### Abstract

A purposefully synthesized nitroxide biradical R_{6}-p-C_{6}H_{4}-R_{6} (B1), where R_{6} is the 1-oxyl-2,2,6,6-tetramethyl-1,2,5,6-tetrahydropyridine group with a relatively short distance between the two radical sites, has been studied by X-band electron paramagnetic resonance (EPR) spectroscopy. Hyperfine splitting (hfs) constants on the ^{14}N atoms, electron spin exchange integral |J|, and the distance between the two N–O fragments r_{NO–NO} were experimentally measured. Density functional theory, DFT, calculations were performed using the ORCA 4.0.1.2 program package. The optimized geometry was compared with X-ray crystallographic data and theoretical hfs constants were compared with the respective experimental EPR values. It is concluded that the current quantum chemical approaches provide good results in calculating hfs constants as well as some other EPR parameters. It is confirmed that the intramolecular electron spin exchange in biradicals analogous to B1 is realized by the indirect mechanism rather than direct collision of the N–O· groups. It is also shown that one can calculate and predict values of |J| in other similar biradicals based on the principle of “attenuation coefficients.

Original language | English |
---|---|

Pages (from-to) | 425-439 |

Number of pages | 15 |

Journal | Applied Magnetic Resonance |

Volume | 50 |

Issue number | 1-3 |

DOIs | |

Publication status | Published - Mar 1 2019 |

### ASJC Scopus subject areas

- Atomic and Molecular Physics, and Optics

## Fingerprint Dive into the research topics of 'The Structure and Internal Dynamics of R<sub>6</sub>-p-C<sub>6</sub>H<sub>4</sub>-R<sub>6</sub> Biradical: EPR, X-ray Crystallography and DFT Calculations'. Together they form a unique fingerprint.

## Cite this

_{6}-p-C

_{6}H

_{4}-R

_{6}Biradical: EPR, X-ray Crystallography and DFT Calculations.

*Applied Magnetic Resonance*,

*50*(1-3), 425-439. https://doi.org/10.1007/s00723-018-1089-8