Sc2GaN3 crystallizes in the monoclinic C2/c space group. There are two inequivalent Sc sites. In the first Sc site, Sc(1) is bonded to one N(1), one N(2), one N(4), and two equivalent N(3) atoms to form distorted ScN5 trigonal bipyramids that share corners with five equivalent Ga(1)N4 tetrahedra,  an edgeedge with one Ga(1)N4 tetrahedra, and edges with two equivalent Sc(1)N5 trigonal bipyramids. In the second Sc site, Sc(2) is bonded in a 6-coordinate geometry to one N(1), one N(4), two equivalent N(2), and two equivalent N(3) atoms. Ga(1) is bonded to one N(1), one N(2), one N(3), and one N(4) atom to form GaN4 tetrahedra that share corners with two equivalent Ga(1)N4 tetrahedra, corners with five equivalent Sc(1)N5 trigonal bipyramids, and  an edgeedge with one Sc(1)N5 trigonal bipyramid. There are four inequivalent N sites. In the first N site, N(4) is bonded in a 6-coordinate geometry to two equivalent Sc(1), two equivalent Sc(2), and two equivalent Ga(1) atoms. In the second N site, N(1) is bonded to two equivalent Sc(1), two equivalent Sc(2), and two equivalent Ga(1) atoms to form a mixture of distorted edge and corner-sharing NSc4Ga2 octahedra. In the third N site, N(2) is bonded in a distorted see-saw-like geometry to one Sc(1), two equivalent Sc(2), and one Ga(1) atom. In the fourth N site, N(3) is bonded to two equivalent Sc(1), two equivalent Sc(2), and one Ga(1) atom to form distorted NSc4Ga trigonal bipyramids that share corners with three equivalent N(1)Sc4Ga2 octahedra,  an edgeedge with one N(1)Sc4Ga2 octahedra, and edges with two equivalent N(3)Sc4Ga trigonal bipyramids. The corner-sharing octahedral tilt angles range from 32-65°.
Sc2GaN3 crystallizes in the monoclinic C2/c space group. There are two inequivalent Sc sites. In the first Sc site, Sc(1) is bonded to one N(1), one N(2), one N(4), and two equivalent N(3) atoms to form distorted ScN5 trigonal bipyramids that share corners with five equivalent Ga(1)N4 tetrahedra,  an edgeedge with one Ga(1)N4 tetrahedra, and edges with two equivalent Sc(1)N5 trigonal bipyramids. The Sc(1)-N(1) bond length is 2.29 Å. The Sc(1)-N(2) bond length is 2.18 Å. The Sc(1)-N(4) bond length is 2.35 Å. There is one shorter (2.07 Å) and one longer (2.23 Å) Sc(1)-N(3) bond length. In the second Sc site, Sc(2) is bonded in a 6-coordinate geometry to one N(1), one N(4), two equivalent N(2), and two equivalent N(3) atoms. The Sc(2)-N(1) bond length is 2.80 Å. The Sc(2)-N(4) bond length is 2.63 Å. There is one shorter (2.11 Å) and one longer (2.20 Å) Sc(2)-N(2) bond length. There is one shorter (2.15 Å) and one longer (2.38 Å) Sc(2)-N(3) bond length. Ga(1) is bonded to one N(1), one N(2), one N(3), and one N(4) atom to form GaN4 tetrahedra that share corners with two equivalent Ga(1)N4 tetrahedra, corners with five equivalent Sc(1)N5 trigonal bipyramids, and  an edgeedge with one Sc(1)N5 trigonal bipyramid. The Ga(1)-N(1) bond length is 1.94 Å. The Ga(1)-N(2) bond length is 1.92 Å. The Ga(1)-N(3) bond length is 1.95 Å. The Ga(1)-N(4) bond length is 1.94 Å. There are four inequivalent N sites. In the first N site, N(4) is bonded in a 6-coordinate geometry to two equivalent Sc(1), two equivalent Sc(2), and two equivalent Ga(1) atoms. In the second N site, N(1) is bonded to two equivalent Sc(1), two equivalent Sc(2), and two equivalent Ga(1) atoms to form a mixture of distorted edge and corner-sharing NSc4Ga2 octahedra. In the third N site, N(2) is bonded in a distorted see-saw-like geometry to one Sc(1), two equivalent Sc(2), and one Ga(1) atom. In the fourth N site, N(3) is bonded to two equivalent Sc(1), two equivalent Sc(2), and one Ga(1) atom to form distorted NSc4Ga trigonal bipyramids that share corners with three equivalent N(1)Sc4Ga2 octahedra,  an edgeedge with one N(1)Sc4Ga2 octahedra, and edges with two equivalent N(3)Sc4Ga trigonal bipyramids. The corner-sharing octahedral tilt angles range from 32-65°.