Cr5(PO4)4 crystallizes in the triclinic P-1 space group. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(6) atoms to form distorted CrO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with four equivalent P(2)O4 tetrahedra, and edges with two equivalent Cr(2)O6 octahedra. In the second Cr site, Cr(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(7) atom to form CrO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one Cr(1)O6 octahedra,  an edgeedge with one P(1)O4 tetrahedra, and edges with two equivalent Cr(3)O5 trigonal bipyramids. In the third Cr site, Cr(3) is bonded to one O(2), one O(3), one O(5), one O(7), and one O(8) atom to form distorted CrO5 trigonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and edges with two equivalent Cr(2)O6 octahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(3), one O(4), one O(5), 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, corners with three equivalent Cr(3)O5 trigonal bipyramids, and  an edgeedge with one Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-59°. In the second P site, P(2) is bonded to one O(1), one O(2), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with three equivalent Cr(2)O6 octahedra, and corners with two equivalent Cr(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 44-49°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Cr(1), one Cr(2), and one P(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Cr(2), one Cr(3), and one P(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Cr(2), one Cr(3), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(2), and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Cr(2), one Cr(3), and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Cr(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Cr(2), one Cr(3), and one P(2) atom. In the eighth O site, O(8) is bonded in a distorted linear geometry to one Cr(3) and one P(1) atom.
Cr5(PO4)4 crystallizes in the triclinic P-1 space group. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(6) atoms to form distorted CrO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with four equivalent P(2)O4 tetrahedra, and edges with two equivalent Cr(2)O6 octahedra. Both Cr(1)-O(1) bond lengths are 2.56 Å. Both Cr(1)-O(4) bond lengths are 2.20 Å. Both Cr(1)-O(6) bond lengths are 2.02 Å. In the second Cr site, Cr(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(7) atom to form CrO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one Cr(1)O6 octahedra,  an edgeedge with one P(1)O4 tetrahedra, and edges with two equivalent Cr(3)O5 trigonal bipyramids. The Cr(2)-O(1) bond length is 2.00 Å. The Cr(2)-O(2) bond length is 2.02 Å. The Cr(2)-O(3) bond length is 2.04 Å. The Cr(2)-O(4) bond length is 2.05 Å. The Cr(2)-O(5) bond length is 2.07 Å. The Cr(2)-O(7) bond length is 2.05 Å. In the third Cr site, Cr(3) is bonded to one O(2), one O(3), one O(5), one O(7), and one O(8) atom to form distorted CrO5 trigonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and edges with two equivalent Cr(2)O6 octahedra. The Cr(3)-O(2) bond length is 2.29 Å. The Cr(3)-O(3) bond length is 2.18 Å. The Cr(3)-O(5) bond length is 2.07 Å. The Cr(3)-O(7) bond length is 2.09 Å. The Cr(3)-O(8) bond length is 2.06 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(3), one O(4), one O(5), 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, corners with three equivalent Cr(3)O5 trigonal bipyramids, and  an edgeedge with one Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-59°. The P(1)-O(3) bond length is 1.59 Å. The P(1)-O(4) bond length is 1.55 Å. The P(1)-O(5) bond length is 1.58 Å. The P(1)-O(8) bond length is 1.51 Å. In the second P site, P(2) is bonded to one O(1), one O(2), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with three equivalent Cr(2)O6 octahedra, and corners with two equivalent Cr(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 44-49°. The P(2)-O(1) bond length is 1.56 Å. The P(2)-O(2) bond length is 1.57 Å. The P(2)-O(6) bond length is 1.51 Å. The P(2)-O(7) bond length is 1.59 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Cr(1), one Cr(2), and one P(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Cr(2), one Cr(3), and one P(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Cr(2), one Cr(3), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(2), and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Cr(2), one Cr(3), and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Cr(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Cr(2), one Cr(3), and one P(2) atom. In the eighth O site, O(8) is bonded in a distorted linear geometry to one Cr(3) and one P(1) atom.