Materials Data on Cr3N2 by Materials Project

Abstract

Cr3N2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are five inequivalent Cr2+ sites. In the first Cr2+ site, Cr2+ is bonded to five N3- atoms to form distorted CrN5 trigonal bipyramids that share corners with five equivalent CrN4 tetrahedra, an edgeedge with one CrN4 tetrahedra, and edges with two equivalent CrN5 trigonal bipyramids. There are a spread of Cr–N bond distances ranging from 2.02–2.07 Å. In the second Cr2+ site, Cr2+ is bonded to four N3- atoms to form distorted CrN4 tetrahedra that share corners with two equivalent CrN4 tetrahedra, corners with five equivalent CrN5 trigonal bipyramids, edges with two equivalent CrN4 tetrahedra, and an edgeedge with one CrN5 trigonal bipyramid. There are two shorter (1.96 Å) and two longer (2.04 Å) Cr–N bond lengths. In the third Cr2+ site, Cr2+ is bonded in a 3-coordinate geometry to three N3- atoms. There is two shorter (1.96 Å) and one longer (1.97 Å) Cr–N bond length. In the fourth Cr2+ site, Cr2+ is bonded in a rectangular see-saw-like geometry to four N3- atoms. There are a spread of Cr–N bond distances ranging from 1.92–2.13 Å. In the fifth Cr2+ site, Cr2+ is bonded in a square co-planar geometry to four equivalent N3- atoms. All Cr–N bond lengths are 1.97 Å. There are three inequivalent N3- sites. In the first N3- site, N3- is bonded in a 6-coordinate geometry to six Cr2+ atoms. In the second N3- site, N3- is bonded to six Cr2+ atoms to form a mixture of distorted corner and edge-sharing NCr6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 50–64°. In the third N3- site, N3- is bonded to six Cr2+ atoms to form a mixture of corner and edge-sharing NCr6 octahedra. The corner-sharing octahedral tilt angles are 0°.