Magnetic analyses of isosceles tricobalt(II) complexes containing two types of octahedral high-spin cobalt(II) ions

Hiroshi Sakiyama, Harry Adams, David E. Fenton, Laura R. Cummings, Paul E. McHugh, Hisashi Okawa

.

DOI: 10.4236/ojic.2011.13005                

Abstract

The observed magnetic data for two isosceles tricobalt(II) complexes have been successfully analyzed, considering the axial distortion around each cobalt(II) ion, the local spin-orbit coupling, the anisotropic exchange interactions, and the intermolecular exchange interactions. The complexes each contains two types of octahedral high-spin cobalt(II) ions (Co_A and Co_B) in the shape of an isosceles triangle (Co_A1–Co_B–Co_A2), and the contribution of the orbital angular momentum is significant. The exchange interaction between the Co_A and Co_B ions is practically negligible (J = ~ 0), whereas the interaction between the Co_A1 and Co_A2 ions is ferromagnetic (J’ > 0) for both complexes.

Keywords

Tricobalt(II) Complex; Magnetic Properties; Spin-Orbit Coupling; Exchange Interaction

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Kahn, O. (1993) Molecular magnetism. VCH Publishers, New York.
[2]	Lines, M.E. (1963) Magnetic properties of CoCl2 and NiCl2. Physical Review, 131, 546-555. doi:10.1103/PhysRev.131.546
[3]	Figgis, B.N., Gerloch, M., Lewis, J., Mabbs, F.E. and Webb, G.A. (1968) The magnetic behaviour of cubic-field 4T1g terms in lower symmetry. Journal of Chemical Society A, 1, 2086-2093. doi:10.1039/j19680002086
[4]	Lines, M.E. (1971) Orbital angular momentum in the theory of paramagnetic clusters. Journal of Chemical Physics, 55, 2977-2984. doi:10.1063/1.1676524
[5]	Sakiyama, H., Ito, R., Kumagai, H., Inoue, K., Saka- moto, M., Nishida, Y. and Yamasaki, M. (2001) Dinuclear cobalt(II) complexes of an acyclic phenol-based dinucle- ating ligand with four methoxyethyl chelating arms— First magnetic analyses in an axially distorted octahedral field. European Journal of Inorganic Chemistry, 2001, 2027-2032.
[6]	Sakiyama, H. (2001) Development of magsaki(A) software for the magnetic analysis of dinuclear high-spin cobalt(II) complexes considering anisotropy in exchange interaction. Journal of Chemical Software, 7, 171-178. doi:10.2477/jchemsoft.7.171
[7]	Hossain, M.J., Yamasaki, M., Mikuriya, M., Kuribayashi, A. and Sakiyama, H. (2002) Synthesis, structure, and magnetic properties of dinuclear cobalt(II) complexes with a new phenol-based dinucleating ligand with four hydroxyethyl chelating arms. Inorganic Chemistry, 41, 4058-4062. doi:10.1021/ic0255297
[8]	Sakiyama, H. (2006) Magnetic susceptibility equation for dinuclear high-spin cobalt(II) complexes considering the exchange interaction between two axially distorted octahedral cobalt(II) ions. Inorganica Chimica Acta, 359, 2097-2100. doi:10.1016/j.ica.2005.12.052
[9]	Sakiyama, H. (2007) Magnetic susceptibility equation for dinuclear high-spin cobalt(II) complexes considering the ex- change interaction between two axially distorted octahedral cobalt(II) ions. Inorganica Chimica Acta, 360, 715-716. doi:10.1016/j.ica.2006.06.011
[10]	Tone, K., Sakiyama, H., Mikuriya, M., Yamasaki, M. and Nishida, Y. (2007) Magnetic behavior of dinuclear co- balt(II) complexes assumed to be caused by a paramag- netic impurity can be explained by tilts of local distortion axes. Inorganic Chemistry Communications, 10, 944-947. doi:10.1016/j.inoche.2007.04.028
[11]	Palii, A.V., Tsukerblat, B.S., Coronado, E., Clemente- Juan, J.M. and Borras-Almenar, J.J. (2003) Microscopic approach to the pseudo-spin-1/2 Hamiltonian for Kramers doublets in exchange coupled Co(II) pairs. Inorganic Chemistry, 42, 2455-2458. doi:10.1021/ic0259686
[12]	Palii, A.V., Tsukerblat, B.S., Coronado, E., Clemente- Juan, J.M. and BorrasAlmenar, J.J. (2003) Orbitally dependent magnetic coupling between cobalt(II) ions: The problem of the magnetic anisotropy. The Journal of Chemical Physics, 118, 5566-5581. doi:10.1063/1.1555122
[13]	Palii, A.V., Tsukerblat, B.S., Coronado, E., Clemente- Juan, J.M. and Borras-Almenar, J.J. (2003) Orbitally dependent kinetic exchange in cobalt(II) pairs: Origin of the magnetic anisotropy. Polyhedron, 22, 2537-2544. doi:10.1016/S0277-5387(03)00207-9
[14]	Lloret, F., Julve, M. Cano, J., Ruiz-García, R. and Pardo, E. (2008) Magnetic properties of six-coordinated high- spin cobalt(II) complexes: Theoretical background and its application. Inorganica Chimica Acta, 361, 3432-3445. doi:10.1016/j.ica.2008.03.114
[15]	Adams, H., Fenton, D.E., Cummings, L.R., McHugh, P.E., Ohba, M., Okawa, H., Sakiyama, H. and Shiga, T. (2004) The structures and magnetism of trinuclear Ni(II), Co(II) and Mn(II) complexes derived from unsymmetrical com- partmental ligands. Inorganica Chimica Acta, 357, 3648- 3656. doi:10.1016/j.ica.2004.03.055
[16]	Scaringe, R.P., Hodgson, D.J. and Hatfield, W.E. (1978) The coupled representation matrix of the pair hamiltonian. Molecular Physics, 35, 701-713. doi:10.1080/00268977800100521
[17]	Low, W. (1958) Paramagnetic and optical spectra of divalent cobalt in cubic crystalline fields. Physical Review, 109, 256-265. doi:10.1103/PhysRev.109.256
[18]	Figgis B.N. and Hitchman, M.A. (2000) Ligand field theory and its application. Wiley-VCH, New York.