CaNb2Ga2(CuO4)3 crystallizes in the monoclinic C2/m space group. Ca(1) is bonded to two equivalent O(1), two equivalent O(2), four equivalent O(3), and four equivalent O(4) atoms to form CaO12 cuboctahedra that share faces with four equivalent Nb(1)O6 octahedra and faces with four equivalent Ga(1)O6 octahedra. Nb(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Ga(1)O6 octahedra, and faces with two equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 41°. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a square co-planar geometry to four equivalent O(3) atoms. In the second Cu site, Cu(2) is bonded in a square co-planar geometry to four equivalent O(4) atoms. In the third Cu site, Cu(3) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. Ga(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form GaO6 octahedra that share corners with two equivalent Ga(1)O6 octahedra, corners with four equivalent Nb(1)O6 octahedra, and faces with two equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 41°. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Cu(3), and two equivalent Ga(1) atoms to form distorted OCaGa2Cu tetrahedra that share corners with two equivalent O(2)CaNb2Cu tetrahedra, corners with four equivalent O(1)CaGa2Cu tetrahedra, and  an edgeedge with one O(2)CaNb2Cu tetrahedra. In the second O site, O(2) is bonded to one Ca(1), two equivalent Nb(1), and one Cu(3) atom to form distorted OCaNb2Cu tetrahedra that share corners with two equivalent O(1)CaGa2Cu tetrahedra, corners with four equivalent O(2)CaNb2Cu tetrahedra, and  an edgeedge with one O(1)CaGa2Cu tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ca(1), one Nb(1), one Cu(1), and one Ga(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(1), one Nb(1), one Cu(2), and one Ga(1) atom.
CaNb2Ga2(CuO4)3 crystallizes in the monoclinic C2/m space group. Ca(1) is bonded to two equivalent O(1), two equivalent O(2), four equivalent O(3), and four equivalent O(4) atoms to form CaO12 cuboctahedra that share faces with four equivalent Nb(1)O6 octahedra and faces with four equivalent Ga(1)O6 octahedra. Both Ca(1)-O(1) bond lengths are 2.64 Å. Both Ca(1)-O(2) bond lengths are 2.66 Å. All Ca(1)-O(3) bond lengths are 2.66 Å. All Ca(1)-O(4) bond lengths are 2.66 Å. Nb(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Ga(1)O6 octahedra, and faces with two equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 41°. Both Nb(1)-O(2) bond lengths are 2.02 Å. Both Nb(1)-O(3) bond lengths are 2.01 Å. Both Nb(1)-O(4) bond lengths are 2.01 Å. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a square co-planar geometry to four equivalent O(3) atoms. All Cu(1)-O(3) bond lengths are 1.98 Å. In the second Cu site, Cu(2) is bonded in a square co-planar geometry to four equivalent O(4) atoms. All Cu(2)-O(4) bond lengths are 1.98 Å. In the third Cu site, Cu(3) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. Both Cu(3)-O(1) bond lengths are 1.98 Å. Both Cu(3)-O(2) bond lengths are 1.98 Å. Ga(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form GaO6 octahedra that share corners with two equivalent Ga(1)O6 octahedra, corners with four equivalent Nb(1)O6 octahedra, and faces with two equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 41°. Both Ga(1)-O(1) bond lengths are 2.02 Å. Both Ga(1)-O(3) bond lengths are 2.04 Å. Both Ga(1)-O(4) bond lengths are 2.03 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Cu(3), and two equivalent Ga(1) atoms to form distorted OCaGa2Cu tetrahedra that share corners with two equivalent O(2)CaNb2Cu tetrahedra, corners with four equivalent O(1)CaGa2Cu tetrahedra, and  an edgeedge with one O(2)CaNb2Cu tetrahedra. In the second O site, O(2) is bonded to one Ca(1), two equivalent Nb(1), and one Cu(3) atom to form distorted OCaNb2Cu tetrahedra that share corners with two equivalent O(1)CaGa2Cu tetrahedra, corners with four equivalent O(2)CaNb2Cu tetrahedra, and  an edgeedge with one O(1)CaGa2Cu tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ca(1), one Nb(1), one Cu(1), and one Ga(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(1), one Nb(1), one Cu(2), and one Ga(1) atom.