Two typical cases of magnetism for dinuclear high-spin cobalt(II) complexes in trigonal-bipyramidal fields

• Published in: Inorganica Chimica Acta 2002-10, Vol.338, p.255-259
• Main Authors: Hossain, Md.Jamil, Sakiyama, Hiroshi
• Format: Article
• Language: English
• Subjects: Dinuclear cobalt(II) complexes; Magnetism; Theoretical method
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/S0020-1693(02)01053-8

Previously, an acyclic ligand 1,3-bis[(2-dimethylaminoethyl)iminomethyl]benzene (baib) was found to form some dinuclear metal complexes [metal=manganese(II), cobalt(II), and zinc(II)], and crystal structures of the two cobalt(II) complexes [Co 2(baib)(MeCO 2) 3]BPh 4 ( 1) and [Co 2(baib)(PhCO 2) 3]BPh 4 ( 2) were determined. Magnetic measurement was also carried out, but the magnetic analysis was not made. In this study, the cryomagnetic data for 1 were analyzed well by using isotropic Heisenberg model with the parameters g=2.30, J=−13.3 cm −1, and Nα=70×10 −6 cm −1, indicating that a ground term does not possess an orbital angular momentum. On the other hand, however, the data for 2 could be interpreted using the so-called Lines’ theory with the parameters λ=−175 cm −1, κ=0.63 and J=−1.0 cm −1, indicating that a ground term possesses an orbital angular momentum. This difference was explained by the fact that the complex cation [Co 2(baib)(PhCO 2) 3] + in 2 was much distorted than [Co 2(baib)(MeCO 2) 3] + in 1, as found by the X-ray analysis. Cryomagnetic data for dinuclear high-spin cobalt(II) complexes 1 and 2 have been analyzed. The data for 1 have been well analyzed by isotropic Heisenberg model, indicating that a ground term does not possess an orbital angular momentum. On the other hand, the data for 2 can be interpreted using Lines’ theory, indicating a ground term possessing an orbital angular momentum.