In3Se3As crystallizes in the monoclinic Cm space group. There are three inequivalent In sites. In the first In site, In(1) is bonded to one As(1), one Se(3), and two equivalent Se(2) atoms to form InAsSe3 tetrahedra that share corners with two equivalent In(1)AsSe3 tetrahedra, corners with three equivalent In(2)AsSe3 tetrahedra, and corners with four equivalent In(3)As2Se2 tetrahedra. In the second In site, In(2) is bonded to one As(1), one Se(1), and two equivalent Se(3) atoms to form InAsSe3 tetrahedra that share corners with two equivalent In(2)AsSe3 tetrahedra, corners with three equivalent In(3)As2Se2 tetrahedra, and corners with three equivalent In(1)AsSe3 tetrahedra. In the third In site, In(3) is bonded to two equivalent As(1), one Se(1), and one Se(2) atom to form InAs2Se2 tetrahedra that share corners with two equivalent In(3)As2Se2 tetrahedra, corners with three equivalent In(2)AsSe3 tetrahedra, and corners with four equivalent In(1)AsSe3 tetrahedra. As(1) is bonded to one In(1), one In(2), and two equivalent In(3) atoms to form corner-sharing AsIn4 tetrahedra. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a water-like geometry to one In(2) and one In(3) atom. In the second Se site, Se(2) is bonded in a trigonal non-coplanar geometry to one In(3) and two equivalent In(1) atoms. In the third Se site, Se(3) is bonded in a trigonal non-coplanar geometry to one In(1) and two equivalent In(2) atoms.
In3Se3As crystallizes in the monoclinic Cm space group. There are three inequivalent In sites. In the first In site, In(1) is bonded to one As(1), one Se(3), and two equivalent Se(2) atoms to form InAsSe3 tetrahedra that share corners with two equivalent In(1)AsSe3 tetrahedra, corners with three equivalent In(2)AsSe3 tetrahedra, and corners with four equivalent In(3)As2Se2 tetrahedra. The In(1)-As(1) bond length is 2.65 Å. The In(1)-Se(3) bond length is 2.65 Å. Both In(1)-Se(2) bond lengths are 2.67 Å. In the second In site, In(2) is bonded to one As(1), one Se(1), and two equivalent Se(3) atoms to form InAsSe3 tetrahedra that share corners with two equivalent In(2)AsSe3 tetrahedra, corners with three equivalent In(3)As2Se2 tetrahedra, and corners with three equivalent In(1)AsSe3 tetrahedra. The In(2)-As(1) bond length is 2.69 Å. The In(2)-Se(1) bond length is 2.55 Å. Both In(2)-Se(3) bond lengths are 2.71 Å. In the third In site, In(3) is bonded to two equivalent As(1), one Se(1), and one Se(2) atom to form InAs2Se2 tetrahedra that share corners with two equivalent In(3)As2Se2 tetrahedra, corners with three equivalent In(2)AsSe3 tetrahedra, and corners with four equivalent In(1)AsSe3 tetrahedra. Both In(3)-As(1) bond lengths are 2.66 Å. The In(3)-Se(1) bond length is 2.56 Å. The In(3)-Se(2) bond length is 2.70 Å. As(1) is bonded to one In(1), one In(2), and two equivalent In(3) atoms to form corner-sharing AsIn4 tetrahedra. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a water-like geometry to one In(2) and one In(3) atom. In the second Se site, Se(2) is bonded in a trigonal non-coplanar geometry to one In(3) and two equivalent In(1) atoms. In the third Se site, Se(3) is bonded in a trigonal non-coplanar geometry to one In(1) and two equivalent In(2) atoms.