Cr2Fe9N8 crystallizes in the monoclinic C2/m space group. Cr(1) is bonded in a distorted trigonal planar geometry to one N(1), one N(2), and one N(3) atom. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a linear geometry to two equivalent N(4) atoms. In the second Fe site, Fe(2) is bonded in a distorted square co-planar geometry to one N(1), one N(2), and two equivalent N(4) atoms. In the third Fe site, Fe(3) is bonded in a distorted see-saw-like geometry to one N(3), one N(4), and two equivalent N(2) atoms. In the fourth Fe site, Fe(4) is bonded to one N(3), two equivalent N(1), and two equivalent N(4) atoms to form a mixture of distorted corner and edge-sharing FeN5 square pyramids. In the fifth Fe site, Fe(5) is bonded in a distorted see-saw-like geometry to one N(1), one N(2), and two equivalent N(3) atoms. There are four inequivalent N sites. In the first N site, N(1) is bonded to one Cr(1), one Fe(2), one Fe(5), and two equivalent Fe(4) atoms to form distorted NCrFe4 trigonal bipyramids that share corners with two equivalent N(4)Fe6 octahedra, corners with two equivalent N(1)CrFe4 trigonal bipyramids, corners with three equivalent N(2)CrFe4 trigonal bipyramids, and edges with two equivalent N(4)Fe6 octahedra. The corner-sharing octahedral tilt angles are 79°. In the second N site, N(2) is bonded to one Cr(1), one Fe(2), one Fe(5), and two equivalent Fe(3) atoms to form distorted NCrFe4 trigonal bipyramids that share corners with two equivalent N(2)CrFe4 trigonal bipyramids, corners with three equivalent N(1)CrFe4 trigonal bipyramids, and edges with two equivalent N(4)Fe6 octahedra. In the third N site, N(3) is bonded in a 5-coordinate geometry to one Cr(1), one Fe(3), one Fe(4), and two equivalent Fe(5) atoms. In the fourth N site, N(4) is bonded to one Fe(1), one Fe(3), two equivalent Fe(2), and two equivalent Fe(4) atoms to form NFe6 octahedra that share corners with three equivalent N(4)Fe6 octahedra, corners with two equivalent N(1)CrFe4 trigonal bipyramids,  an edgeedge with one N(4)Fe6 octahedra, edges with two equivalent N(1)CrFe4 trigonal bipyramids, and edges with two equivalent N(2)CrFe4 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 0-26°.
Cr2Fe9N8 crystallizes in the monoclinic C2/m space group. Cr(1) is bonded in a distorted trigonal planar geometry to one N(1), one N(2), and one N(3) atom. The Cr(1)-N(1) bond length is 1.83 Å. The Cr(1)-N(2) bond length is 1.81 Å. The Cr(1)-N(3) bond length is 1.86 Å. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a linear geometry to two equivalent N(4) atoms. Both Fe(1)-N(4) bond lengths are 1.92 Å. In the second Fe site, Fe(2) is bonded in a distorted square co-planar geometry to one N(1), one N(2), and two equivalent N(4) atoms. The Fe(2)-N(1) bond length is 1.92 Å. The Fe(2)-N(2) bond length is 1.97 Å. Both Fe(2)-N(4) bond lengths are 1.97 Å. In the third Fe site, Fe(3) is bonded in a distorted see-saw-like geometry to one N(3), one N(4), and two equivalent N(2) atoms. The Fe(3)-N(3) bond length is 1.91 Å. The Fe(3)-N(4) bond length is 2.02 Å. Both Fe(3)-N(2) bond lengths are 1.96 Å. In the fourth Fe site, Fe(4) is bonded to one N(3), two equivalent N(1), and two equivalent N(4) atoms to form a mixture of distorted corner and edge-sharing FeN5 square pyramids. The Fe(4)-N(3) bond length is 1.99 Å. Both Fe(4)-N(1) bond lengths are 1.97 Å. There is one shorter (2.00 Å) and one longer (2.08 Å) Fe(4)-N(4) bond length. In the fifth Fe site, Fe(5) is bonded in a distorted see-saw-like geometry to one N(1), one N(2), and two equivalent N(3) atoms. The Fe(5)-N(1) bond length is 1.91 Å. The Fe(5)-N(2) bond length is 1.88 Å. Both Fe(5)-N(3) bond lengths are 1.95 Å. There are four inequivalent N sites. In the first N site, N(1) is bonded to one Cr(1), one Fe(2), one Fe(5), and two equivalent Fe(4) atoms to form distorted NCrFe4 trigonal bipyramids that share corners with two equivalent N(4)Fe6 octahedra, corners with two equivalent N(1)CrFe4 trigonal bipyramids, corners with three equivalent N(2)CrFe4 trigonal bipyramids, and edges with two equivalent N(4)Fe6 octahedra. The corner-sharing octahedral tilt angles are 79°. In the second N site, N(2) is bonded to one Cr(1), one Fe(2), one Fe(5), and two equivalent Fe(3) atoms to form distorted NCrFe4 trigonal bipyramids that share corners with two equivalent N(2)CrFe4 trigonal bipyramids, corners with three equivalent N(1)CrFe4 trigonal bipyramids, and edges with two equivalent N(4)Fe6 octahedra. In the third N site, N(3) is bonded in a 5-coordinate geometry to one Cr(1), one Fe(3), one Fe(4), and two equivalent Fe(5) atoms. In the fourth N site, N(4) is bonded to one Fe(1), one Fe(3), two equivalent Fe(2), and two equivalent Fe(4) atoms to form NFe6 octahedra that share corners with three equivalent N(4)Fe6 octahedra, corners with two equivalent N(1)CrFe4 trigonal bipyramids,  an edgeedge with one N(4)Fe6 octahedra, edges with two equivalent N(1)CrFe4 trigonal bipyramids, and edges with two equivalent N(2)CrFe4 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 0-26°.