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

•Heterodinuclear CuII–DyIII complex•Hexadentate Schiff base ligand•Tautomerism of a Schiff base ligand•Ferromagnetic interactions

A crystal structure of a compartmental ligand N,N′-bis(2,3-dihydroxybenzylidene)-1,3-diaminopropane (H4L = C17H18N2O4) (1) containing N2O2-inner and O4-outer coordination sites and a characterization of its novel diphenoxo-bridged discrete dinuclear complex [CuDy(H2L)(MeOH)(NO3)3]·2MeOH (2) are reported. The Schiff base ligand 1 crystallizes in the orthorhombic P212121 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-amino tautomer is stabilized by intermolecular interactions. The complex 2 crystallizes in the triclinic P-1 space group as a dinuclear compound with CuIIDyIII 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.

Graphical abstractThe structure of N,N′-bis(2,3-dihydroxybenzylidene)-1,3-diaminopropane (H4L = C17H18N2O4) (1) was determined. The keto-enol tautomerism of the hexadentate Schiff base ligand was studied at 100 and 293 K. A new diphenoxo-bridged [CuDy(H2L)(MeOH)(NO3)3]·2MeOH complex (2) that crystallizes in the triclinic P-1 space group was synthesized. In this compound 3d and 4f metal centers are ferromagnetically coupled.Figure optionsDownload full-size imageDownload as PowerPoint slide