SiPN3 crystallizes in the monoclinic P2_1 space group. Si(1) is bonded to one N(2), one N(3), and two equivalent N(1) atoms to form SiN4 tetrahedra that share corners with two equivalent Si(1)N4 tetrahedra and corners with five equivalent P(1)N4 tetrahedra. P(1) is bonded to one N(1), one N(3), and two equivalent N(2) atoms to form PN4 tetrahedra that share corners with two equivalent P(1)N4 tetrahedra and corners with five equivalent Si(1)N4 tetrahedra. There are three inequivalent N sites. In the first N site, N(1) is bonded in a trigonal planar geometry to two equivalent Si(1) and one P(1) atom. In the second N site, N(2) is bonded in a trigonal planar geometry to one Si(1) and two equivalent P(1) atoms. In the third N site, N(3) is bonded in a bent 150 degrees geometry to one Si(1) and one P(1) atom.
SiPN3 crystallizes in the monoclinic P2_1 space group. Si(1) is bonded to one N(2), one N(3), and two equivalent N(1) atoms to form SiN4 tetrahedra that share corners with two equivalent Si(1)N4 tetrahedra and corners with five equivalent P(1)N4 tetrahedra. The Si(1)-N(2) bond length is 1.79 Å. The Si(1)-N(3) bond length is 1.65 Å. There is one shorter (1.75 Å) and one longer (1.76 Å) Si(1)-N(1) bond length. P(1) is bonded to one N(1), one N(3), and two equivalent N(2) atoms to form PN4 tetrahedra that share corners with two equivalent P(1)N4 tetrahedra and corners with five equivalent Si(1)N4 tetrahedra. The P(1)-N(1) bond length is 1.67 Å. The P(1)-N(3) bond length is 1.55 Å. Both P(1)-N(2) bond lengths are 1.70 Å. There are three inequivalent N sites. In the first N site, N(1) is bonded in a trigonal planar geometry to two equivalent Si(1) and one P(1) atom. In the second N site, N(2) is bonded in a trigonal planar geometry to one Si(1) and two equivalent P(1) atoms. In the third N site, N(3) is bonded in a bent 150 degrees geometry to one Si(1) and one P(1) atom.