Influence of ligand-bridged substitution on the exchange coupling constant of chromium-wheels host complexes: a density functional theory study

Abstract

Designing and introducing novel wheel-shaped supramolecular as host complexes with new magnetic properties is the theme of the day. So in this study, new eight binuclear chromium (III) complexes, as models of real chromium-wheel host complexes, were designed based on changing of bridged-ligands and exchange coupling constants (J) of them were calculated using the broken symmetry density functional theory approach. Substitution of fluorine ligand in fluoro-bridged model Cr2F(tBuCO(2))(2)(H2O)(2)(OH)(4)(-1) by halogen anions (Cl-, Br- and I- ) decreased the antiferromagnetic exchange coupling between Cr(III) centres such that by going from F- to I- the Jvalues became more positive. In the case of hydroxo-bridged model Cr2OH(tBuCO(2))(2)(H2O)(2)(OH)(4)(-1), replacement of hydroxyl by methoxy anion (OMe-) strengthened the antiferromagnetic property of the complex but substitution by sulfanide (SH-) and amide (NH2-) anions weakened it and changed the nature of complexes to ferromagnetic. Because of their different magnetic properties, these new investigated complexes can be suggested as interesting synthetic targets. Also, the Jvalue changes due to ligand substitution were evaluated and it was found that the Cr-X bond strength and partial charges of involved atoms were the most effective factors on it. GRAPHICS .