Effect of para substituents on magnetic properties of azido-Cu(II) complexes with benzoate/azide coligands: A theoretical perspective

Abstract

The introduction of benzoic acid with different para substituents into the azido-Cu(II) complex can fine-tune the structure of the complex and regulate its magnetic properties. We constructed 22 azido-Cu(II) complexes, optimized their structure at the B3LYP/def2-TZVP level of theory, and studied their magnetic properties at the B3LYP/ZORA-def2-TZVPP level of theory. Results indicate that as the S2 value between non-orthogonal magnetic orbitals gradually increases with the introduction of substituents, the contribution of the antiferromagnetic part to the magnetic coupling constant Jcalc becomes larger, and the Jcalc gradually decreases. We performed spin population analysis and identified two superexchange pathways for these dinuclear complexes and established a relationship between the average Mulliken charge of the carboxylate oxygen atoms and Jcalc. The understanding of the mechanism through which the substituent effect regulates the magnetic properties of complexes provides a theoretical basis for the informed synthesis of azido-Cu(II) complexes.