MgCr2Fe3Ni(PO4)6 crystallizes in the trigonal R3 space group. Mg(1) is bonded in a 6-coordinate geometry to three equivalent O(3) and three equivalent O(8) atoms. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to three equivalent O(2) and three equivalent O(6) atoms to form distorted CrO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  a faceface with one Fe(1)O6 octahedra, and  a faceface with one Ni(1)O6 octahedra. In the second Cr site, Cr(2) is bonded to three equivalent O(4) and three equivalent O(7) atoms to form distorted CrO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  a faceface with one Fe(2)O6 octahedra, and  a faceface with one Fe(3)O6 octahedra. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent O(2) and three equivalent O(5) atoms to form distorted FeO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  a faceface with one Cr(1)O6 octahedra. In the second Fe site, Fe(2) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form distorted FeO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  a faceface with one Cr(2)O6 octahedra. In the third Fe site, Fe(3) is bonded to three equivalent O(7) and three equivalent O(8) atoms to form FeO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  a faceface with one Cr(2)O6 octahedra. Ni(1) is bonded to three equivalent O(3) and three equivalent O(6) atoms to form NiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  a faceface with one Cr(1)O6 octahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Cr(2)O6 octahedra,  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra, and  a cornercorner with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-54°. In the second P site, P(2) is bonded to one O(1), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Cr(2)O6 octahedra,  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra, and  a cornercorner with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 28-56°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Cr(1), one Fe(1), and one P(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1), one Ni(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Cr(2), one Fe(2), and one P(1) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Cr(1), one Ni(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Cr(2), one Fe(3), and one P(2) atom. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Mg(1), one Fe(3), and one P(1) atom.
MgCr2Fe3Ni(PO4)6 crystallizes in the trigonal R3 space group. Mg(1) is bonded in a 6-coordinate geometry to three equivalent O(3) and three equivalent O(8) atoms. All Mg(1)-O(3) bond lengths are 2.06 Å. All Mg(1)-O(8) bond lengths are 2.07 Å. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to three equivalent O(2) and three equivalent O(6) atoms to form distorted CrO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  a faceface with one Fe(1)O6 octahedra, and  a faceface with one Ni(1)O6 octahedra. All Cr(1)-O(2) bond lengths are 2.08 Å. All Cr(1)-O(6) bond lengths are 2.10 Å. In the second Cr site, Cr(2) is bonded to three equivalent O(4) and three equivalent O(7) atoms to form distorted CrO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  a faceface with one Fe(2)O6 octahedra, and  a faceface with one Fe(3)O6 octahedra. All Cr(2)-O(4) bond lengths are 2.08 Å. All Cr(2)-O(7) bond lengths are 2.11 Å. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent O(2) and three equivalent O(5) atoms to form distorted FeO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  a faceface with one Cr(1)O6 octahedra. All Fe(1)-O(2) bond lengths are 2.13 Å. All Fe(1)-O(5) bond lengths are 1.92 Å. In the second Fe site, Fe(2) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form distorted FeO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  a faceface with one Cr(2)O6 octahedra. All Fe(2)-O(1) bond lengths are 1.92 Å. All Fe(2)-O(4) bond lengths are 2.14 Å. In the third Fe site, Fe(3) is bonded to three equivalent O(7) and three equivalent O(8) atoms to form FeO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  a faceface with one Cr(2)O6 octahedra. All Fe(3)-O(7) bond lengths are 2.07 Å. All Fe(3)-O(8) bond lengths are 2.14 Å. Ni(1) is bonded to three equivalent O(3) and three equivalent O(6) atoms to form NiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  a faceface with one Cr(1)O6 octahedra. All Ni(1)-O(3) bond lengths are 2.12 Å. All Ni(1)-O(6) bond lengths are 2.02 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Cr(2)O6 octahedra,  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra, and  a cornercorner with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-54°. The P(1)-O(2) bond length is 1.57 Å. The P(1)-O(3) bond length is 1.54 Å. The P(1)-O(4) bond length is 1.57 Å. The P(1)-O(8) bond length is 1.54 Å. In the second P site, P(2) is bonded to one O(1), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Cr(2)O6 octahedra,  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra, and  a cornercorner with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 28-56°. The P(2)-O(1) bond length is 1.53 Å. The P(2)-O(5) bond length is 1.52 Å. The P(2)-O(6) bond length is 1.58 Å. The P(2)-O(7) bond length is 1.57 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(2) and one P(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Cr(1), one Fe(1), and one P(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1), one Ni(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Cr(2), one Fe(2), and one P(1) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Cr(1), one Ni(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Cr(2), one Fe(3), and one P(2) atom. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Mg(1), one Fe(3), and one P(1) atom.