Orbital Angular Momentum Contribution to the Magneto-Optical Behavior of a Binuclear Cobalt(II) Complex

• Published in: Inorganic chemistry 2006-01, Vol.45 (2), p.688-694
• Main Authors: Ostrovsky, S. M, Falk, K, Pelikan, J, Brown, D. A, Tomkowicz, Z, Haase, W
• Format: Article
• Language: English
• Subjects: Circular Dichroism; Cobalt - chemistry; Crystallography, X-Ray; Dimerization; Magnetics; Models, Molecular; Optics and Photonics; Organometallic Compounds - chemistry; Quantum Theory; Temperature
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic0514748

We report magnetic and magnetic circular dichroism investigations of a binuclear Co(II) compound. The Hamiltonian of the system involves an isotropic exchange interaction dealing with the real spins of cobalt(II) ions, spin−orbit coupling, and a low-symmetry crystal field acting within the 4T1g ground manifold of each cobalt ion. It is shown that spin−orbit coupling between this ground term and the low-lying excited ones can be taken into consideration as an effective g factor in the Zeeman part of the Hamiltonian. The value of this g factor is estimated for the averaged experimental values of Racah and cubic ligand field parameters for high-spin cobalt(II). The treatment of the Hamiltonian is performed with the use of a irreducible tensor operator technique. The results of the calculation are in good agreement with experimental observations. Both a large effective g factor for the ground state and a large temperature-independent part of the magnetic susceptibility arise because of a strong orbital contribution to the magnetic behavior of the Co(II) dimer.