MgFe2CuAs2(HO5)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(10), one O(2), one O(3), one O(4), and one O(9) atom to form MgO6 octahedra that share corners with two equivalent As(1)O4 tetrahedra, corners with two equivalent As(2)O4 tetrahedra,  a cornercorner with one Fe(1)O5 trigonal bipyramid,  a cornercorner with one Fe(2)O5 trigonal bipyramid,  an edgeedge with one Fe(1)O5 trigonal bipyramid, and  an edgeedge with one Fe(2)O5 trigonal bipyramid. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(10), one O(5), one O(8), and one O(9) atom to form distorted FeO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one As(2)O4 tetrahedra, corners with two equivalent As(1)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra, and  an edgeedge with one Fe(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 56°. In the second Fe site, Fe(2) is bonded to one O(10), one O(2), one O(6), one O(7), and one O(9) atom to form distorted FeO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one As(1)O4 tetrahedra, corners with two equivalent As(2)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra, and  an edgeedge with one Fe(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 58°. Cu(1) is bonded in a square co-planar geometry to one O(10), one O(5), one O(6), and one O(9) atom. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form AsO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra,  a cornercorner with one Fe(2)O5 trigonal bipyramid, and corners with two equivalent Fe(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 55-57°. In the second As site, As(2) is bonded to one O(2), one O(4), one O(6), and one O(8) atom to form AsO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra,  a cornercorner with one Fe(1)O5 trigonal bipyramid, and corners with two equivalent Fe(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 54-59°. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(3) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(4) atom. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(1), and one As(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(2), and one As(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Mg(1), one As(1), and one H(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one As(2), and one H(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Fe(1), one Cu(1), and one As(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Fe(2), one Cu(1), and one As(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Fe(2) and one As(1) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Fe(1) and one As(2) atom. In the ninth O site, O(9) is bonded to one Mg(1), one Fe(1), one Fe(2), and one Cu(1) atom to form a mixture of corner and edge-sharing OMgFe2Cu trigonal pyramids. In the tenth O site, O(10) is bonded to one Mg(1), one Fe(1), one Fe(2), and one Cu(1) atom to form a mixture of corner and edge-sharing OMgFe2Cu trigonal pyramids.
MgFe2CuAs2(HO5)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(10), one O(2), one O(3), one O(4), and one O(9) atom to form MgO6 octahedra that share corners with two equivalent As(1)O4 tetrahedra, corners with two equivalent As(2)O4 tetrahedra,  a cornercorner with one Fe(1)O5 trigonal bipyramid,  a cornercorner with one Fe(2)O5 trigonal bipyramid,  an edgeedge with one Fe(1)O5 trigonal bipyramid, and  an edgeedge with one Fe(2)O5 trigonal bipyramid. The Mg(1)-O(1) bond length is 2.16 Å. The Mg(1)-O(10) bond length is 1.99 Å. The Mg(1)-O(2) bond length is 2.15 Å. The Mg(1)-O(3) bond length is 2.30 Å. The Mg(1)-O(4) bond length is 2.35 Å. The Mg(1)-O(9) bond length is 1.99 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(10), one O(5), one O(8), and one O(9) atom to form distorted FeO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one As(2)O4 tetrahedra, corners with two equivalent As(1)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra, and  an edgeedge with one Fe(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 56°. The Fe(1)-O(1) bond length is 2.26 Å. The Fe(1)-O(10) bond length is 2.03 Å. The Fe(1)-O(5) bond length is 2.19 Å. The Fe(1)-O(8) bond length is 2.03 Å. The Fe(1)-O(9) bond length is 2.08 Å. In the second Fe site, Fe(2) is bonded to one O(10), one O(2), one O(6), one O(7), and one O(9) atom to form distorted FeO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one As(1)O4 tetrahedra, corners with two equivalent As(2)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra, and  an edgeedge with one Fe(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 58°. The Fe(2)-O(10) bond length is 2.08 Å. The Fe(2)-O(2) bond length is 2.24 Å. The Fe(2)-O(6) bond length is 2.16 Å. The Fe(2)-O(7) bond length is 2.01 Å. The Fe(2)-O(9) bond length is 2.05 Å. Cu(1) is bonded in a square co-planar geometry to one O(10), one O(5), one O(6), and one O(9) atom. The Cu(1)-O(10) bond length is 1.91 Å. The Cu(1)-O(5) bond length is 2.03 Å. The Cu(1)-O(6) bond length is 2.03 Å. The Cu(1)-O(9) bond length is 1.91 Å. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form AsO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra,  a cornercorner with one Fe(2)O5 trigonal bipyramid, and corners with two equivalent Fe(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 55-57°. The As(1)-O(1) bond length is 1.70 Å. The As(1)-O(3) bond length is 1.82 Å. The As(1)-O(5) bond length is 1.72 Å. The As(1)-O(7) bond length is 1.69 Å. In the second As site, As(2) is bonded to one O(2), one O(4), one O(6), and one O(8) atom to form AsO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra,  a cornercorner with one Fe(1)O5 trigonal bipyramid, and corners with two equivalent Fe(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 54-59°. The As(2)-O(2) bond length is 1.70 Å. The As(2)-O(4) bond length is 1.83 Å. The As(2)-O(6) bond length is 1.71 Å. The As(2)-O(8) bond length is 1.70 Å. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(3) atom. The H(1)-O(3) bond length is 1.00 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(4) atom. The H(2)-O(4) bond length is 0.99 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(1), and one As(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mg(1), one Fe(2), and one As(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Mg(1), one As(1), and one H(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one As(2), and one H(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Fe(1), one Cu(1), and one As(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Fe(2), one Cu(1), and one As(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Fe(2) and one As(1) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Fe(1) and one As(2) atom. In the ninth O site, O(9) is bonded to one Mg(1), one Fe(1), one Fe(2), and one Cu(1) atom to form a mixture of corner and edge-sharing OMgFe2Cu trigonal pyramids. In the tenth O site, O(10) is bonded to one Mg(1), one Fe(1), one Fe(2), and one Cu(1) atom to form a mixture of corner and edge-sharing OMgFe2Cu trigonal pyramids.