P4N7 crystallizes in the monoclinic C2/c space group. There are two inequivalent P sites. In the first P site, P(1) is bonded to one N(1), one N(2), one N(3), and one N(4) atom to form PN4 tetrahedra that share  a cornercorner with one P(1)N4 tetrahedra and corners with five equivalent P(2)N5 trigonal bipyramids. In the second P site, P(2) is bonded to one N(1), two equivalent N(2), and two equivalent N(4) atoms to form PN5 trigonal bipyramids that share corners with five equivalent P(1)N4 tetrahedra and edges with two equivalent P(2)N5 trigonal bipyramids. There are four inequivalent N sites. In the first N site, N(1) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the second N site, N(2) is bonded in a trigonal planar geometry to one P(1) and two equivalent P(2) atoms. In the third N site, N(3) is bonded in a bent 150 degrees geometry to two equivalent P(1) atoms. In the fourth N site, N(4) is bonded in a distorted trigonal planar geometry to one P(1) and two equivalent P(2) atoms.
P4N7 crystallizes in the monoclinic C2/c space group. There are two inequivalent P sites. In the first P site, P(1) is bonded to one N(1), one N(2), one N(3), and one N(4) atom to form PN4 tetrahedra that share  a cornercorner with one P(1)N4 tetrahedra and corners with five equivalent P(2)N5 trigonal bipyramids. The P(1)-N(1) bond length is 1.59 Å. The P(1)-N(2) bond length is 1.69 Å. The P(1)-N(3) bond length is 1.59 Å. The P(1)-N(4) bond length is 1.69 Å. In the second P site, P(2) is bonded to one N(1), two equivalent N(2), and two equivalent N(4) atoms to form PN5 trigonal bipyramids that share corners with five equivalent P(1)N4 tetrahedra and edges with two equivalent P(2)N5 trigonal bipyramids. The P(2)-N(1) bond length is 1.62 Å. There is one shorter (1.69 Å) and one longer (1.84 Å) P(2)-N(2) bond length. There is one shorter (1.70 Å) and one longer (1.84 Å) P(2)-N(4) bond length. There are four inequivalent N sites. In the first N site, N(1) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the second N site, N(2) is bonded in a trigonal planar geometry to one P(1) and two equivalent P(2) atoms. In the third N site, N(3) is bonded in a bent 150 degrees geometry to two equivalent P(1) atoms. In the fourth N site, N(4) is bonded in a distorted trigonal planar geometry to one P(1) and two equivalent P(2) atoms.