The Cyanate Ion as Bridging Ligand: Synthesis, Spectroscopic Characterization, and Magnetic Properties of (μ-Cyanato)bis(pentaamminechromium(III)) Chloride

Abstract

The first cyanato-bridged chromium complex and its deuterated analogue have been prepared by thermal decomposition of urea in the presence of CrCl3·6H2O. With the aid of vibrational analysis the bridging has been determined to be end-to-end, including a hitherto unknown Cr-OCN bonding unit. The visible-ultraviolet absorption spectrum can be assigned to single ions in tetragonally distorted environments by using conventional ligand field theory. Magnetic susceptibility data have been interpreted in terms of a weak antiferromagnetic coupling, yielding a value of -0.4 cm-1for the exchange integral J, which corresponds to a singlet-triplet separation of 0.8 cm-1. Considering the various possible exchange pathways, little deviation from linearity in the Cr-NCO-Cr bonding unit is expected. © 1986, American Chemical Society. All rights reserved.