InAlS3 crystallizes in the hexagonal P6_1 space group. In(1) is bonded to one S(2), two equivalent S(1), and two equivalent S(3) atoms to form InS5 trigonal bipyramids that share corners with four equivalent Al(1)S4 tetrahedra,  an edgeedge with one Al(1)S4 tetrahedra, and edges with two equivalent In(1)S5 trigonal bipyramids. Al(1) is bonded to one S(1), one S(3), and two equivalent S(2) atoms to form AlS4 tetrahedra that share corners with two equivalent Al(1)S4 tetrahedra, corners with four equivalent In(1)S5 trigonal bipyramids, and  an edgeedge with one In(1)S5 trigonal bipyramid. There are three inequivalent S sites. In the first S site, S(1) is bonded in a distorted T-shaped geometry to two equivalent In(1) and one Al(1) atom. In the second S site, S(2) is bonded in a trigonal non-coplanar geometry to one In(1) and two equivalent Al(1) atoms. In the third S site, S(3) is bonded in a trigonal non-coplanar geometry to two equivalent In(1) and one Al(1) atom.
InAlS3 crystallizes in the hexagonal P6_1 space group. In(1) is bonded to one S(2), two equivalent S(1), and two equivalent S(3) atoms to form InS5 trigonal bipyramids that share corners with four equivalent Al(1)S4 tetrahedra,  an edgeedge with one Al(1)S4 tetrahedra, and edges with two equivalent In(1)S5 trigonal bipyramids. The In(1)-S(2) bond length is 2.55 Å. There is one shorter (2.50 Å) and one longer (2.70 Å) In(1)-S(1) bond length. There is one shorter (2.51 Å) and one longer (2.67 Å) In(1)-S(3) bond length. Al(1) is bonded to one S(1), one S(3), and two equivalent S(2) atoms to form AlS4 tetrahedra that share corners with two equivalent Al(1)S4 tetrahedra, corners with four equivalent In(1)S5 trigonal bipyramids, and  an edgeedge with one In(1)S5 trigonal bipyramid. The Al(1)-S(1) bond length is 2.24 Å. The Al(1)-S(3) bond length is 2.23 Å. There is one shorter (2.27 Å) and one longer (2.29 Å) Al(1)-S(2) bond length. There are three inequivalent S sites. In the first S site, S(1) is bonded in a distorted T-shaped geometry to two equivalent In(1) and one Al(1) atom. In the second S site, S(2) is bonded in a trigonal non-coplanar geometry to one In(1) and two equivalent Al(1) atoms. In the third S site, S(3) is bonded in a trigonal non-coplanar geometry to two equivalent In(1) and one Al(1) atom.