Crystal and molecular structure and magnetic properties of linear trimeric copper(II) complexes with predominant ferromagnetic exchange interaction

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The crystal and molecular structure of bis(µ-benzoato-O,O′)-bis(benzoato-O)-bis[µ-(2-diethylamino)ethanolato-O,N]-bis(methanol)tricopper(II), (1), has been determined from single-crystal X-ray diffraction data and refined to R= 0.045 using 2 706 independent reflections. The space groups is P; a= 14.793(3), b= 10.533(3), c= 8.127(2)A, α= 73.84(1), β= 84.40(1), γ= 69.15(1)°, and Z= 1. The Cu(1)–Cu(2) distance is 3.188(1)A; the terminal copper atoms are square planar and the central copper is octahedrally co-ordinated. The structure of (1) is compared to that of bis(µ-benzoato-O,O′)-bis(benzoato-O)-bis[µ-(2-dibutylamino)ethanolato-O,N]-bis(ethanol)- tricopper(II), (2), reported previously. The molecular structures show no significant differences; their molecular packings in the crystalline state are discussed. The magnetic moments and susceptibilities of (1) and (2) were measured in the temperature range 5.1–298.6 K and reveal a predominant ferromagnetic exchange interaction. The exchange parameters (H =–2[graphic omitted]JijSiSj) obtained by fit procedures were J12= 30.1 (5.0), J13=–6.1 (3.0) cm–1, g= 2.09(0.02), θ=–1.0(0.5) K for (1) and J12= 28.7(5.0), J13=–7.5(3.0) cm–1, g= 2.09(0.02), θ=–2.3(0.5) K for (2).