Fe2Co(PO4)3 crystallizes in the trigonal R-3c space group. Fe(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted FeO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra and  a faceface with one Co(1)O6 octahedra. Co(1) is bonded to six equivalent O(2) atoms to form distorted CoO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra and faces with two equivalent Fe(1)O6 octahedra. P(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form PO4 tetrahedra that share corners with two equivalent Co(1)O6 octahedra and corners with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 29-53°. There are two inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Fe(1), one Co(1), and one P(1) atom.
Fe2Co(PO4)3 crystallizes in the trigonal R-3c space group. Fe(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted FeO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra and  a faceface with one Co(1)O6 octahedra. All Fe(1)-O(1) bond lengths are 1.93 Å. All Fe(1)-O(2) bond lengths are 2.10 Å. Co(1) is bonded to six equivalent O(2) atoms to form distorted CoO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra and faces with two equivalent Fe(1)O6 octahedra. All Co(1)-O(2) bond lengths are 2.10 Å. P(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form PO4 tetrahedra that share corners with two equivalent Co(1)O6 octahedra and corners with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 29-53°. Both P(1)-O(1) bond lengths are 1.52 Å. Both P(1)-O(2) bond lengths are 1.57 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Fe(1), one Co(1), and one P(1) atom.