Open-shell doublet character in a hexaazatrinaphthylene trianion complex.

Area of Science:

• * Inorganic Chemistry
• * Quantum Chemistry
• * Materials Science

Background:

• * Hexaazatrinaphthylene (HAN) is a nitrogen-rich aromatic molecule with unique electronic properties.
• * Electron-deficient aromatic systems are of interest for developing novel molecular materials.
• * Metal-ligand interactions in reduced aromatic systems are crucial for understanding electronic structures.

Purpose of the Study:

• * To synthesize and characterize a novel magnesium complex of a reduced hexaazatrinaphthylene ligand.
• * To investigate the electronic structure and bonding characteristics of the [HAN](3-) ligand in the complex.
• * To explore the potential of such systems as triradicaloid species.

Main Methods:

• * Synthesis of the [(HAN){Mg(nacnac)}3] complex using a magnesium(I) reagent.
• * Spectroscopic and crystallographic characterization of the resulting compound.
• * Ab initio quantum chemical calculations to elucidate the electronic ground state.

Main Results:

• * Successful synthesis of the [(HAN){Mg(nacnac)}3] complex, denoted as compound 1.
• * The [HAN](3-) ligand in compound 1 possesses a spin state of S = 1/2.
• * Ab initio calculations confirmed a multiconfigurational ground-state wave function for the [HAN](3-) ligand, indicative of a triradicaloid nature.

Conclusions:

• * The reduction of HAN with a magnesium(I) reagent yields a stable complex with a highly reduced ligand.
• * The [HAN](3-) ligand exhibits significant triradicaloid character, challenging traditional aromaticity descriptions.
• * This study provides insights into the electronic behavior of reduced polycyclic aromatic nitrogen heterocycles and their metal complexes.