J Phys Chem A. 2015 Sep 03;119(35):9363-72. doi: 10.1021/acs.jpca.5b05409. Epub 2015 Aug 25.

Fine-Tuning of Magnetic Properties in Nickel(II) Trinuclear EMACs via Modifications of Equatorial Ligands.

The journal of physical chemistry. A

P Szarek, W Grochala

PMID: 26266326 DOI: 10.1021/acs.jpca.5b05409

Abstract

The relationship between equatorial ligands structures and magnetic response of [Ni3]6+ extended metal atom chain core has been investigated. The distances between metal ions in Ni metal strings are largely predefined by framework provided through equatorial ligands. The equatorial ligands thus have primary influence on the magnitude of magnetic coupling between terminal high spin centers. Since the σ channel has greatest contribution to J, the variations in Ni–Ni bond lengths have immediate and strong effect on magnetic properties. The secondary, yet important role is played by ligand field strength and nucleophilicity. It has been shown that energy difference between singly occupied σ-type MOs composed of d(z2) of terminal ions and doubly occupied σ-type MO evolved from d(z2) of the central ion in antiferromagnetic state solution is inversely proportional to magnitude of J. Hence, the alignment between energies of d(z2) orbitals on HS and LS centers directly affected by ligand field strength governs the magnetic response. Moreover, the greater basicity of lone pairs coordinating terminal metal atoms correlates with the larger absolute value of magnetic coupling constant.

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