Experimental and theoretical studies on ferromagnetically coupled metal complexes with imino nitroxides

Area of Science:

• Coordination Chemistry
• Inorganic Chemistry
• Materials Science

Background:

• Imino nitroxyl diradicals are organic molecules with unpaired electrons.
• These diradicals can coordinate with metal ions to form complexes.
• Understanding the magnetic properties of such complexes is crucial for developing new magnetic materials.

Purpose of the Study:

• To synthesize and characterize novel Copper(II), Zinc(II), and Nickel(II) complexes with an imino nitroxyl diradical ligand (bisimpy).
• To investigate the magnetic properties, including magnetic coupling, of these metal complexes.
• To elucidate the coordination geometries and electronic structures of the synthesized complexes using experimental and computational methods.

Main Methods:

• Synthesis of Copper(II), Zinc(II), and Nickel(II) complexes with the bisimpy ligand.
• X-ray crystallography to determine the coordination geometry of the metal ions.
• Magnetic susceptibility measurements to study magnetic interactions.
• Electron Paramagnetic Resonance (EPR) spectroscopy to probe electronic properties.
• Density Functional Theory (DFT) calculations for spin density distribution analysis.

Main Results:

• Three metal complexes, [CuCl(bisimpy)(MeOH)](PF6) (1), [ZnCl2(bisimpy)] (2), and [NiCl(bisimpy)(H2O)2]Cl x 2H2O (3), were successfully prepared.
• Complexes 1 and 3 exhibited ferromagnetic coupling between the metal ions and the imino nitroxyl diradicals, with coupling constants J = +165(1) cm⁻¹ for Cu(II) and J = +109(2) cm⁻¹ for Ni(II).
• Intraligand ferromagnetic interactions were found to be very weak in all studied complexes.

Conclusions:

• The study successfully synthesized and characterized novel metal-bisimpy complexes.
• Ferromagnetic coupling was confirmed in Copper(II) and Nickel(II) complexes, indicating potential for magnetic materials development.
• DFT calculations provided insights into the spin density distribution, complementing experimental magnetic data.