Mg2Nb2FeO8 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 in a 6-coordinate geometry to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms. Fe(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form edge-sharing FeO6 octahedra. 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 Fe(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Nb(1) and two equivalent Fe(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 corner and edge-sharing OMg3Nb trigonal pyramids.
Mg2Nb2FeO8 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 2.05-2.42 Å. There are a spread of Mg(1)-O(4) bond distances ranging from 2.01-2.12 Å. Nb(1) is bonded in a 6-coordinate geometry to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms. The Nb(1)-O(2) bond length is 1.84 Å. The Nb(1)-O(4) bond length is 1.98 Å. There is one shorter (1.98 Å) and one longer (2.09 Å) Nb(1)-O(1) bond length. There is one shorter (2.05 Å) and one longer (2.44 Å) Nb(1)-O(3) bond length. Fe(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form edge-sharing FeO6 octahedra. Both Fe(1)-O(1) bond lengths are 2.15 Å. There are two shorter (2.16 Å) and two longer (2.19 Å) Fe(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 Fe(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Nb(1) and two equivalent Fe(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 corner and edge-sharing OMg3Nb trigonal pyramids.