Crystal structure of hexakis(urea-κ<i>O</i>)chromium(III) dichromate bromide monohydrate from synchrotron X-ray data

Abstract

The title bromide salt, [Cr{CO(NH2)2}6](Cr2O7)Br·H2O, is isotypic to the corresponding chloride salt. Within the complex cation, the Cr(III) atom is coordinated by six O atoms of six urea ligands, displaying a slightly distorted octa-hedral coordination environment. The Cr-O bond lengths involving the urea ligands are in the range 1.9534 (13)-1.9776 (12) Å. The Cr2O7 (2-) anion has a nearly staggered conformation, with a bridging angle of 130.26 (10)°. The individual components are arranged in rows extending parallel to [100]. The Br(-) anion links the complex cation, as well as the solvent water mol-ecule, through N-H⋯Br and O-H⋯Br hydrogen-bonding inter-actions. The supra-molecular architecture also includes N-H⋯O and O-H⋯O hydrogen bonding between urea N-H and water O-H donor groups and the O atoms of the Cr2O7 (2-) anion as acceptor atoms, leading to a three-dimensional network structure.