Neutral Antiaromatic Bis(1,2-dithiolene)-Chelated Nickel Complexes Bearing Multiradical Characters

Area of Science:

• Coordination Chemistry
• Materials Science
• Theoretical Chemistry

Background:

• Metal-organic complexes with radical characteristics are gaining attention for unique properties.
• Existing complexes rarely exceed diradicality, limiting their potential applications.

Purpose of the Study:

• To systematically investigate multiradical properties in square planar neutral Ni-bis(1,2-dithiolene) and Ni-bis(1,2-dioxolene) complexes.
• To explore the influence of linear, branched, and macrocyclic configurations on radical character.
• To understand the design principles for novel multiradical antiaromatic macrocyclic complexes.

Main Methods:

• Utilizing ab initio calculations to study electronic structures.
• Analyzing Ni-bis(1,2-dithiolene) and Ni-bis(1,2-dioxolene) complexes.
• Investigating linear, branched, and macrocyclic structural motifs.

Main Results:

• Linear Ni-complexes exhibit strong singlet diradical character.
• Branched Ni-complexes show moderate singlet multiradical character.
• Macrocyclic Ni-complexes demonstrate extremely strong singlet multiradical characters (up to dodeca-radicality) and global antiaromaticity.
• Antiaromaticity in macrocycles leads to strong induced ring currents under magnetic fields due to localized unpaired electrons.

Conclusions:

• The study presents the first rational design of novel multiradical neutral antiaromatic macrocyclic complexes.
• These complexes possess unique electronic properties arising from electron localization.
• Potential applications in molecular machines and electronic devices are highlighted.