MgNdSe3 is Ilmenite structured and crystallizes in the trigonal R-3 space group. Mg(1) is bonded to six equivalent Se(1) atoms to form MgSe6 octahedra that share corners with nine equivalent Nd(1)Se6 octahedra, edges with three equivalent Mg(1)Se6 octahedra, and  a faceface with one Nd(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 37-58°. Nd(1) is bonded to six equivalent Se(1) atoms to form distorted NdSe6 octahedra that share corners with nine equivalent Mg(1)Se6 octahedra, edges with three equivalent Nd(1)Se6 octahedra, and  a faceface with one Mg(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 37-58°. Se(1) is bonded in a distorted see-saw-like geometry to two equivalent Mg(1) and two equivalent Nd(1) atoms.
MgNdSe3 is Ilmenite structured and crystallizes in the trigonal R-3 space group. Mg(1) is bonded to six equivalent Se(1) atoms to form MgSe6 octahedra that share corners with nine equivalent Nd(1)Se6 octahedra, edges with three equivalent Mg(1)Se6 octahedra, and  a faceface with one Nd(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 37-58°. There are three shorter (2.72 Å) and three longer (2.77 Å) Mg(1)-Se(1) bond lengths. Nd(1) is bonded to six equivalent Se(1) atoms to form distorted NdSe6 octahedra that share corners with nine equivalent Mg(1)Se6 octahedra, edges with three equivalent Nd(1)Se6 octahedra, and  a faceface with one Mg(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 37-58°. There are three shorter (2.94 Å) and three longer (2.98 Å) Nd(1)-Se(1) bond lengths. Se(1) is bonded in a distorted see-saw-like geometry to two equivalent Mg(1) and two equivalent Nd(1) atoms.