1. Generation and Characterization of a Tetraradical Embedded in a Curved Cyclic Paraphenylene Unit.
- Author
-
Miyazawa Y, Wang Z, Hatano S, Takagi R, Matsuoka H, Amamizu N, Kitagawa Y, Kayahara E, Yamago S, and Abe M
- Abstract
Unique spin-spin (magnetic) interactions, ring-size effects on ground-state spin multiplicity, and in-plane aromaticity has been found in localized 1,3-diradicals embedded in curved benzene structures such as cycloparaphenylene (CPP). In this study, we characterized the magnetic interactions in a tetraradical consisting of two localized 1,3-diradical units connected by p-quaterphenyl within a curved CPP skeleton by electron paramagnetic resonance (EPR) spectroscopy and quantum chemical calculations. Persistent triplet species with zero-field splitting parameters similar to those of a triplet 1,3-diphenylcyclopentane-1,3-diyl diradical were observed by continuous wave (CW) or pulsed X-band EPR measurements. The quintet state derived from the ferromagnetic interaction between the two triplet diradical moieties was not detected at 20 K under glassy matrix conditions. At the B3LYP/6-31G(d) level of theory, the singlet state was lower in energy than the triplet and quintet states. These findings will aid in the development of open-shell species for material science application., (© 2023 Wiley-VCH GmbH.)
- Published
- 2023
- Full Text
- View/download PDF