Na2MgNb2O6 crystallizes in the trigonal R-3 space group. Na(1) is bonded to six equivalent O(1) atoms to form distorted NaO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with nine equivalent Nb(1)O6 octahedra, edges with three equivalent Na(1)O6 octahedra,  a faceface with one Mg(1)O6 octahedra, and  a faceface with one Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-53°. Mg(1) is bonded to six equivalent O(1) atoms to form MgO6 octahedra that share corners with six equivalent Na(1)O6 octahedra, edges with six equivalent Nb(1)O6 octahedra, and faces with two equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles are 45°. Nb(1) is bonded to six equivalent O(1) atoms to form NbO6 octahedra that share corners with nine equivalent Na(1)O6 octahedra, edges with three equivalent Mg(1)O6 octahedra, edges with three equivalent Nb(1)O6 octahedra, and  a faceface with one Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-53°. O(1) is bonded to two equivalent Na(1), one Mg(1), and two equivalent Nb(1) atoms to form a mixture of distorted corner and edge-sharing ONa2MgNb2 trigonal bipyramids.
Na2MgNb2O6 crystallizes in the trigonal R-3 space group. Na(1) is bonded to six equivalent O(1) atoms to form distorted NaO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with nine equivalent Nb(1)O6 octahedra, edges with three equivalent Na(1)O6 octahedra,  a faceface with one Mg(1)O6 octahedra, and  a faceface with one Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-53°. There are three shorter (2.46 Å) and three longer (2.48 Å) Na(1)-O(1) bond lengths. Mg(1) is bonded to six equivalent O(1) atoms to form MgO6 octahedra that share corners with six equivalent Na(1)O6 octahedra, edges with six equivalent Nb(1)O6 octahedra, and faces with two equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles are 45°. All Mg(1)-O(1) bond lengths are 2.09 Å. Nb(1) is bonded to six equivalent O(1) atoms to form NbO6 octahedra that share corners with nine equivalent Na(1)O6 octahedra, edges with three equivalent Mg(1)O6 octahedra, edges with three equivalent Nb(1)O6 octahedra, and  a faceface with one Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-53°. There are three shorter (2.05 Å) and three longer (2.19 Å) Nb(1)-O(1) bond lengths. O(1) is bonded to two equivalent Na(1), one Mg(1), and two equivalent Nb(1) atoms to form a mixture of distorted corner and edge-sharing ONa2MgNb2 trigonal bipyramids.