Naslov
Stabilisation of tetrabromo- and tetrachlorosemiquinone (bromanil and chloranil) anion radicals in crystals

Autori
Molčanov, Krešimir ; Kojić-Prodić, Biserka ; Babić, Darko ; Žilić, Dijana ; Rakvin, Boris

Izvornik
Crystengcomm (1466-8033) 13 (2011), 16; 5170-5178

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
semiquinone radical anion; tetrachlorosemiquinone; chloranil; tetrabromosemiquinone; bromanil; crystal structures; π•••π stacking; radical anion dimers; antiferromagnetic coupling; magnetic properties; EPR

Sažetak
Crystal structures of alkali salts of tetrahaolgenosemiquinone anion radical acetone solvates and their solvent-free salts are determined. p-Semiquinone anion radical reveals enhanced aromaticity of the ring compared to the quinone. A pair of π-stacked radical anion (p-semiquinone) rings occurs in crystal structures of potassium and rubidium salts of tetrachlorosemiquinone anion acetone solvates and their potassium tetrabromo analogue. The ring centroid separation distances are about 3.2 Å and carbon-carbon contacts between the contiguous rings are 0.3 Å shorter than the sum of van der Waals radii. The spin-coupling of the two unpaired electrons between the two anion radical rings (forming a stacked dimer) correlates with diamagnetic property of crystals. Magnetic properties of alkali salts of tetrahaolgenosemiquinone anion radical acetone solvates were examined by electron paramagnetic resonance spectroscopy.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA