Ta4FeCoO12 is Hydrophilite-derived structured and crystallizes in the orthorhombic Cmmm space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form TaO6 octahedra that share corners with four equivalent Ta(2)O6 octahedra, corners with four equivalent Co(1)O6 octahedra,  an edgeedge with one Ta(1)O6 octahedra, and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-52°. In the second Ta site, Ta(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form TaO6 octahedra that share corners with four equivalent Ta(1)O6 octahedra, corners with four equivalent Fe(1)O6 octahedra,  an edgeedge with one Ta(2)O6 octahedra, and  an edgeedge with one Co(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-53°. Fe(1) is bonded to two equivalent O(1) and four equivalent O(4) atoms to form FeO6 octahedra that share corners with eight equivalent Ta(2)O6 octahedra and edges with two equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-53°. Co(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form CoO6 octahedra that share corners with eight equivalent Ta(1)O6 octahedra and edges with two equivalent Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-52°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to two equivalent Ta(2) and one Fe(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to two equivalent Ta(1) and one Co(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Ta(1), one Ta(2), and one Co(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Ta(1), one Ta(2), and one Fe(1) atom.
Ta4FeCoO12 is Hydrophilite-derived structured and crystallizes in the orthorhombic Cmmm space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form TaO6 octahedra that share corners with four equivalent Ta(2)O6 octahedra, corners with four equivalent Co(1)O6 octahedra,  an edgeedge with one Ta(1)O6 octahedra, and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-52°. Both Ta(1)-O(2) bond lengths are 2.02 Å. Both Ta(1)-O(3) bond lengths are 2.01 Å. Both Ta(1)-O(4) bond lengths are 1.98 Å. In the second Ta site, Ta(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form TaO6 octahedra that share corners with four equivalent Ta(1)O6 octahedra, corners with four equivalent Fe(1)O6 octahedra,  an edgeedge with one Ta(2)O6 octahedra, and  an edgeedge with one Co(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-53°. Both Ta(2)-O(1) bond lengths are 2.03 Å. Both Ta(2)-O(3) bond lengths are 1.98 Å. Both Ta(2)-O(4) bond lengths are 2.00 Å. Fe(1) is bonded to two equivalent O(1) and four equivalent O(4) atoms to form FeO6 octahedra that share corners with eight equivalent Ta(2)O6 octahedra and edges with two equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-53°. Both Fe(1)-O(1) bond lengths are 2.12 Å. All Fe(1)-O(4) bond lengths are 2.18 Å. Co(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form CoO6 octahedra that share corners with eight equivalent Ta(1)O6 octahedra and edges with two equivalent Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-52°. Both Co(1)-O(2) bond lengths are 2.13 Å. All Co(1)-O(3) bond lengths are 2.15 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to two equivalent Ta(2) and one Fe(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to two equivalent Ta(1) and one Co(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Ta(1), one Ta(2), and one Co(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Ta(1), one Ta(2), and one Fe(1) atom.