MgCu2(SbO3)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(11), one O(2), one O(3), one O(5), one O(8), and one O(9) atom to form distorted MgO6 octahedra that share corners with two equivalent Sb(2)O6 octahedra, corners with two equivalent Sb(3)O6 octahedra, edges with two equivalent Sb(1)O6 octahedra, edges with two equivalent Sb(4)O6 octahedra, and faces with two equivalent Cu(2)O6 octahedra. The corner-sharing octahedral tilt angles are 48°. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(1), one O(10), one O(12), one O(4), one O(6), and one O(7) atom to form CuO6 octahedra that share corners with four equivalent Sb(2)O6 octahedra, corners with four equivalent Sb(3)O6 octahedra,  an edgeedge with one Sb(1)O6 octahedra, and  an edgeedge with one Sb(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-51°. In the second Cu site, Cu(2) is bonded to one O(11), one O(2), one O(3), one O(5), one O(8), and one O(9) atom to form distorted CuO6 octahedra that share corners with four equivalent Sb(1)O6 octahedra, corners with four equivalent Sb(4)O6 octahedra,  an edgeedge with one Sb(2)O6 octahedra,  an edgeedge with one Sb(3)O6 octahedra, and faces with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-53°. There are four inequivalent Sb sites. In the first Sb site, Sb(1) is bonded to one O(10), one O(11), one O(12), one O(2), one O(3), and one O(9) atom to form SbO6 octahedra that share corners with four equivalent Cu(2)O6 octahedra, corners with four equivalent Sb(3)O6 octahedra,  an edgeedge with one Cu(1)O6 octahedra,  an edgeedge with one Sb(4)O6 octahedra, and edges with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-53°. In the second Sb site, Sb(2) is bonded to one O(1), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form SbO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Cu(1)O6 octahedra, corners with four equivalent Sb(4)O6 octahedra,  an edgeedge with one Cu(2)O6 octahedra, and  an edgeedge with one Sb(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-52°. In the third Sb site, Sb(3) is bonded to one O(1), one O(10), one O(11), one O(12), one O(2), and one O(7) atom to form SbO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Cu(1)O6 octahedra, corners with four equivalent Sb(1)O6 octahedra,  an edgeedge with one Cu(2)O6 octahedra, and  an edgeedge with one Sb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-52°. In the fourth Sb site, Sb(4) is bonded to one O(3), one O(4), one O(5), one O(6), one O(8), and one O(9) atom to form SbO6 octahedra that share corners with four equivalent Cu(2)O6 octahedra, corners with four equivalent Sb(2)O6 octahedra,  an edgeedge with one Cu(1)O6 octahedra,  an edgeedge with one Sb(1)O6 octahedra, and edges with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-53°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Cu(1), one Sb(2), and one Sb(3) atom. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Cu(2), one Sb(1), and one Sb(3) atom. In the third O site, O(3) is bonded to one Mg(1), one Cu(2), one Sb(1), and one Sb(4) atom to form a mixture of distorted edge and corner-sharing OMgCuSb2 trigonal pyramids. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Cu(1), one Sb(2), and one Sb(4) atom. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Cu(2), one Sb(2), and one Sb(4) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Cu(1), one Sb(2), and one Sb(4) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Cu(1), one Sb(2), and one Sb(3) atom. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Cu(2), one Sb(2), and one Sb(4) atom. In the ninth O site, O(9) is bonded to one Mg(1), one Cu(2), one Sb(1), and one Sb(4) atom to form a mixture of distorted edge and corner-sharing OMgCuSb2 trigonal pyramids. In the tenth O site, O(10) is bonded in a distorted T-shaped geometry to one Cu(1), one Sb(1), and one Sb(3) atom. In the eleventh O site, O(11) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Cu(2), one Sb(1), and one Sb(3) atom. In the twelfth O site, O(12) is bonded in a distorted T-shaped geometry to one Cu(1), one Sb(1), and one Sb(3) atom.
MgCu2(SbO3)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(11), one O(2), one O(3), one O(5), one O(8), and one O(9) atom to form distorted MgO6 octahedra that share corners with two equivalent Sb(2)O6 octahedra, corners with two equivalent Sb(3)O6 octahedra, edges with two equivalent Sb(1)O6 octahedra, edges with two equivalent Sb(4)O6 octahedra, and faces with two equivalent Cu(2)O6 octahedra. The corner-sharing octahedral tilt angles are 48°. The Mg(1)-O(11) bond length is 2.18 Å. The Mg(1)-O(2) bond length is 2.19 Å. The Mg(1)-O(3) bond length is 1.95 Å. The Mg(1)-O(5) bond length is 2.19 Å. The Mg(1)-O(8) bond length is 2.16 Å. The Mg(1)-O(9) bond length is 1.95 Å. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(1), one O(10), one O(12), one O(4), one O(6), and one O(7) atom to form CuO6 octahedra that share corners with four equivalent Sb(2)O6 octahedra, corners with four equivalent Sb(3)O6 octahedra,  an edgeedge with one Sb(1)O6 octahedra, and  an edgeedge with one Sb(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-51°. The Cu(1)-O(1) bond length is 2.20 Å. The Cu(1)-O(10) bond length is 2.17 Å. The Cu(1)-O(12) bond length is 2.15 Å. The Cu(1)-O(4) bond length is 2.15 Å. The Cu(1)-O(6) bond length is 2.16 Å. The Cu(1)-O(7) bond length is 2.20 Å. In the second Cu site, Cu(2) is bonded to one O(11), one O(2), one O(3), one O(5), one O(8), and one O(9) atom to form distorted CuO6 octahedra that share corners with four equivalent Sb(1)O6 octahedra, corners with four equivalent Sb(4)O6 octahedra,  an edgeedge with one Sb(2)O6 octahedra,  an edgeedge with one Sb(3)O6 octahedra, and faces with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-53°. The Cu(2)-O(11) bond length is 2.15 Å. The Cu(2)-O(2) bond length is 2.12 Å. The Cu(2)-O(3) bond length is 2.21 Å. The Cu(2)-O(5) bond length is 2.12 Å. The Cu(2)-O(8) bond length is 2.15 Å. The Cu(2)-O(9) bond length is 2.23 Å. There are four inequivalent Sb sites. In the first Sb site, Sb(1) is bonded to one O(10), one O(11), one O(12), one O(2), one O(3), and one O(9) atom to form SbO6 octahedra that share corners with four equivalent Cu(2)O6 octahedra, corners with four equivalent Sb(3)O6 octahedra,  an edgeedge with one Cu(1)O6 octahedra,  an edgeedge with one Sb(4)O6 octahedra, and edges with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-53°. The Sb(1)-O(10) bond length is 1.99 Å. The Sb(1)-O(11) bond length is 2.09 Å. The Sb(1)-O(12) bond length is 1.99 Å. The Sb(1)-O(2) bond length is 2.08 Å. The Sb(1)-O(3) bond length is 2.10 Å. The Sb(1)-O(9) bond length is 2.10 Å. In the second Sb site, Sb(2) is bonded to one O(1), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form SbO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Cu(1)O6 octahedra, corners with four equivalent Sb(4)O6 octahedra,  an edgeedge with one Cu(2)O6 octahedra, and  an edgeedge with one Sb(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-52°. The Sb(2)-O(1) bond length is 2.04 Å. The Sb(2)-O(4) bond length is 2.07 Å. The Sb(2)-O(5) bond length is 2.13 Å. The Sb(2)-O(6) bond length is 2.06 Å. The Sb(2)-O(7) bond length is 2.05 Å. The Sb(2)-O(8) bond length is 2.12 Å. In the third Sb site, Sb(3) is bonded to one O(1), one O(10), one O(11), one O(12), one O(2), and one O(7) atom to form SbO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Cu(1)O6 octahedra, corners with four equivalent Sb(1)O6 octahedra,  an edgeedge with one Cu(2)O6 octahedra, and  an edgeedge with one Sb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-52°. The Sb(3)-O(1) bond length is 2.04 Å. The Sb(3)-O(10) bond length is 2.06 Å. The Sb(3)-O(11) bond length is 2.12 Å. The Sb(3)-O(12) bond length is 2.07 Å. The Sb(3)-O(2) bond length is 2.12 Å. The Sb(3)-O(7) bond length is 2.04 Å. In the fourth Sb site, Sb(4) is bonded to one O(3), one O(4), one O(5), one O(6), one O(8), and one O(9) atom to form SbO6 octahedra that share corners with four equivalent Cu(2)O6 octahedra, corners with four equivalent Sb(2)O6 octahedra,  an edgeedge with one Cu(1)O6 octahedra,  an edgeedge with one Sb(1)O6 octahedra, and edges with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-53°. The Sb(4)-O(3) bond length is 2.11 Å. The Sb(4)-O(4) bond length is 1.99 Å. The Sb(4)-O(5) bond length is 2.08 Å. The Sb(4)-O(6) bond length is 1.99 Å. The Sb(4)-O(8) bond length is 2.09 Å. The Sb(4)-O(9) bond length is 2.11 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Cu(1), one Sb(2), and one Sb(3) atom. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Cu(2), one Sb(1), and one Sb(3) atom. In the third O site, O(3) is bonded to one Mg(1), one Cu(2), one Sb(1), and one Sb(4) atom to form a mixture of distorted edge and corner-sharing OMgCuSb2 trigonal pyramids. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Cu(1), one Sb(2), and one Sb(4) atom. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Cu(2), one Sb(2), and one Sb(4) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Cu(1), one Sb(2), and one Sb(4) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Cu(1), one Sb(2), and one Sb(3) atom. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Cu(2), one Sb(2), and one Sb(4) atom. In the ninth O site, O(9) is bonded to one Mg(1), one Cu(2), one Sb(1), and one Sb(4) atom to form a mixture of distorted edge and corner-sharing OMgCuSb2 trigonal pyramids. In the tenth O site, O(10) is bonded in a distorted T-shaped geometry to one Cu(1), one Sb(1), and one Sb(3) atom. In the eleventh O site, O(11) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Cu(2), one Sb(1), and one Sb(3) atom. In the twelfth O site, O(12) is bonded in a distorted T-shaped geometry to one Cu(1), one Sb(1), and one Sb(3) atom.