Sr4N3 crystallizes in the monoclinic C2/m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one N(2) and three equivalent N(1) atoms to form SrN4 trigonal pyramids that share corners with seven equivalent Sr(2)N5 trigonal bipyramids, corners with three equivalent Sr(1)N4 trigonal pyramids, edges with three equivalent Sr(2)N5 trigonal bipyramids, and edges with two equivalent Sr(1)N4 trigonal pyramids. In the second Sr site, Sr(2) is bonded to two equivalent N(2) and three equivalent N(1) atoms to form distorted SrN5 trigonal bipyramids that share corners with two equivalent Sr(2)N5 trigonal bipyramids, corners with seven equivalent Sr(1)N4 trigonal pyramids, edges with five equivalent Sr(2)N5 trigonal bipyramids, and edges with three equivalent Sr(1)N4 trigonal pyramids. There are two inequivalent N sites. In the first N site, N(1) is bonded to three equivalent Sr(1) and three equivalent Sr(2) atoms to form a mixture of corner, edge, and face-sharing NSr6 octahedra. The corner-sharing octahedral tilt angles range from 41-58°. In the second N site, N(2) is bonded to two equivalent Sr(1) and four equivalent Sr(2) atoms to form a mixture of corner, edge, and face-sharing NSr6 octahedra. The corner-sharing octahedral tilt angles range from 41-58°.
Sr4N3 crystallizes in the monoclinic C2/m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one N(2) and three equivalent N(1) atoms to form SrN4 trigonal pyramids that share corners with seven equivalent Sr(2)N5 trigonal bipyramids, corners with three equivalent Sr(1)N4 trigonal pyramids, edges with three equivalent Sr(2)N5 trigonal bipyramids, and edges with two equivalent Sr(1)N4 trigonal pyramids. The Sr(1)-N(2) bond length is 2.66 Å. There are two shorter (2.55 Å) and one longer (2.58 Å) Sr(1)-N(1) bond length. In the second Sr site, Sr(2) is bonded to two equivalent N(2) and three equivalent N(1) atoms to form distorted SrN5 trigonal bipyramids that share corners with two equivalent Sr(2)N5 trigonal bipyramids, corners with seven equivalent Sr(1)N4 trigonal pyramids, edges with five equivalent Sr(2)N5 trigonal bipyramids, and edges with three equivalent Sr(1)N4 trigonal pyramids. Both Sr(2)-N(2) bond lengths are 2.72 Å. There is one shorter (2.63 Å) and two longer (2.79 Å) Sr(2)-N(1) bond lengths. There are two inequivalent N sites. In the first N site, N(1) is bonded to three equivalent Sr(1) and three equivalent Sr(2) atoms to form a mixture of corner, edge, and face-sharing NSr6 octahedra. The corner-sharing octahedral tilt angles range from 41-58°. In the second N site, N(2) is bonded to two equivalent Sr(1) and four equivalent Sr(2) atoms to form a mixture of corner, edge, and face-sharing NSr6 octahedra. The corner-sharing octahedral tilt angles range from 41-58°.