Delocalization of the Unpaired Electron in the Three-Electron Cl-S Bond: ENDOR Study (CROSBI ID 477570)
Prilog sa skupa u zborniku | sažetak izlaganja sa skupa | međunarodna recenzija
Podaci o odgovornosti
Sanković, Krešimir ; Herak, Janko N. ; Hole, Eli O. ; Sagstuen, Einar
engleski
Delocalization of the Unpaired Electron in the Three-Electron Cl-S Bond: ENDOR Study
The "two-centre three-electron" bond found in many activated species (radicals) is usually considered to be strictly localised on the two bonded atoms. Here we show that if one of the atoms participating in the formation of the * bond is a part of a conjugated system, the unpaired electron is delocalised, both via the -bonding (short range) and the -bonding (long range) sub-systems. We studied the interaction of the unpaired electron of the three-electron S-Cl bond in the chlorinated thiocytosine radical with the neighbouring protons by electron-nuclear-double resonance (ENDOR) spectroscopy. The SCl bond is formed on thiocytosine (imbedded in the crystal lattice of cytosine hydrochloride) by acquisition of a chlorine atom that has lost an electron upon ionising irradiation. It is shown that the unpaired electron of the three-electron bond significantly interacts with at least seven protons from its neighbourhood. Five of them have been assigned. From the nature of the coupling tensors it is concluded that three protons are constituents of the chlorine-thiocytosine radical, and the remaining two belong to the neighbouring cytosine molecules. The nature of the dipolar component of the coupling tensors is not consistent with the idea of the location of the entire electron in the SCl bond. From both isotropic and anisotropic tensor components it is concluded that the unpaired electron is significantly delocalised over the radical. It has been estimated that the spin density in the SCl bond is only about 0.4. The data also suggest that we deal with the radical protonated at both N-1 and N-3 positions.
ENDOR; EPR; three-electron bond
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Podaci o prilogu
28 - 28-x.
2000.
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objavljeno
Podaci o matičnoj publikaciji
1999 Europian Conference on Inorganic Mechanisms - Program and Abstracts
Zagreb:
Podaci o skupu
1999 Europian Conference on Inorganic Mechanisms Annual Conference of the Royal Society of Chemistry, Dalton Division Inorganic Reaction Mechanisms Group
poster
06.01.2000-09.01.2000
Zagreb, Hrvatska