Influence of Ligand-Bridged Substitution on the Exchange Coupling Constant of Chromium-Wheels Host Complexes: A Density Functional Theory Study Publisher



Sadeghi Googheri M¹ ; Abolhassani MR¹ ; Mirzaei M²
Source: Molecular Physics Published:2018

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(tBuCO2)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 J values became more positive. In the case of hydroxo-bridged model [Cr2OH(tBuCO2)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 J value 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. © 2018 Informa UK Limited, trading as Taylor & Francis Group.