Ca4CrN4 crystallizes in the orthorhombic Pnma space group. There are four inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to one N(3), one N(4), two equivalent N(1), and two equivalent N(2) atoms. In the second Ca site, Ca(2) is bonded in a distorted see-saw-like geometry to one N(1), one N(2), and two equivalent N(3) atoms. In the third Ca site, Ca(3) is bonded to one N(2), one N(3), and three equivalent N(4) atoms to form a mixture of distorted corner and edge-sharing CaN5 trigonal bipyramids. In the fourth Ca site, Ca(4) is bonded in a distorted see-saw-like geometry to one N(2), one N(3), and two equivalent N(1) atoms. Cr(1) is bonded in a trigonal planar geometry to one N(1), one N(3), and one N(4) atom. There are four inequivalent N sites. In the first N site, N(4) is bonded in a 5-coordinate geometry to one Ca(1), three equivalent Ca(3), and one Cr(1) atom. In the second N site, N(1) is bonded in a 6-coordinate geometry to one Ca(2), two equivalent Ca(1), two equivalent Ca(4), and one Cr(1) atom. In the third N site, N(2) is bonded to one Ca(2), one Ca(3), one Ca(4), and two equivalent Ca(1) atoms to form NCa5 trigonal bipyramids that share corners with two equivalent N(3)Ca5Cr octahedra, corners with two equivalent N(2)Ca5 trigonal bipyramids, and edges with two equivalent N(3)Ca5Cr octahedra. The corner-sharing octahedral tilt angles range from 51-57°. In the fourth N site, N(3) is bonded to one Ca(1), one Ca(3), one Ca(4), two equivalent Ca(2), and one Cr(1) atom to form distorted NCa5Cr octahedra that share corners with two equivalent N(3)Ca5Cr octahedra, corners with two equivalent N(2)Ca5 trigonal bipyramids, and edges with two equivalent N(2)Ca5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 18°.
Ca4CrN4 crystallizes in the orthorhombic Pnma space group. There are four inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to one N(3), one N(4), two equivalent N(1), and two equivalent N(2) atoms. The Ca(1)-N(3) bond length is 2.54 Å. The Ca(1)-N(4) bond length is 2.45 Å. There is one shorter (2.87 Å) and one longer (2.97 Å) Ca(1)-N(1) bond length. Both Ca(1)-N(2) bond lengths are 2.47 Å. In the second Ca site, Ca(2) is bonded in a distorted see-saw-like geometry to one N(1), one N(2), and two equivalent N(3) atoms. The Ca(2)-N(1) bond length is 2.53 Å. The Ca(2)-N(2) bond length is 2.32 Å. Both Ca(2)-N(3) bond lengths are 2.49 Å. In the third Ca site, Ca(3) is bonded to one N(2), one N(3), and three equivalent N(4) atoms to form a mixture of distorted corner and edge-sharing CaN5 trigonal bipyramids. The Ca(3)-N(2) bond length is 2.39 Å. The Ca(3)-N(3) bond length is 2.52 Å. There are two shorter (2.51 Å) and one longer (2.52 Å) Ca(3)-N(4) bond length. In the fourth Ca site, Ca(4) is bonded in a distorted see-saw-like geometry to one N(2), one N(3), and two equivalent N(1) atoms. The Ca(4)-N(2) bond length is 2.28 Å. The Ca(4)-N(3) bond length is 2.54 Å. Both Ca(4)-N(1) bond lengths are 2.53 Å. Cr(1) is bonded in a trigonal planar geometry to one N(1), one N(3), and one N(4) atom. The Cr(1)-N(1) bond length is 1.72 Å. The Cr(1)-N(3) bond length is 1.75 Å. The Cr(1)-N(4) bond length is 1.69 Å. There are four inequivalent N sites. In the first N site, N(4) is bonded in a 5-coordinate geometry to one Ca(1), three equivalent Ca(3), and one Cr(1) atom. In the second N site, N(1) is bonded in a 6-coordinate geometry to one Ca(2), two equivalent Ca(1), two equivalent Ca(4), and one Cr(1) atom. In the third N site, N(2) is bonded to one Ca(2), one Ca(3), one Ca(4), and two equivalent Ca(1) atoms to form NCa5 trigonal bipyramids that share corners with two equivalent N(3)Ca5Cr octahedra, corners with two equivalent N(2)Ca5 trigonal bipyramids, and edges with two equivalent N(3)Ca5Cr octahedra. The corner-sharing octahedral tilt angles range from 51-57°. In the fourth N site, N(3) is bonded to one Ca(1), one Ca(3), one Ca(4), two equivalent Ca(2), and one Cr(1) atom to form distorted NCa5Cr octahedra that share corners with two equivalent N(3)Ca5Cr octahedra, corners with two equivalent N(2)Ca5 trigonal bipyramids, and edges with two equivalent N(2)Ca5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 18°.