Charge density of the semiquinone radical anion (CROSBI ID 640726)
Prilog sa skupa u časopisu | sažetak izlaganja sa skupa | međunarodna recenzija
Podaci o odgovornosti
Molčanov, Krešimir ; Jelsch, Christian ; Wenger, Emmanuel ; Stilinović, Vladimir ; Kojić-Prodić, Biserka
engleski
Charge density of the semiquinone radical anion
Semiquinones are a class of stable organic radical anions ; especially stable are ones with four electronegative substituents such as halogens, which enhance delocalisation of the unpaired electron. Therefore, they are potential candidates for design of functional materials with fine-tuned magnetic properties. Here we present detalied study of electron density and delocalisation in two polymorphs of N-methylpyridinium salt of the tetrachlorosemiquinone radical anion (N- MePy∙CA), which are especially interesting due to their stability and semiconductivity. In the diamagnetic polymorph closely bound radical dimers occur, similar to previously known K∙CA∙Me2CO and similar alkali salts of 5, 6- dichloro-2, 3-dicyanosemiquinone (DDQ), and the crystals are diamagnetic due to spin pairing. In the orthorhombic polymorph radicals are equdistant, leading to 1D antiferromagnetic coupling between the spins. Electronic delocalisation in the semiquinones is particulary interesting because it is somewhere between aromatic (fully delocalised π electrons) and quinoid (distinguishable single and double bonds), as confirmed by previous crystallographic and computational studies. However, exact bond orders of C-C and C-O bonds have not yet been experimentally determined. Also, study of charge density reveals subtle differences between diamagnetic (triclinic) and antiferromagnetic (orthorhombic) phases, which will enable more insight into the phenomenon of magnetic exchange between organic molecules. This is the first experimental study of electronic structure in ionic semiquinones, and is complemented by periodic DFT caculations.
semiquinone ; electronic structure ; charge density
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Podaci o prilogu
s90-s90.
2016.
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objavljeno
Podaci o matičnoj publikaciji
Acta crystallographica. Section A, Foundations and advances
Fromm, Katharina
Basel: European Crystallographic Association
2053-2733
Podaci o skupu
30th European Crystallographic Meeting
predavanje
28.08.2016-01.09.2016
Basel, Švicarska