CuGaS2 crystallizes in the trigonal R3m space group. Cu(1) is bonded to one Ga(1), one S(1), and three equivalent S(2) atoms to form distorted CuGaS4 tetrahedra that share corners with three equivalent S(1)Ga3Cu tetrahedra and corners with six equivalent Cu(1)GaS4 tetrahedra. Ga(1) is bonded in a 7-coordinate geometry to one Cu(1), three equivalent S(1), and three equivalent S(2) atoms. There are two inequivalent S sites. In the first S site, S(1) is bonded to one Cu(1) and three equivalent Ga(1) atoms to form SGa3Cu tetrahedra that share corners with three equivalent Cu(1)GaS4 tetrahedra and corners with six equivalent S(1)Ga3Cu tetrahedra. In the second S site, S(2) is bonded in a 6-coordinate geometry to three equivalent Cu(1) and three equivalent Ga(1) atoms.
CuGaS2 crystallizes in the trigonal R3m space group. Cu(1) is bonded to one Ga(1), one S(1), and three equivalent S(2) atoms to form distorted CuGaS4 tetrahedra that share corners with three equivalent S(1)Ga3Cu tetrahedra and corners with six equivalent Cu(1)GaS4 tetrahedra. The Cu(1)-Ga(1) bond length is 2.49 Å. The Cu(1)-S(1) bond length is 2.28 Å. All Cu(1)-S(2) bond lengths are 2.32 Å. Ga(1) is bonded in a 7-coordinate geometry to one Cu(1), three equivalent S(1), and three equivalent S(2) atoms. All Ga(1)-S(1) bond lengths are 2.43 Å. All Ga(1)-S(2) bond lengths are 2.70 Å. There are two inequivalent S sites. In the first S site, S(1) is bonded to one Cu(1) and three equivalent Ga(1) atoms to form SGa3Cu tetrahedra that share corners with three equivalent Cu(1)GaS4 tetrahedra and corners with six equivalent S(1)Ga3Cu tetrahedra. In the second S site, S(2) is bonded in a 6-coordinate geometry to three equivalent Cu(1) and three equivalent Ga(1) atoms.