Counter-rotating spin-polarised ring currents in odd-electron carbocycles

Area of Science:

• Quantum Chemistry
• Theoretical Chemistry
• Organic Chemistry

Background:

• Understanding magnetic response in organic molecules is crucial.
• Electron spin's role in magnetic phenomena is complex.
• Carbocycles with odd π-electron systems present unique electronic properties.

Purpose of the Study:

• To propose a molecular-orbital model for magnetic-field-induced ring currents in odd π-electron carbocycles.
• To explain the role of majority and minority spins in sustaining these currents.
• To validate the model using computational chemistry methods.

Main Methods:

• Development of a molecular-orbital model based on the ipsocentric approach.
• Utilizing frontier-orbital contributions and angular-momentum selection rules.
• Performing coupled unrestricted Hartree-Fock (UHF) ab initio calculations.
• Comparing results with correlated MP2 spin-polarized current calculations.

Main Results:

• The proposed model successfully explains counter-rotating ring currents in odd π-electron carbocycles.
• Majority and minority spins were shown to be key drivers of these currents.
• Ab initio calculations confirmed the model's predictions for benzene and cyclo-octatetraene ions.
• Results align with more advanced correlated spin-polarized calculations.

Conclusions:

• The molecular-orbital model provides a robust framework for understanding spin-dependent magnetic responses in carbocycles.
• Frontier orbitals and spin polarization are critical factors in magnetic-field-induced ring currents.
• The findings offer insights into the electronic behavior of charged organic systems under magnetic fields.