MgLaNb2CuO7Cl crystallizes in the orthorhombic Pmm2 space group. Mg(1) is bonded to one O(3), two equivalent O(2), and two equivalent Cl(1) atoms to form distorted MgCl2O3 trigonal bipyramids that share corners with two equivalent La(1)O12 cuboctahedra, corners with four equivalent Mg(1)Cl2O3 trigonal bipyramids, and edges with two equivalent Nb(1)O6 octahedra. La(1) is bonded to two equivalent O(1), two equivalent O(3), two equivalent O(5), two equivalent O(6), and four equivalent O(7) atoms to form distorted LaO12 cuboctahedra that share corners with four equivalent La(1)O12 cuboctahedra, corners with two equivalent Mg(1)Cl2O3 trigonal bipyramids, faces with four equivalent La(1)O12 cuboctahedra, and faces with four equivalent Nb(1)O6 octahedra. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(2), one O(7), two equivalent O(3), and two equivalent O(6) atoms to form NbO6 octahedra that share corners with four equivalent Nb(1)O6 octahedra, edges with two equivalent Mg(1)Cl2O3 trigonal bipyramids, and faces with four equivalent La(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 6-18°. In the second Nb site, Nb(2) is bonded in a 6-coordinate geometry to one O(4), one O(7), two equivalent O(1), and two equivalent O(5) atoms. Cu(1) is bonded in a distorted linear geometry to one O(2), one O(4), and four equivalent Cl(1) atoms. There are seven inequivalent O sites. In the first O site, O(1) is bonded to two equivalent La(1) and two equivalent Nb(2) atoms to form distorted corner-sharing OLa2Nb2 trigonal pyramids. In the second O site, O(2) is bonded in a square co-planar geometry to two equivalent Mg(1), one Nb(1), and one Cu(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1), two equivalent La(1), and two equivalent Nb(1) atoms. In the fourth O site, O(4) is bonded in a linear geometry to one Nb(2) and one Cu(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent La(1) and two equivalent Nb(2) atoms. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to two equivalent La(1) and two equivalent Nb(1) atoms. In the seventh O site, O(7) is bonded in a distorted linear geometry to four equivalent La(1), one Nb(1), and one Nb(2) atom. Cl(1) is bonded in a 6-coordinate geometry to two equivalent Mg(1) and four equivalent Cu(1) atoms.
MgLaNb2CuO7Cl crystallizes in the orthorhombic Pmm2 space group. Mg(1) is bonded to one O(3), two equivalent O(2), and two equivalent Cl(1) atoms to form distorted MgCl2O3 trigonal bipyramids that share corners with two equivalent La(1)O12 cuboctahedra, corners with four equivalent Mg(1)Cl2O3 trigonal bipyramids, and edges with two equivalent Nb(1)O6 octahedra. The Mg(1)-O(3) bond length is 2.10 Å. Both Mg(1)-O(2) bond lengths are 2.05 Å. Both Mg(1)-Cl(1) bond lengths are 2.46 Å. La(1) is bonded to two equivalent O(1), two equivalent O(3), two equivalent O(5), two equivalent O(6), and four equivalent O(7) atoms to form distorted LaO12 cuboctahedra that share corners with four equivalent La(1)O12 cuboctahedra, corners with two equivalent Mg(1)Cl2O3 trigonal bipyramids, faces with four equivalent La(1)O12 cuboctahedra, and faces with four equivalent Nb(1)O6 octahedra. Both La(1)-O(1) bond lengths are 2.56 Å. Both La(1)-O(3) bond lengths are 3.05 Å. Both La(1)-O(5) bond lengths are 2.59 Å. Both La(1)-O(6) bond lengths are 2.75 Å. All La(1)-O(7) bond lengths are 2.87 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(2), one O(7), two equivalent O(3), and two equivalent O(6) atoms to form NbO6 octahedra that share corners with four equivalent Nb(1)O6 octahedra, edges with two equivalent Mg(1)Cl2O3 trigonal bipyramids, and faces with four equivalent La(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 6-18°. The Nb(1)-O(2) bond length is 2.03 Å. The Nb(1)-O(7) bond length is 2.00 Å. Both Nb(1)-O(3) bond lengths are 2.04 Å. Both Nb(1)-O(6) bond lengths are 2.04 Å. In the second Nb site, Nb(2) is bonded in a 6-coordinate geometry to one O(4), one O(7), two equivalent O(1), and two equivalent O(5) atoms. The Nb(2)-O(4) bond length is 1.80 Å. The Nb(2)-O(7) bond length is 2.25 Å. Both Nb(2)-O(1) bond lengths are 2.10 Å. Both Nb(2)-O(5) bond lengths are 2.07 Å. Cu(1) is bonded in a distorted linear geometry to one O(2), one O(4), and four equivalent Cl(1) atoms. The Cu(1)-O(2) bond length is 1.96 Å. The Cu(1)-O(4) bond length is 1.83 Å. All Cu(1)-Cl(1) bond lengths are 2.89 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded to two equivalent La(1) and two equivalent Nb(2) atoms to form distorted corner-sharing OLa2Nb2 trigonal pyramids. In the second O site, O(2) is bonded in a square co-planar geometry to two equivalent Mg(1), one Nb(1), and one Cu(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1), two equivalent La(1), and two equivalent Nb(1) atoms. In the fourth O site, O(4) is bonded in a linear geometry to one Nb(2) and one Cu(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent La(1) and two equivalent Nb(2) atoms. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to two equivalent La(1) and two equivalent Nb(1) atoms. In the seventh O site, O(7) is bonded in a distorted linear geometry to four equivalent La(1), one Nb(1), and one Nb(2) atom. Cl(1) is bonded in a 6-coordinate geometry to two equivalent Mg(1) and four equivalent Cu(1) atoms.