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Monomeric and dimeric copper(II) complexes composed of some terdentate Schiff bases and oxalate, oxamate, azide, thiocyanate or cyanate ions

1983; Elsevier BV; Volume: 74; Linguagem: Inglês

10.1016/s0020-1693(00)81423-1

1873-3255

Yasuo Nakao, Mitsuhiro Yamazaki, Shinnichiro Suzuki, Wasuke Mori, Akitsugu Nakahara, K. Matsumoto, Shun′ichiro Ooi,

Magnetism in coordination complexes

Monomeric and dimeric copper(II) complexes containing the Schiff bases derived from 2-pyridinecarbaldehyde and histamine (2-PcaHist), 2-(2-aminoethyl)pyridine (2-Pca2-Aep), or β-alanine (2-Pcaβ-Ala), and oxalate (ox), oxamate (om), azide, thiocyanate, or cyanate ions have been prepared and characterized based on their electronic, infrared and electron spin resonance spectra, and magnetic susceptibilities. The structure of the monomeric copper(II) complex, [Cu(2-PcaHist)(N3)2] has been determined by the X-ray diffraction method. The crystal of [Cu(2-PcaHist)(N3)2] is triclinic, with a = 10.262(8), b = 9.177(6), c = 7.688(5) Å, α = 104.42(4), β = 94.09(4), γ = 92.64(4)°, Z = 2, and space group P1. The five-coordinate geometry around copper(II) ion is intermediate between trigonal-bipyramid and square-pyramid. The half-field absorption in the ΔMs = 2 region of powdered X-band ESR spectra was scarcely observed for [Cu(2-Pca2-Aep)(N3)2], [Cu(2-Pca2-Aep)(NCS)2], [Cu(2-Pca2-Aep)(NCO)2] and [Cu(2-PcaHist(N3)2]. The compounds [Cu2(2-PcaHist)2(N3)3]Cl·2H2O and [Cu2(2-PcaHist)2(N3)2](ClO4)2 which are considered to have a dimeric structure exhibited the half-field absorption in the same region. However, an exchange interaction was hardly observed down to 4.2 °K in the magnetic susceptibility measurement for [Cu2(2-PcaHist)2(N3)3](Cl·2H2O. The susceptibility of an oxalate-bridged copper(II) complex, [Cu2(2-PcaHist)2(ox)](ClO4)2, showed an antiferromagnetic interaction (J = −21.5 cm−1) and the X-band ESR spectrum for the powdered sample showed a very weak absorption for the triplet state of such a dimer in the ΔMs = 2 region.