LaP7 crystallizes in the monoclinic P2_1/c space group. La(1) is bonded in a 10-coordinate geometry to one P(1), one P(2), one P(3), one P(6), two equivalent P(4), two equivalent P(5), and two equivalent P(7) atoms. There are seven inequivalent P sites. In the first P site, P(1) is bonded to one La(1), one P(4), one P(5), and one P(7) atom to form PLaP3 tetrahedra that share corners with two equivalent P(5)La2P2 tetrahedra, corners with two equivalent P(7)La2P2 tetrahedra, corners with two equivalent P(2)LaP3 tetrahedra, corners with two equivalent P(3)LaP3 tetrahedra, corners with two equivalent P(6)LaP3 tetrahedra, and corners with two equivalent P(4)La2P2 trigonal pyramids. In the second P site, P(2) is bonded to one La(1), one P(2), one P(3), and one P(7) atom to form PLaP3 tetrahedra that share corners with two equivalent P(1)LaP3 tetrahedra, corners with two equivalent P(3)LaP3 tetrahedra, corners with two equivalent P(6)LaP3 tetrahedra, corners with three equivalent P(5)La2P2 tetrahedra, corners with three equivalent P(7)La2P2 tetrahedra, and corners with two equivalent P(4)La2P2 trigonal pyramids. In the third P site, P(3) is bonded to one La(1), one P(2), one P(5), and one P(6) atom to form PLaP3 tetrahedra that share  a cornercorner with one P(7)La2P2 tetrahedra, corners with two equivalent P(5)La2P2 tetrahedra, corners with two equivalent P(1)LaP3 tetrahedra, corners with two equivalent P(2)LaP3 tetrahedra, corners with two equivalent P(6)LaP3 tetrahedra, corners with three equivalent P(4)La2P2 trigonal pyramids, and  an edgeedge with one P(7)La2P2 tetrahedra. In the fourth P site, P(4) is bonded to two equivalent La(1), one P(1), and one P(6) atom to form PLa2P2 trigonal pyramids that share corners with two equivalent P(1)LaP3 tetrahedra, corners with two equivalent P(2)LaP3 tetrahedra, corners with three equivalent P(5)La2P2 tetrahedra, corners with three equivalent P(7)La2P2 tetrahedra, corners with three equivalent P(3)LaP3 tetrahedra, corners with three equivalent P(6)LaP3 tetrahedra, corners with two equivalent P(4)La2P2 trigonal pyramids,  an edgeedge with one P(5)La2P2 tetrahedra, and  an edgeedge with one P(7)La2P2 tetrahedra. In the fifth P site, P(5) is bonded to two equivalent La(1), one P(1), and one P(3) atom to form PLa2P2 tetrahedra that share corners with two equivalent P(1)LaP3 tetrahedra, corners with two equivalent P(3)LaP3 tetrahedra, corners with three equivalent P(2)LaP3 tetrahedra, corners with three equivalent P(6)LaP3 tetrahedra, corners with five equivalent P(7)La2P2 tetrahedra, corners with three equivalent P(4)La2P2 trigonal pyramids,  an edgeedge with one P(5)La2P2 tetrahedra, and  an edgeedge with one P(4)La2P2 trigonal pyramid. In the sixth P site, P(6) is bonded to one La(1), one P(3), one P(4), and one P(6) atom to form PLaP3 tetrahedra that share corners with two equivalent P(7)La2P2 tetrahedra, corners with two equivalent P(1)LaP3 tetrahedra, corners with two equivalent P(2)LaP3 tetrahedra, corners with two equivalent P(3)LaP3 tetrahedra, corners with three equivalent P(5)La2P2 tetrahedra, and corners with three equivalent P(4)La2P2 trigonal pyramids. In the seventh P site, P(7) is bonded to two equivalent La(1), one P(1), and one P(2) atom to form PLa2P2 tetrahedra that share  a cornercorner with one P(3)LaP3 tetrahedra, corners with two equivalent P(7)La2P2 tetrahedra, corners with two equivalent P(1)LaP3 tetrahedra, corners with two equivalent P(6)LaP3 tetrahedra, corners with three equivalent P(2)LaP3 tetrahedra, corners with five equivalent P(5)La2P2 tetrahedra, corners with three equivalent P(4)La2P2 trigonal pyramids,  an edgeedge with one P(3)LaP3 tetrahedra, and  an edgeedge with one P(4)La2P2 trigonal pyramid.
LaP7 crystallizes in the monoclinic P2_1/c space group. La(1) is bonded in a 10-coordinate geometry to one P(1), one P(2), one P(3), one P(6), two equivalent P(4), two equivalent P(5), and two equivalent P(7) atoms. The La(1)-P(1) bond length is 3.17 Å. The La(1)-P(2) bond length is 3.26 Å. The La(1)-P(3) bond length is 3.21 Å. The La(1)-P(6) bond length is 3.26 Å. There is one shorter (3.21 Å) and one longer (3.26 Å) La(1)-P(4) bond length. There is one shorter (3.22 Å) and one longer (3.25 Å) La(1)-P(5) bond length. There is one shorter (3.08 Å) and one longer (3.18 Å) La(1)-P(7) bond length. There are seven inequivalent P sites. In the first P site, P(1) is bonded to one La(1), one P(4), one P(5), and one P(7) atom to form PLaP3 tetrahedra that share corners with two equivalent P(5)La2P2 tetrahedra, corners with two equivalent P(7)La2P2 tetrahedra, corners with two equivalent P(2)LaP3 tetrahedra, corners with two equivalent P(3)LaP3 tetrahedra, corners with two equivalent P(6)LaP3 tetrahedra, and corners with two equivalent P(4)La2P2 trigonal pyramids. The P(1)-P(4) bond length is 2.21 Å. The P(1)-P(5) bond length is 2.21 Å. The P(1)-P(7) bond length is 2.24 Å. In the second P site, P(2) is bonded to one La(1), one P(2), one P(3), and one P(7) atom to form PLaP3 tetrahedra that share corners with two equivalent P(1)LaP3 tetrahedra, corners with two equivalent P(3)LaP3 tetrahedra, corners with two equivalent P(6)LaP3 tetrahedra, corners with three equivalent P(5)La2P2 tetrahedra, corners with three equivalent P(7)La2P2 tetrahedra, and corners with two equivalent P(4)La2P2 trigonal pyramids. The P(2)-P(2) bond length is 2.18 Å. The P(2)-P(3) bond length is 2.20 Å. The P(2)-P(7) bond length is 2.18 Å. In the third P site, P(3) is bonded to one La(1), one P(2), one P(5), and one P(6) atom to form PLaP3 tetrahedra that share  a cornercorner with one P(7)La2P2 tetrahedra, corners with two equivalent P(5)La2P2 tetrahedra, corners with two equivalent P(1)LaP3 tetrahedra, corners with two equivalent P(2)LaP3 tetrahedra, corners with two equivalent P(6)LaP3 tetrahedra, corners with three equivalent P(4)La2P2 trigonal pyramids, and  an edgeedge with one P(7)La2P2 tetrahedra. The P(3)-P(5) bond length is 2.16 Å. The P(3)-P(6) bond length is 2.18 Å. In the fourth P site, P(4) is bonded to two equivalent La(1), one P(1), and one P(6) atom to form PLa2P2 trigonal pyramids that share corners with two equivalent P(1)LaP3 tetrahedra, corners with two equivalent P(2)LaP3 tetrahedra, corners with three equivalent P(5)La2P2 tetrahedra, corners with three equivalent P(7)La2P2 tetrahedra, corners with three equivalent P(3)LaP3 tetrahedra, corners with three equivalent P(6)LaP3 tetrahedra, corners with two equivalent P(4)La2P2 trigonal pyramids,  an edgeedge with one P(5)La2P2 tetrahedra, and  an edgeedge with one P(7)La2P2 tetrahedra. The P(4)-P(6) bond length is 2.16 Å. In the fifth P site, P(5) is bonded to two equivalent La(1), one P(1), and one P(3) atom to form PLa2P2 tetrahedra that share corners with two equivalent P(1)LaP3 tetrahedra, corners with two equivalent P(3)LaP3 tetrahedra, corners with three equivalent P(2)LaP3 tetrahedra, corners with three equivalent P(6)LaP3 tetrahedra, corners with five equivalent P(7)La2P2 tetrahedra, corners with three equivalent P(4)La2P2 trigonal pyramids,  an edgeedge with one P(5)La2P2 tetrahedra, and  an edgeedge with one P(4)La2P2 trigonal pyramid. In the sixth P site, P(6) is bonded to one La(1), one P(3), one P(4), and one P(6) atom to form PLaP3 tetrahedra that share corners with two equivalent P(7)La2P2 tetrahedra, corners with two equivalent P(1)LaP3 tetrahedra, corners with two equivalent P(2)LaP3 tetrahedra, corners with two equivalent P(3)LaP3 tetrahedra, corners with three equivalent P(5)La2P2 tetrahedra, and corners with three equivalent P(4)La2P2 trigonal pyramids. The P(6)-P(6) bond length is 2.19 Å. In the seventh P site, P(7) is bonded to two equivalent La(1), one P(1), and one P(2) atom to form PLa2P2 tetrahedra that share  a cornercorner with one P(3)LaP3 tetrahedra, corners with two equivalent P(7)La2P2 tetrahedra, corners with two equivalent P(1)LaP3 tetrahedra, corners with two equivalent P(6)LaP3 tetrahedra, corners with three equivalent P(2)LaP3 tetrahedra, corners with five equivalent P(5)La2P2 tetrahedra, corners with three equivalent P(4)La2P2 trigonal pyramids,  an edgeedge with one P(3)LaP3 tetrahedra, and  an edgeedge with one P(4)La2P2 trigonal pyramid.