Sr3(NbN2)2 crystallizes in the monoclinic C2/c space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form distorted SrN4 trigonal pyramids that share corners with two equivalent Sr(1)N4 trigonal pyramids, corners with four equivalent Nb(1)N4 trigonal pyramids,  an edgeedge with one Sr(1)N4 trigonal pyramid, and edges with two equivalent Nb(1)N4 trigonal pyramids. In the second Sr site, Sr(2) is bonded in a bent 150 degrees geometry to two equivalent N(1) atoms. Nb(1) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form distorted NbN4 trigonal pyramids that share corners with two equivalent Nb(1)N4 trigonal pyramids, corners with four equivalent Sr(1)N4 trigonal pyramids,  an edgeedge with one Nb(1)N4 trigonal pyramid, and edges with two equivalent Sr(1)N4 trigonal pyramids. There are two inequivalent N sites. In the first N site, N(1) is bonded to one Sr(2), two equivalent Sr(1), and two equivalent Nb(1) atoms to form NSr3Nb2 trigonal bipyramids that share corners with three equivalent N(1)Sr3Nb2 trigonal bipyramids, corners with four equivalent N(2)Sr2Nb2 trigonal pyramids,  an edgeedge with one N(1)Sr3Nb2 trigonal bipyramid, and edges with two equivalent N(2)Sr2Nb2 trigonal pyramids. In the second N site, N(2) is bonded to two equivalent Sr(1) and two equivalent Nb(1) atoms to form NSr2Nb2 trigonal pyramids that share corners with four equivalent N(1)Sr3Nb2 trigonal bipyramids, corners with two equivalent N(2)Sr2Nb2 trigonal pyramids, edges with two equivalent N(1)Sr3Nb2 trigonal bipyramids, and  an edgeedge with one N(2)Sr2Nb2 trigonal pyramid.
Sr3(NbN2)2 crystallizes in the monoclinic C2/c space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form distorted SrN4 trigonal pyramids that share corners with two equivalent Sr(1)N4 trigonal pyramids, corners with four equivalent Nb(1)N4 trigonal pyramids,  an edgeedge with one Sr(1)N4 trigonal pyramid, and edges with two equivalent Nb(1)N4 trigonal pyramids. There is one shorter (2.65 Å) and one longer (2.73 Å) Sr(1)-N(1) bond length. There is one shorter (2.56 Å) and one longer (2.66 Å) Sr(1)-N(2) bond length. In the second Sr site, Sr(2) is bonded in a bent 150 degrees geometry to two equivalent N(1) atoms. Both Sr(2)-N(1) bond lengths are 2.72 Å. Nb(1) is bonded to two equivalent N(1) and two equivalent N(2) atoms to form distorted NbN4 trigonal pyramids that share corners with two equivalent Nb(1)N4 trigonal pyramids, corners with four equivalent Sr(1)N4 trigonal pyramids,  an edgeedge with one Nb(1)N4 trigonal pyramid, and edges with two equivalent Sr(1)N4 trigonal pyramids. There is one shorter (2.08 Å) and one longer (2.09 Å) Nb(1)-N(1) bond length. There is one shorter (1.97 Å) and one longer (1.99 Å) Nb(1)-N(2) bond length. There are two inequivalent N sites. In the first N site, N(1) is bonded to one Sr(2), two equivalent Sr(1), and two equivalent Nb(1) atoms to form NSr3Nb2 trigonal bipyramids that share corners with three equivalent N(1)Sr3Nb2 trigonal bipyramids, corners with four equivalent N(2)Sr2Nb2 trigonal pyramids,  an edgeedge with one N(1)Sr3Nb2 trigonal bipyramid, and edges with two equivalent N(2)Sr2Nb2 trigonal pyramids. In the second N site, N(2) is bonded to two equivalent Sr(1) and two equivalent Nb(1) atoms to form NSr2Nb2 trigonal pyramids that share corners with four equivalent N(1)Sr3Nb2 trigonal bipyramids, corners with two equivalent N(2)Sr2Nb2 trigonal pyramids, edges with two equivalent N(1)Sr3Nb2 trigonal bipyramids, and  an edgeedge with one N(2)Sr2Nb2 trigonal pyramid.