Synthesis and magnetic properties of new nickel(II)-copper(II)-nickel(II) trinuclear complexes with irregular spin-state structure |
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Authors: | Ming-Ming Miao Dai-Zheng Liao Zong-Hui Jiang Geng-Lin Wang |
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Affiliation: | (1) Department of Chemistry, Nankai University, Tianjin, P.R. China |
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Abstract: | Summary Four novel heterotrinuclear complexes were prepared, namely {[Ni(L)2]2[Cu(pba)]}(ClO4)2, where pba = pro-pylene-1,3-bis(oxamato) and L = 1,10-phenanthroline (phen), 5-nitro-1,10-phenanthroline (NO2-phen), 2,2-bipyridyl (bpy), 4,4-dimethyl-2,2-bipyridyl (Me2bpy). Based on i.r., elemental analyses, conductivity measurements and electronic spectra oxamato-bridged structures are proposed for these complexes, consisting of two nickel(II) ions, each in a distorted octahedral environment, and a copper(II) ion in a square planar environment, respectively. The temperature dependence of the magnetic susceptibility of {[Ni(phen)2]2[Cu(pba)]}(ClO4)2·H2O was studied in the 4–300 K range, giving the exchange integral J = - 106 cm–1. TheXscmT versusT plot exhibited a minimum at ca. 98 K, characteristic of this kind of coupled polymetallic complex with an irregular spin-state structure. E.s.r. spectra of these complexes clearly indicated a strong rhombicity withg1 = 5.20,g2 = 2.29 andg3 = 2.02 (approximately), which agrees with an anisotropicS = ±1/2 Kramer doublet in the ground state. |
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