Na2Mo2O7 crystallizes in the orthorhombic Cmce space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(3), two equivalent O(4), and two equivalent O(5) atoms to form distorted NaO6 pentagonal pyramids that share corners with three equivalent Mo(1)O4 tetrahedra and edges with two equivalent Na(2)O6 octahedra. In the second Na site, Na(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form NaO6 octahedra that share corners with four equivalent Mo(1)O4 tetrahedra, edges with two equivalent Na(2)O6 octahedra, and edges with two equivalent Na(1)O6 pentagonal pyramids. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one O(1), one O(2), and two equivalent O(5) atoms to form MoO4 tetrahedra that share corners with four equivalent Na(2)O6 octahedra and corners with three equivalent Na(1)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 51-60°. In the second Mo site, Mo(2) is bonded in a 6-coordinate geometry to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), two equivalent Na(2), and one Mo(1) atom to form distorted edge-sharing ONa3Mo trigonal pyramids. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Na(2) and one Mo(1) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Na(1) and two equivalent Mo(2) atoms. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), and one Mo(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Na(1), one Mo(1), and one Mo(2) atom.
Na2Mo2O7 crystallizes in the orthorhombic Cmce space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(3), two equivalent O(4), and two equivalent O(5) atoms to form distorted NaO6 pentagonal pyramids that share corners with three equivalent Mo(1)O4 tetrahedra and edges with two equivalent Na(2)O6 octahedra. The Na(1)-O(1) bond length is 2.35 Å. The Na(1)-O(3) bond length is 2.51 Å. Both Na(1)-O(4) bond lengths are 2.47 Å. Both Na(1)-O(5) bond lengths are 2.38 Å. In the second Na site, Na(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form NaO6 octahedra that share corners with four equivalent Mo(1)O4 tetrahedra, edges with two equivalent Na(2)O6 octahedra, and edges with two equivalent Na(1)O6 pentagonal pyramids. Both Na(2)-O(1) bond lengths are 2.41 Å. Both Na(2)-O(2) bond lengths are 2.36 Å. Both Na(2)-O(4) bond lengths are 2.40 Å. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one O(1), one O(2), and two equivalent O(5) atoms to form MoO4 tetrahedra that share corners with four equivalent Na(2)O6 octahedra and corners with three equivalent Na(1)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 51-60°. The Mo(1)-O(1) bond length is 1.76 Å. The Mo(1)-O(2) bond length is 1.74 Å. Both Mo(1)-O(5) bond lengths are 1.79 Å. In the second Mo site, Mo(2) is bonded in a 6-coordinate geometry to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms. Both Mo(2)-O(3) bond lengths are 1.91 Å. Both Mo(2)-O(4) bond lengths are 1.72 Å. Both Mo(2)-O(5) bond lengths are 2.29 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), two equivalent Na(2), and one Mo(1) atom to form distorted edge-sharing ONa3Mo trigonal pyramids. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Na(2) and one Mo(1) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Na(1) and two equivalent Mo(2) atoms. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), and one Mo(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Na(1), one Mo(1), and one Mo(2) atom.