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Ithas recently been shown that the types of intramolecular magneticinteractions of diradical systems can be changed by the types of radicalgroup: syn-group (or α-group) and anti-group (or β-group).The aim of this study is to establish a useful scheme to understandand explain the intramolecular magnetic interactions in diradicalsystems regardless of radical groups and the topology of a coupler.We investigated the intramolecular magnetic coupling constant (J) of six oxoverdazyl diradicals (i–vi) coupled with a benzene ring based on the unrestrictedDFT calculations. On the basis of our results, we devised a simplebut useful scheme by combining the spin alternation rule and the conceptof radical group classification. Consequently, it was found that thecalculated Jvalues and plots of spin density distributionswere consistent with our proposed scheme. In addition, we discussed the closed-shell singlet (CS) state and the dihedralangle effect on Jvalues in detail to comprehensivelyunderstand the magnetic interactions of diradical systems. Our schemecan provide the basic framework to design future organic high-spinmolecules and organic magnetic materials. [ABSTRACT FROM AUTHOR]

A new series of neutral radicals (DP1–DP6) based on diazaphenalenyl were designed via heteroatomic modifications. As spin sources, the designed radicals were implemented in four different diradical model systems (models I, II, III, and IV) by changing the reference radical and the linkage, and their magnetic interactions between the designed radicals and the reference radical were investigated by using density functional theory calculations. The trend in strength of magnetic interactions of radicals was found to be identical in different model systems. The strength of magnetic interactions could be understood by spin density distributions and NICS values. Our results will be helpful in designing and controlling the organic magnetic materials incorporated with diazaphenalenyl derivatives. In particular, as a new family of spin source radical, DP3could be a potential candidate in designing new organic magnetic materials due to its strong magnetic coupling and high stability in diradical systems. [ABSTRACT FROM AUTHOR]