Magnetic interactions in nonalternant mixed molecular radical crystals and mixed ion radical crystals

Abstract

ABSTRACT:The character and the magnitude of magnetic interaction in 1-D stacks of mixed molecular radical crystals (MMRCs) and mixed molecular ion radical crystals (MMIRCs) of alternant aromatic hydrocarbons have already been studied theoretically. In this work nonalternant 1-D stacks built of -electronic subunits are considered. Some of the elementary units are singly or doubly charged (MMIRCs), others are neutral (MMRCs); alternant and nonalternant subunits are used as building blocks. Qualitative investigations based on the band theory of exchange effects in solid organic open-shell systems are carried out. The contributions to the effective exchange integral J eff : direct (Hund's), kinetic and indirect, are calculated. Structures of 1:1 MMRCs and MMIRCs with positive value of the integral J eff , accounting for the spin exchange of the electrons in the half-filled band, i.e., with ferromagnetic ground state, are suggested. The influence of different parameters (molecular size, presence of heteroatoms, localization versus delocalization, alternant versus nonalternant, charge, etc.) on the magnitude of the net exchange is discussed.

The Role of Orbital Symmetries in Enforcing Ferromagnetic Ground State in Mixed Radical Dimers

“…However, the results herein can also be applied to other p-block radical frameworks. To the best of our knowledge, quantitative theoretical studies on real-world radical pairs with mixed orbital symmetries have not been published before, although the importance of the nodal properties of SOMOs has been noted, and various systems composed of neutral organic radicals and diamagnetic spacers have been thoroughly investigated. − …”