U2Fe12P7 crystallizes in the hexagonal P-6 space group. There are two inequivalent U sites. In the first U site, U(1) is bonded in a 18-coordinate geometry to three equivalent Fe(1), three equivalent Fe(3), six equivalent Fe(2), and six equivalent P(1) atoms. In the second U site, U(2) is bonded to six equivalent Fe(3) and six equivalent P(3) atoms to form distorted UFe6P6 cuboctahedra that share corners with six equivalent Fe(2)U2P4 tetrahedra, corners with six equivalent Fe(1)UP4 tetrahedra, edges with three equivalent Fe(2)U2P4 tetrahedra, and faces with two equivalent U(2)Fe6P6 cuboctahedra. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one U(1), one P(2), one P(3), and two equivalent P(1) atoms to form distorted FeUP4 tetrahedra that share corners with two equivalent U(2)Fe6P6 cuboctahedra, corners with two equivalent Fe(2)U2P4 tetrahedra, corners with six equivalent Fe(1)UP4 tetrahedra, edges with two equivalent Fe(2)U2P4 tetrahedra, and faces with two equivalent Fe(2)U2P4 tetrahedra. In the second Fe site, Fe(2) is bonded to two equivalent U(1), two equivalent P(1), and two equivalent P(3) atoms to form distorted FeU2P4 tetrahedra that share corners with two equivalent U(2)Fe6P6 cuboctahedra, corners with two equivalent Fe(1)UP4 tetrahedra, corners with four equivalent Fe(2)U2P4 tetrahedra,  an edgeedge with one U(2)Fe6P6 cuboctahedra, edges with two equivalent Fe(2)U2P4 tetrahedra, edges with two equivalent Fe(1)UP4 tetrahedra, faces with two equivalent Fe(2)U2P4 tetrahedra, and faces with two equivalent Fe(1)UP4 tetrahedra. In the third Fe site, Fe(3) is bonded in a 4-coordinate geometry to one U(1), two equivalent U(2), two equivalent P(1), and two equivalent P(3) atoms. In the fourth Fe site, Fe(4) is bonded in a 5-coordinate geometry to one P(1), two equivalent P(2), and two equivalent P(3) atoms. There are three inequivalent P sites. In the first P site, P(1) is bonded in a 9-coordinate geometry to two equivalent U(1), one Fe(4), two equivalent Fe(1), two equivalent Fe(2), and two equivalent Fe(3) atoms. In the second P site, P(2) is bonded in a 9-coordinate geometry to three equivalent Fe(1) and six equivalent Fe(4) atoms. In the third P site, P(3) is bonded in a 9-coordinate geometry to two equivalent U(2), one Fe(1), two equivalent Fe(2), two equivalent Fe(3), and two equivalent Fe(4) atoms.
U2Fe12P7 crystallizes in the hexagonal P-6 space group. There are two inequivalent U sites. In the first U site, U(1) is bonded in a 18-coordinate geometry to three equivalent Fe(1), three equivalent Fe(3), six equivalent Fe(2), and six equivalent P(1) atoms. All U(1)-Fe(1) bond lengths are 3.04 Å. All U(1)-Fe(3) bond lengths are 3.24 Å. All U(1)-Fe(2) bond lengths are 2.92 Å. All U(1)-P(1) bond lengths are 2.87 Å. In the second U site, U(2) is bonded to six equivalent Fe(3) and six equivalent P(3) atoms to form distorted UFe6P6 cuboctahedra that share corners with six equivalent Fe(2)U2P4 tetrahedra, corners with six equivalent Fe(1)UP4 tetrahedra, edges with three equivalent Fe(2)U2P4 tetrahedra, and faces with two equivalent U(2)Fe6P6 cuboctahedra. All U(2)-Fe(3) bond lengths are 2.90 Å. All U(2)-P(3) bond lengths are 2.87 Å. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one U(1), one P(2), one P(3), and two equivalent P(1) atoms to form distorted FeUP4 tetrahedra that share corners with two equivalent U(2)Fe6P6 cuboctahedra, corners with two equivalent Fe(2)U2P4 tetrahedra, corners with six equivalent Fe(1)UP4 tetrahedra, edges with two equivalent Fe(2)U2P4 tetrahedra, and faces with two equivalent Fe(2)U2P4 tetrahedra. The Fe(1)-P(2) bond length is 2.15 Å. The Fe(1)-P(3) bond length is 2.18 Å. Both Fe(1)-P(1) bond lengths are 2.25 Å. In the second Fe site, Fe(2) is bonded to two equivalent U(1), two equivalent P(1), and two equivalent P(3) atoms to form distorted FeU2P4 tetrahedra that share corners with two equivalent U(2)Fe6P6 cuboctahedra, corners with two equivalent Fe(1)UP4 tetrahedra, corners with four equivalent Fe(2)U2P4 tetrahedra,  an edgeedge with one U(2)Fe6P6 cuboctahedra, edges with two equivalent Fe(2)U2P4 tetrahedra, edges with two equivalent Fe(1)UP4 tetrahedra, faces with two equivalent Fe(2)U2P4 tetrahedra, and faces with two equivalent Fe(1)UP4 tetrahedra. There is one shorter (2.23 Å) and one longer (2.29 Å) Fe(2)-P(1) bond length. Both Fe(2)-P(3) bond lengths are 2.26 Å. In the third Fe site, Fe(3) is bonded in a 4-coordinate geometry to one U(1), two equivalent U(2), two equivalent P(1), and two equivalent P(3) atoms. Both Fe(3)-P(1) bond lengths are 2.33 Å. There is one shorter (2.22 Å) and one longer (2.26 Å) Fe(3)-P(3) bond length. In the fourth Fe site, Fe(4) is bonded in a 5-coordinate geometry to one P(1), two equivalent P(2), and two equivalent P(3) atoms. The Fe(4)-P(1) bond length is 2.28 Å. Both Fe(4)-P(2) bond lengths are 2.50 Å. Both Fe(4)-P(3) bond lengths are 2.53 Å. There are three inequivalent P sites. In the first P site, P(1) is bonded in a 9-coordinate geometry to two equivalent U(1), one Fe(4), two equivalent Fe(1), two equivalent Fe(2), and two equivalent Fe(3) atoms. In the second P site, P(2) is bonded in a 9-coordinate geometry to three equivalent Fe(1) and six equivalent Fe(4) atoms. In the third P site, P(3) is bonded in a 9-coordinate geometry to two equivalent U(2), one Fe(1), two equivalent Fe(2), two equivalent Fe(3), and two equivalent Fe(4) atoms.