Synthesis, crystal structure, spectroscopic study, and magnetic behavior of the first dinuclear Mn(II) complex of hydrazone-based ligand-containing dicyanamide bridging groups

Abstract

A new dinuclear complex of manganese(II), [Mn(L)(μ_1,5-dca)(CH₃OH)]₂ (1), with dicyanamide anion and (E)-3-hydroxy-N′-(pyridin-2-ylmethylene)-2-naphthohydrazide (HL) was synthesized. The complex was characterized by elemental analyzes, spectroscopic methods, X-ray diffraction, and magnetic susceptibility studies. Two manganese ions in the complex were connected by two bridging dicyanamide ligands in a symmetric end-to-end (μ_1,5-dca) fashion. The presence of intramolecular hydrogen bonding in the mononegative naphthohydrazone (L⁻) affects keto-enol tautomerism and the ligand coordinates to manganese(II) in the keto-form. Magnetic measurements showed an antiferromagnetic interaction between adjacent manganese ions in the dimer.

Keywords:

• Hydrazone ligands
• Dinuclear complex
• X-ray crystal structure
• Manganese complex
• Dicyanamide bridge