Tautomerism of a compartmental Schiff base ligand and characterization of a new heterometallic CuII-DyIII complex - Synthesis, structure and magnetic properties

A crystal structure of a compartmental ligand N,N'-bis(2,3-dihydroxybenzylidene)-1,3-diaminopropane (H4L = C17H18N2O4) (1) containing N2O2-inner and O-4-outer coordination sites and a characterization of its novel diphenoxo-bridged discrete dinuclear complex [CuDy(H2L)(MeOH)(NO3)(3)]center dot 2MeOH (2) are reported. The Schiff base ligand 1 crystallizes in the orthorhombic P2(1)2(1)2(1) space group with a molecule in a bent conformation. The compound at 100 and 293 K displays the keto-enol tautomerism with the equilibrium in both temperatures shifted with a different degree towards the zwitterionic keto-amino form. The quantum chemical calculations showed preferences for enol-imino form in a gas phase and for keto-amine in solutions. The keto-aminotautomer is stabilized by intermolecular interactions. The complex 2 crystallizes in the triclinic P-1 space group as a dinuclear compound with cu(II)Dy(III) core. The Dy(III) ion is nine-coordinated whereas the coordination number of Cu(II) is five. The temperature dependence of the magnetic susceptibility and the field-dependent magnetization indicated that the interaction between Cu(II) and Dy(III) metal centers in 2 is ferromagnetic. (C) 2014 Elsevier B.V. All rights reserved.