Mn2SnSe4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form MnSe6 octahedra that share corners with four equivalent Mn(2)Se6 octahedra, corners with two equivalent Sn(1)Se4 tetrahedra, edges with two equivalent Mn(1)Se6 octahedra, edges with two equivalent Mn(2)Se6 octahedra, and edges with two equivalent Sn(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-53°. In the second Mn site, Mn(2) is bonded to one Se(2), one Se(3), and four equivalent Se(1) atoms to form MnSe6 octahedra that share corners with four equivalent Mn(1)Se6 octahedra, corners with four equivalent Mn(2)Se6 octahedra, corners with four equivalent Sn(1)Se4 tetrahedra, edges with two equivalent Mn(1)Se6 octahedra, and  an edgeedge with one Sn(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-53°. Sn(1) is bonded to one Se(2), one Se(3), and two equivalent Se(1) atoms to form SnSe4 tetrahedra that share corners with two equivalent Mn(1)Se6 octahedra, corners with four equivalent Mn(2)Se6 octahedra,  an edgeedge with one Mn(2)Se6 octahedra, and edges with two equivalent Mn(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 62-68°. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a rectangular see-saw-like geometry to one Mn(1), two equivalent Mn(2), and one Sn(1) atom. In the second Se site, Se(2) is bonded to one Mn(2), two equivalent Mn(1), and one Sn(1) atom to form corner-sharing SeMn3Sn tetrahedra. In the third Se site, Se(3) is bonded in a rectangular see-saw-like geometry to one Mn(2), two equivalent Mn(1), and one Sn(1) atom.
Mn2SnSe4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form MnSe6 octahedra that share corners with four equivalent Mn(2)Se6 octahedra, corners with two equivalent Sn(1)Se4 tetrahedra, edges with two equivalent Mn(1)Se6 octahedra, edges with two equivalent Mn(2)Se6 octahedra, and edges with two equivalent Sn(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-53°. Both Mn(1)-Se(1) bond lengths are 2.78 Å. Both Mn(1)-Se(2) bond lengths are 2.64 Å. Both Mn(1)-Se(3) bond lengths are 2.77 Å. In the second Mn site, Mn(2) is bonded to one Se(2), one Se(3), and four equivalent Se(1) atoms to form MnSe6 octahedra that share corners with four equivalent Mn(1)Se6 octahedra, corners with four equivalent Mn(2)Se6 octahedra, corners with four equivalent Sn(1)Se4 tetrahedra, edges with two equivalent Mn(1)Se6 octahedra, and  an edgeedge with one Sn(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-53°. The Mn(2)-Se(2) bond length is 2.67 Å. The Mn(2)-Se(3) bond length is 2.66 Å. There are two shorter (2.76 Å) and two longer (2.85 Å) Mn(2)-Se(1) bond lengths. Sn(1) is bonded to one Se(2), one Se(3), and two equivalent Se(1) atoms to form SnSe4 tetrahedra that share corners with two equivalent Mn(1)Se6 octahedra, corners with four equivalent Mn(2)Se6 octahedra,  an edgeedge with one Mn(2)Se6 octahedra, and edges with two equivalent Mn(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 62-68°. The Sn(1)-Se(2) bond length is 2.58 Å. The Sn(1)-Se(3) bond length is 2.59 Å. Both Sn(1)-Se(1) bond lengths are 2.58 Å. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a rectangular see-saw-like geometry to one Mn(1), two equivalent Mn(2), and one Sn(1) atom. In the second Se site, Se(2) is bonded to one Mn(2), two equivalent Mn(1), and one Sn(1) atom to form corner-sharing SeMn3Sn tetrahedra. In the third Se site, Se(3) is bonded in a rectangular see-saw-like geometry to one Mn(2), two equivalent Mn(1), and one Sn(1) atom.