MgNb2(O2F)2 crystallizes in the monoclinic C2 space group. Mg(1) is bonded in a 5-coordinate geometry to two equivalent O(1), two equivalent O(2), and one F(1) atom. Nb(1) is bonded to two equivalent O(1), two equivalent O(2), one F(1), and one F(2) atom to form corner-sharing NbO4F2 octahedra. The corner-sharing octahedral tilt angles range from 33-49°. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1) and two equivalent Nb(1) atoms. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Mg(1) and two equivalent Nb(1) atoms. There are two inequivalent F sites. In the first F site, F(1) is bonded in a trigonal planar geometry to one Mg(1) and two equivalent Nb(1) atoms. In the second F site, F(2) is bonded in a bent 120 degrees geometry to two equivalent Nb(1) atoms.
MgNb2(O2F)2 crystallizes in the monoclinic C2 space group. Mg(1) is bonded in a 5-coordinate geometry to two equivalent O(1), two equivalent O(2), and one F(1) atom. Both Mg(1)-O(1) bond lengths are 2.04 Å. Both Mg(1)-O(2) bond lengths are 2.10 Å. The Mg(1)-F(1) bond length is 2.03 Å. Nb(1) is bonded to two equivalent O(1), two equivalent O(2), one F(1), and one F(2) atom to form corner-sharing NbO4F2 octahedra. The corner-sharing octahedral tilt angles range from 33-49°. There is one shorter (1.98 Å) and one longer (2.10 Å) Nb(1)-O(1) bond length. There is one shorter (1.92 Å) and one longer (2.13 Å) Nb(1)-O(2) bond length. The Nb(1)-F(1) bond length is 2.29 Å. The Nb(1)-F(2) bond length is 2.11 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1) and two equivalent Nb(1) atoms. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Mg(1) and two equivalent Nb(1) atoms. There are two inequivalent F sites. In the first F site, F(1) is bonded in a trigonal planar geometry to one Mg(1) and two equivalent Nb(1) atoms. In the second F site, F(2) is bonded in a bent 120 degrees geometry to two equivalent Nb(1) atoms.