Naslov
The nature of multicentre covalent bonding between semiquinone radicals under extreme conditions

Autori
Milašinović, Valentina ; Molčanov, Krešimir ; Zakharov, Boris ; Boldyreva, Elena ; Bogdanov, Nikita

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
17th European Powder Diffraction Conference: Book of Abstracts / - , 2022

Skup
17th European Powder Diffraction Conference (EPDIC17)

Mjesto i datum
Šibenik, Hrvatska, 31.05.2022. - 03.06.2022

Vrsta sudjelovanja
Poster

Vrsta recenzije
Recenziran

Ključne riječi
multicentre bonding ; π-stacking ; charge density

Sažetak
The dominant intermolecular interaction in crystals of organic radicals is π-stacking, which involves some of the closest interplanar and intermolecular C–C contacts (< 3 Å). [1-2] Quantum chemical models indicate a considerable covalent component in the total interaction, and this type of weak multicentre covalent bonding has been dubbed ‘pancake bonding’. [3] Physical properties of crystals, such as magnetism and electric conductivity, are defined by stacking, so its in-depth study is important for understanding and designing radical-based molecular materials with targeted properties. Three types of stacks of planar radicals are known: (1) stacks of 'pancake-bonded' dimers, separated by weaker stacking contacts, (2) stacks of 'pancake-bonded' trimers of partially charged radicals and (3) stacks of equidistant radicals with long-range ordering. [1-2] For this study, three systems of planar radicals were selected: (1) 4-cyano-N-methylpyridinium salt of 5, 6-dichloro- 2, 3-dicyanosemiquinone radical anion as dimers ; (2) 4-dimetilamino-N-methylpyridinium salt of tetrachloro-1, 4-benzoquinone radical anion as trimers and (3) N-methylpyridinium salt of tetrabromo-1, 4-benzoquinone radical anion as stacks of equidistant radicals. The first combined variable-temperature (90 – 400 K) and high-pressure (0.1 MPa – 6.0 GPa) singlecrystal X-ray diffraction study of multicentre bonding (‘pancake bonding’) between planar semiquinone radicals revealed their behaviour under a broad range of conditions. The dimension of a unit-cell, volume and distances between ring planes increased with increasing temperature. High pressure caused the phase transitions and decreased interplanar separations, indicating increased covalent contribution as compared to multicentre bonding at ambient pressure.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA