Mg2Nb2MoO8 crystallizes in the monoclinic C2/c space group. Mg(1) is bonded in a 6-coordinate geometry to three equivalent O(3) and three equivalent O(4) atoms. Nb(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form distorted NbO6 octahedra that share corners with four equivalent Mo(1)O6 octahedra and edges with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-54°. Mo(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form MoO6 octahedra that share corners with eight equivalent Nb(1)O6 octahedra and edges with two equivalent Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-54°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to two equivalent Nb(1) and one Mo(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Nb(1) and two equivalent Mo(1) atoms. In the third O site, O(3) is bonded in a 5-coordinate geometry to three equivalent Mg(1) and two equivalent Nb(1) atoms. In the fourth O site, O(4) is bonded to three equivalent Mg(1) and one Nb(1) atom to form a mixture of edge and corner-sharing OMg3Nb trigonal pyramids.
Mg2Nb2MoO8 crystallizes in the monoclinic C2/c space group. Mg(1) is bonded in a 6-coordinate geometry to three equivalent O(3) and three equivalent O(4) atoms. There are a spread of Mg(1)-O(3) bond distances ranging from 2.01-2.52 Å. There are a spread of Mg(1)-O(4) bond distances ranging from 2.02-2.07 Å. Nb(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form distorted NbO6 octahedra that share corners with four equivalent Mo(1)O6 octahedra and edges with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-54°. The Nb(1)-O(2) bond length is 1.94 Å. The Nb(1)-O(4) bond length is 1.99 Å. There is one shorter (2.03 Å) and one longer (2.10 Å) Nb(1)-O(1) bond length. There is one shorter (2.08 Å) and one longer (2.30 Å) Nb(1)-O(3) bond length. Mo(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form MoO6 octahedra that share corners with eight equivalent Nb(1)O6 octahedra and edges with two equivalent Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-54°. Both Mo(1)-O(1) bond lengths are 2.17 Å. There are two shorter (2.16 Å) and two longer (2.18 Å) Mo(1)-O(2) bond lengths. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to two equivalent Nb(1) and one Mo(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Nb(1) and two equivalent Mo(1) atoms. In the third O site, O(3) is bonded in a 5-coordinate geometry to three equivalent Mg(1) and two equivalent Nb(1) atoms. In the fourth O site, O(4) is bonded to three equivalent Mg(1) and one Nb(1) atom to form a mixture of edge and corner-sharing OMg3Nb trigonal pyramids.