CrGaSe3 crystallizes in the orthorhombic Pnma space group. Cr(1) is bonded to one Se(2), two equivalent Se(3), and three equivalent Se(1) atoms to form CrSe6 octahedra that share corners with three equivalent Ga(1)Se4 tetrahedra, edges with four equivalent Cr(1)Se6 octahedra, and edges with two equivalent Ga(1)Se4 tetrahedra. Ga(1) is bonded to one Se(1), one Se(3), and two equivalent Se(2) atoms to form GaSe4 tetrahedra that share corners with three equivalent Cr(1)Se6 octahedra, corners with two equivalent Ga(1)Se4 tetrahedra, and edges with two equivalent Cr(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 59-60°. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to three equivalent Cr(1) and one Ga(1) atom to form a mixture of distorted corner and edge-sharing SeCr3Ga trigonal pyramids. In the second Se site, Se(2) is bonded in a 3-coordinate geometry to one Cr(1) and two equivalent Ga(1) atoms. In the third Se site, Se(3) is bonded in a distorted T-shaped geometry to two equivalent Cr(1) and one Ga(1) atom.
CrGaSe3 crystallizes in the orthorhombic Pnma space group. Cr(1) is bonded to one Se(2), two equivalent Se(3), and three equivalent Se(1) atoms to form CrSe6 octahedra that share corners with three equivalent Ga(1)Se4 tetrahedra, edges with four equivalent Cr(1)Se6 octahedra, and edges with two equivalent Ga(1)Se4 tetrahedra. The Cr(1)-Se(2) bond length is 2.60 Å. Both Cr(1)-Se(3) bond lengths are 2.56 Å. There are two shorter (2.57 Å) and one longer (2.58 Å) Cr(1)-Se(1) bond length. Ga(1) is bonded to one Se(1), one Se(3), and two equivalent Se(2) atoms to form GaSe4 tetrahedra that share corners with three equivalent Cr(1)Se6 octahedra, corners with two equivalent Ga(1)Se4 tetrahedra, and edges with two equivalent Cr(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 59-60°. The Ga(1)-Se(1) bond length is 2.42 Å. The Ga(1)-Se(3) bond length is 2.38 Å. Both Ga(1)-Se(2) bond lengths are 2.41 Å. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to three equivalent Cr(1) and one Ga(1) atom to form a mixture of distorted corner and edge-sharing SeCr3Ga trigonal pyramids. In the second Se site, Se(2) is bonded in a 3-coordinate geometry to one Cr(1) and two equivalent Ga(1) atoms. In the third Se site, Se(3) is bonded in a distorted T-shaped geometry to two equivalent Cr(1) and one Ga(1) atom.