Sr3(NiN2)2 crystallizes in the monoclinic C2/c space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to two equivalent N(2) and four equivalent N(1) atoms. In the second Sr site, Sr(2) is bonded to two equivalent N(1) and four equivalent N(2) atoms to form distorted SrN6 octahedra that share corners with four equivalent Ni(1)N4 tetrahedra, edges with two equivalent Sr(2)N6 octahedra, and edges with four equivalent Ni(1)N4 tetrahedra. Ni(1) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form NiN4 tetrahedra that share corners with two equivalent Sr(2)N6 octahedra, corners with two equivalent Ni(1)N4 tetrahedra, edges with two equivalent Sr(2)N6 octahedra, and  an edgeedge with one Ni(1)N4 tetrahedra. The corner-sharing octahedral tilt angles range from 42-51°. There are two inequivalent N sites. In the first N site, N(1) is bonded in a 7-coordinate geometry to one Sr(2), four equivalent Sr(1), and two equivalent Ni(1) atoms. In the second N site, N(2) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Ni(1) atoms.
Sr3(NiN2)2 crystallizes in the monoclinic C2/c space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to two equivalent N(2) and four equivalent N(1) atoms. There is one shorter (2.56 Å) and one longer (2.73 Å) Sr(1)-N(2) bond length. There are a spread of Sr(1)-N(1) bond distances ranging from 2.66-3.12 Å. In the second Sr site, Sr(2) is bonded to two equivalent N(1) and four equivalent N(2) atoms to form distorted SrN6 octahedra that share corners with four equivalent Ni(1)N4 tetrahedra, edges with two equivalent Sr(2)N6 octahedra, and edges with four equivalent Ni(1)N4 tetrahedra. Both Sr(2)-N(1) bond lengths are 2.70 Å. There are two shorter (2.55 Å) and two longer (2.68 Å) Sr(2)-N(2) bond lengths. Ni(1) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form NiN4 tetrahedra that share corners with two equivalent Sr(2)N6 octahedra, corners with two equivalent Ni(1)N4 tetrahedra, edges with two equivalent Sr(2)N6 octahedra, and  an edgeedge with one Ni(1)N4 tetrahedra. The corner-sharing octahedral tilt angles range from 42-51°. There is one shorter (1.94 Å) and one longer (1.97 Å) Ni(1)-N(1) bond length. There is one shorter (1.91 Å) and one longer (1.99 Å) Ni(1)-N(2) bond length. There are two inequivalent N sites. In the first N site, N(1) is bonded in a 7-coordinate geometry to one Sr(2), four equivalent Sr(1), and two equivalent Ni(1) atoms. In the second N site, N(2) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Ni(1) atoms.