FeMoO4 crystallizes in the triclinic P1 space group. There are four inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one O(10), one O(11), one O(5), and one O(8) atom to form MoO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, and corners with two equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 16-59°. In the second Mo site, Mo(2) is bonded to one O(12), one O(6), one O(7), and one O(9) atom to form MoO4 tetrahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, and corners with two equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 17-60°. In the third Mo site, Mo(3) is bonded to one O(13), one O(14), one O(2), and one O(3) atom to form MoO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, and corners with two equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-64°. In the fourth Mo site, Mo(4) is bonded to one O(1), one O(15), one O(16), and one O(4) atom to form MoO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, and corners with two equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-62°. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(10), one O(11), one O(14), one O(15), and one O(2) atom to form FeO6 octahedra that share corners with two equivalent Mo(1)O4 tetrahedra, corners with two equivalent Mo(3)O4 tetrahedra, corners with two equivalent Mo(4)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra, and  an edgeedge with one Fe(4)O6 octahedra. In the second Fe site, Fe(2) is bonded to one O(1), one O(12), one O(13), one O(16), one O(2), and one O(9) atom to form FeO6 octahedra that share corners with two equivalent Mo(2)O4 tetrahedra, corners with two equivalent Mo(3)O4 tetrahedra, corners with two equivalent Mo(4)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra, and  an edgeedge with one Fe(4)O6 octahedra. In the third Fe site, Fe(3) is bonded to one O(1), one O(10), one O(4), one O(5), one O(6), and one O(9) atom to form FeO6 octahedra that share corners with two equivalent Mo(1)O4 tetrahedra, corners with two equivalent Mo(2)O4 tetrahedra, corners with two equivalent Mo(4)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and  an edgeedge with one Fe(2)O6 octahedra. In the fourth Fe site, Fe(4) is bonded to one O(11), one O(12), one O(2), one O(3), one O(7), and one O(8) atom to form FeO6 octahedra that share corners with two equivalent Mo(1)O4 tetrahedra, corners with two equivalent Mo(2)O4 tetrahedra, corners with two equivalent Mo(3)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and  an edgeedge with one Fe(2)O6 octahedra. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded to one Mo(4), one Fe(1), one Fe(2), and one Fe(3) atom to form distorted edge-sharing OFe3Mo tetrahedra. In the second O site, O(2) is bonded to one Mo(3), one Fe(1), one Fe(2), and one Fe(4) atom to form distorted edge-sharing OFe3Mo tetrahedra. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Mo(3) and one Fe(4) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Mo(4) and one Fe(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Mo(1) and one Fe(3) atom. In the sixth O site, O(6) is bonded in a linear geometry to one Mo(2) and one Fe(3) atom. In the seventh O site, O(7) is bonded in a linear geometry to one Mo(2) and one Fe(4) atom. In the eighth O site, O(8) is bonded in a linear geometry to one Mo(1) and one Fe(4) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Mo(2), one Fe(2), and one Fe(3) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one Mo(1), one Fe(1), and one Fe(3) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Mo(1), one Fe(1), and one Fe(4) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Mo(2), one Fe(2), and one Fe(4) atom. In the thirteenth O site, O(13) is bonded in a linear geometry to one Mo(3) and one Fe(2) atom. In the fourteenth O site, O(14) is bonded in a linear geometry to one Mo(3) and one Fe(1) atom. In the fifteenth O site, O(15) is bonded in a linear geometry to one Mo(4) and one Fe(1) atom. In the sixteenth O site, O(16) is bonded in a linear geometry to one Mo(4) and one Fe(2) atom.
FeMoO4 crystallizes in the triclinic P1 space group. There are four inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one O(10), one O(11), one O(5), and one O(8) atom to form MoO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, and corners with two equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 16-59°. The Mo(1)-O(10) bond length is 1.83 Å. The Mo(1)-O(11) bond length is 1.81 Å. The Mo(1)-O(5) bond length is 1.75 Å. The Mo(1)-O(8) bond length is 1.74 Å. In the second Mo site, Mo(2) is bonded to one O(12), one O(6), one O(7), and one O(9) atom to form MoO4 tetrahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, and corners with two equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 17-60°. The Mo(2)-O(12) bond length is 1.82 Å. The Mo(2)-O(6) bond length is 1.75 Å. The Mo(2)-O(7) bond length is 1.74 Å. The Mo(2)-O(9) bond length is 1.83 Å. In the third Mo site, Mo(3) is bonded to one O(13), one O(14), one O(2), and one O(3) atom to form MoO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, and corners with two equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-64°. The Mo(3)-O(13) bond length is 1.74 Å. The Mo(3)-O(14) bond length is 1.74 Å. The Mo(3)-O(2) bond length is 1.86 Å. The Mo(3)-O(3) bond length is 1.79 Å. In the fourth Mo site, Mo(4) is bonded to one O(1), one O(15), one O(16), and one O(4) atom to form MoO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, and corners with two equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 13-62°. The Mo(4)-O(1) bond length is 1.85 Å. The Mo(4)-O(15) bond length is 1.75 Å. The Mo(4)-O(16) bond length is 1.75 Å. The Mo(4)-O(4) bond length is 1.77 Å. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(10), one O(11), one O(14), one O(15), and one O(2) atom to form FeO6 octahedra that share corners with two equivalent Mo(1)O4 tetrahedra, corners with two equivalent Mo(3)O4 tetrahedra, corners with two equivalent Mo(4)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra, and  an edgeedge with one Fe(4)O6 octahedra. The Fe(1)-O(1) bond length is 2.18 Å. The Fe(1)-O(10) bond length is 2.04 Å. The Fe(1)-O(11) bond length is 2.05 Å. The Fe(1)-O(14) bond length is 1.99 Å. The Fe(1)-O(15) bond length is 2.00 Å. The Fe(1)-O(2) bond length is 2.21 Å. In the second Fe site, Fe(2) is bonded to one O(1), one O(12), one O(13), one O(16), one O(2), and one O(9) atom to form FeO6 octahedra that share corners with two equivalent Mo(2)O4 tetrahedra, corners with two equivalent Mo(3)O4 tetrahedra, corners with two equivalent Mo(4)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra, and  an edgeedge with one Fe(4)O6 octahedra. The Fe(2)-O(1) bond length is 2.19 Å. The Fe(2)-O(12) bond length is 2.05 Å. The Fe(2)-O(13) bond length is 1.99 Å. The Fe(2)-O(16) bond length is 2.00 Å. The Fe(2)-O(2) bond length is 2.22 Å. The Fe(2)-O(9) bond length is 2.03 Å. In the third Fe site, Fe(3) is bonded to one O(1), one O(10), one O(4), one O(5), one O(6), and one O(9) atom to form FeO6 octahedra that share corners with two equivalent Mo(1)O4 tetrahedra, corners with two equivalent Mo(2)O4 tetrahedra, corners with two equivalent Mo(4)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and  an edgeedge with one Fe(2)O6 octahedra. The Fe(3)-O(1) bond length is 2.15 Å. The Fe(3)-O(10) bond length is 2.14 Å. The Fe(3)-O(4) bond length is 2.02 Å. The Fe(3)-O(5) bond length is 2.01 Å. The Fe(3)-O(6) bond length is 2.02 Å. The Fe(3)-O(9) bond length is 2.14 Å. In the fourth Fe site, Fe(4) is bonded to one O(11), one O(12), one O(2), one O(3), one O(7), and one O(8) atom to form FeO6 octahedra that share corners with two equivalent Mo(1)O4 tetrahedra, corners with two equivalent Mo(2)O4 tetrahedra, corners with two equivalent Mo(3)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and  an edgeedge with one Fe(2)O6 octahedra. The Fe(4)-O(11) bond length is 2.14 Å. The Fe(4)-O(12) bond length is 2.14 Å. The Fe(4)-O(2) bond length is 2.08 Å. The Fe(4)-O(3) bond length is 2.00 Å. The Fe(4)-O(7) bond length is 2.02 Å. The Fe(4)-O(8) bond length is 2.02 Å. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded to one Mo(4), one Fe(1), one Fe(2), and one Fe(3) atom to form distorted edge-sharing OFe3Mo tetrahedra. In the second O site, O(2) is bonded to one Mo(3), one Fe(1), one Fe(2), and one Fe(4) atom to form distorted edge-sharing OFe3Mo tetrahedra. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Mo(3) and one Fe(4) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Mo(4) and one Fe(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Mo(1) and one Fe(3) atom. In the sixth O site, O(6) is bonded in a linear geometry to one Mo(2) and one Fe(3) atom. In the seventh O site, O(7) is bonded in a linear geometry to one Mo(2) and one Fe(4) atom. In the eighth O site, O(8) is bonded in a linear geometry to one Mo(1) and one Fe(4) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Mo(2), one Fe(2), and one Fe(3) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one Mo(1), one Fe(1), and one Fe(3) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Mo(1), one Fe(1), and one Fe(4) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Mo(2), one Fe(2), and one Fe(4) atom. In the thirteenth O site, O(13) is bonded in a linear geometry to one Mo(3) and one Fe(2) atom. In the fourteenth O site, O(14) is bonded in a linear geometry to one Mo(3) and one Fe(1) atom. In the fifteenth O site, O(15) is bonded in a linear geometry to one Mo(4) and one Fe(1) atom. In the sixteenth O site, O(16) is bonded in a linear geometry to one Mo(4) and one Fe(2) atom.