometry to one Nb(3) and one Nb(4) atom.