MgYbSe3 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form distorted edge-sharing MgSe6 pentagonal pyramids. Yb(1) is bonded in a 8-coordinate geometry to two equivalent Se(2) and six equivalent Se(1) atoms. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to two equivalent Mg(1) and three equivalent Yb(1) atoms. In the second Se site, Se(2) is bonded to two equivalent Mg(1) and two equivalent Yb(1) atoms to form distorted edge-sharing SeYb2Mg2 tetrahedra.
MgYbSe3 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form distorted edge-sharing MgSe6 pentagonal pyramids. Both Mg(1)-Se(2) bond lengths are 2.69 Å. There are two shorter (2.74 Å) and two longer (2.75 Å) Mg(1)-Se(1) bond lengths. Yb(1) is bonded in a 8-coordinate geometry to two equivalent Se(2) and six equivalent Se(1) atoms. There is one shorter (2.89 Å) and one longer (2.96 Å) Yb(1)-Se(2) bond length. There are a spread of Yb(1)-Se(1) bond distances ranging from 3.10-3.24 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to two equivalent Mg(1) and three equivalent Yb(1) atoms. In the second Se site, Se(2) is bonded to two equivalent Mg(1) and two equivalent Yb(1) atoms to form distorted edge-sharing SeYb2Mg2 tetrahedra.