Hf7P4 crystallizes in the monoclinic C2/m space group. There are eight inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a 5-coordinate geometry to two equivalent P(1) and three equivalent P(4) atoms. In the second Hf site, Hf(2) is bonded to one P(1), two equivalent P(2), and two equivalent P(3) atoms to form a mixture of distorted corner, edge, and face-sharing HfP5 trigonal bipyramids. In the third Hf site, Hf(3) is bonded in a 5-coordinate geometry to two equivalent P(2) and three equivalent P(3) atoms. In the fourth Hf site, Hf(4) is bonded to one P(1), two equivalent P(2), and two equivalent P(4) atoms to form a mixture of distorted corner, edge, and face-sharing HfP5 trigonal bipyramids. In the fifth Hf site, Hf(5) is bonded in a 4-coordinate geometry to one P(2), one P(4), and two equivalent P(3) atoms. In the sixth Hf site, Hf(6) is bonded in a 4-coordinate geometry to one P(3), two equivalent P(1), and two equivalent P(4) atoms. In the seventh Hf site, Hf(7) is bonded in a square co-planar geometry to two equivalent P(2) and two equivalent P(3) atoms. In the eighth Hf site, Hf(8) is bonded in a distorted square co-planar geometry to two equivalent P(1) and two equivalent P(4) atoms. There are four inequivalent P sites. In the first P site, P(3) is bonded in a 9-coordinate geometry to one Hf(6), one Hf(7), two equivalent Hf(2), two equivalent Hf(5), and three equivalent Hf(3) atoms. In the second P site, P(4) is bonded in a 9-coordinate geometry to one Hf(5), one Hf(8), two equivalent Hf(4), two equivalent Hf(6), and three equivalent Hf(1) atoms. In the third P site, P(1) is bonded to one Hf(2), one Hf(4), one Hf(8), two equivalent Hf(1), and two equivalent Hf(6) atoms to form a mixture of distorted corner and edge-sharing PHf7 pentagonal bipyramids. In the fourth P site, P(2) is bonded in a 8-coordinate geometry to one Hf(5), one Hf(7), two equivalent Hf(2), two equivalent Hf(3), and two equivalent Hf(4) atoms.
Hf7P4 crystallizes in the monoclinic C2/m space group. There are eight inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a 5-coordinate geometry to two equivalent P(1) and three equivalent P(4) atoms. Both Hf(1)-P(1) bond lengths are 2.67 Å. There are two shorter (2.67 Å) and one longer (3.04 Å) Hf(1)-P(4) bond length. In the second Hf site, Hf(2) is bonded to one P(1), two equivalent P(2), and two equivalent P(3) atoms to form a mixture of distorted corner, edge, and face-sharing HfP5 trigonal bipyramids. The Hf(2)-P(1) bond length is 2.62 Å. Both Hf(2)-P(2) bond lengths are 2.67 Å. Both Hf(2)-P(3) bond lengths are 2.67 Å. In the third Hf site, Hf(3) is bonded in a 5-coordinate geometry to two equivalent P(2) and three equivalent P(3) atoms. Both Hf(3)-P(2) bond lengths are 2.71 Å. There are two shorter (2.68 Å) and one longer (3.00 Å) Hf(3)-P(3) bond length. In the fourth Hf site, Hf(4) is bonded to one P(1), two equivalent P(2), and two equivalent P(4) atoms to form a mixture of distorted corner, edge, and face-sharing HfP5 trigonal bipyramids. The Hf(4)-P(1) bond length is 2.55 Å. Both Hf(4)-P(2) bond lengths are 2.70 Å. Both Hf(4)-P(4) bond lengths are 2.66 Å. In the fifth Hf site, Hf(5) is bonded in a 4-coordinate geometry to one P(2), one P(4), and two equivalent P(3) atoms. The Hf(5)-P(2) bond length is 2.65 Å. The Hf(5)-P(4) bond length is 2.88 Å. Both Hf(5)-P(3) bond lengths are 2.61 Å. In the sixth Hf site, Hf(6) is bonded in a 4-coordinate geometry to one P(3), two equivalent P(1), and two equivalent P(4) atoms. The Hf(6)-P(3) bond length is 3.31 Å. Both Hf(6)-P(1) bond lengths are 2.68 Å. Both Hf(6)-P(4) bond lengths are 2.71 Å. In the seventh Hf site, Hf(7) is bonded in a square co-planar geometry to two equivalent P(2) and two equivalent P(3) atoms. Both Hf(7)-P(2) bond lengths are 2.70 Å. Both Hf(7)-P(3) bond lengths are 2.72 Å. In the eighth Hf site, Hf(8) is bonded in a distorted square co-planar geometry to two equivalent P(1) and two equivalent P(4) atoms. Both Hf(8)-P(1) bond lengths are 2.59 Å. Both Hf(8)-P(4) bond lengths are 2.85 Å. There are four inequivalent P sites. In the first P site, P(3) is bonded in a 9-coordinate geometry to one Hf(6), one Hf(7), two equivalent Hf(2), two equivalent Hf(5), and three equivalent Hf(3) atoms. In the second P site, P(4) is bonded in a 9-coordinate geometry to one Hf(5), one Hf(8), two equivalent Hf(4), two equivalent Hf(6), and three equivalent Hf(1) atoms. In the third P site, P(1) is bonded to one Hf(2), one Hf(4), one Hf(8), two equivalent Hf(1), and two equivalent Hf(6) atoms to form a mixture of distorted corner and edge-sharing PHf7 pentagonal bipyramids. In the fourth P site, P(2) is bonded in a 8-coordinate geometry to one Hf(5), one Hf(7), two equivalent Hf(2), two equivalent Hf(3), and two equivalent Hf(4) atoms.