MgCoP2O7 crystallizes in the monoclinic P2_1/c space group. Mg(1) is bonded to one O(2), one O(3), one O(5), one O(6), and one O(7) atom to form MgO5 trigonal bipyramids that share corners with two equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and edges with two equivalent Co(1)O6 octahedra. Co(1) is bonded to one O(3), one O(5), one O(6), one O(7), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one Co(1)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(4), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Co(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 49-54°. In the second P site, P(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Co(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with three equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 36-52°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Mg(1) and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Mg(1), one Co(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Co(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mg(1), one Co(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Mg(1), one Co(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Mg(1), one Co(1), and one P(1) atom.
MgCoP2O7 crystallizes in the monoclinic P2_1/c space group. Mg(1) is bonded to one O(2), one O(3), one O(5), one O(6), and one O(7) atom to form MgO5 trigonal bipyramids that share corners with two equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and edges with two equivalent Co(1)O6 octahedra. The Mg(1)-O(2) bond length is 1.98 Å. The Mg(1)-O(3) bond length is 2.09 Å. The Mg(1)-O(5) bond length is 2.03 Å. The Mg(1)-O(6) bond length is 2.08 Å. The Mg(1)-O(7) bond length is 2.06 Å. Co(1) is bonded to one O(3), one O(5), one O(6), one O(7), and two equivalent O(4) atoms to form CoO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one Co(1)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The Co(1)-O(3) bond length is 2.19 Å. The Co(1)-O(5) bond length is 2.23 Å. The Co(1)-O(6) bond length is 2.11 Å. The Co(1)-O(7) bond length is 2.10 Å. There is one shorter (2.07 Å) and one longer (2.18 Å) Co(1)-O(4) bond length. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(4), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Co(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 49-54°. The P(1)-O(1) bond length is 1.62 Å. The P(1)-O(2) bond length is 1.51 Å. The P(1)-O(4) bond length is 1.54 Å. The P(1)-O(7) bond length is 1.54 Å. In the second P site, P(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Co(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with three equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 36-52°. The P(2)-O(1) bond length is 1.60 Å. The P(2)-O(3) bond length is 1.54 Å. The P(2)-O(5) bond length is 1.53 Å. The P(2)-O(6) bond length is 1.54 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Mg(1) and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Mg(1), one Co(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Co(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mg(1), one Co(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Mg(1), one Co(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Mg(1), one Co(1), and one P(1) atom.