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Université de Fribourg

Electronic structure and absorption spectra of biferrocenyl and bisfulvalenide diiron radical cations: detection and assignment of new low-energy transitions

Warratz, Ralf ; Aboulfadl, Hanane ; Bally, Thomas ; Tuczek, Felix

In: Chemistry - A European Journal, 2009, vol. 15, no. 7, p. 1604 - 1617

Low-energy electronic transitions have been detected spectroscopically in the FeII-FeIII mixed-valent biferrocenyl radical cation, but are absent in the spectra of the neutral analogue. They have been assigned by time-dependent DFT calculations (squares in figure). Analogous investigations were performed for the bisfulvalenide FeII-FeIII radical cation....

Université de Fribourg

Ultrafast Spectroscopic and Matrix Isolation Studies of p-Biphenylyl, o-Biphenylyl, and 1-Naphthylnitrenium Cations

Wang, Jin ; Burdzinski, Gotard ; Zhu, Zhendong ; Platz, Matthew S. ; Carra, Claudio ; Bally, Thomas

In: Journal of the American Chemical Society, 2007, vol. 129, no. 26, p. 8380-8388

p-Biphenylyl, o-biphenylyl, and 1-naphthyl azides were deposited in argon at low temperature in the presence and absence of HCl. In the absence of HCl, the known electronic and vibrational spectra of the corresponding triplet nitrenes, azirines, and didehydroazepines were observed, whereas in the presence of HCl, photolysis of these azides produces new electronic spectra assigned to...

Université de Fribourg

Photochemistry of reactive intermediates

Bally, Thomas

In: Chimia, 2007, vol. 61, no. 10, p. 645-649

This paper illustrates the research on the photochemistry of reactive intermediates that was (and still is) carried out in the author's research group on three typical examples: the photochemistry of arylcarbenes, arylnitrenes, and organic radical cations.

Université de Fribourg

Matrix isolation and computational study of the photochemistry of 1,3,2,4-Benzodithiadiazine

Gritsan, Nina P. ; Pritchina, Elena A. ; Bally, Thomas ; Makarov, Alexander Yu. ; Zibarev, Andrey V.

In: The Journal of Physical Chemistry A, 2007, vol. 111, no. 5, p. 817 -824

Photolysis of 1,3,2,4-benzodithiadiazine (1) at ambient temperature yields stable 1,2,3-benzodithiazolyl radicals. In order to reveal the mechanism of this unusual transformation, the photochemistry of 1 was studied in argon matrices using IR and UV-vis spectroscopy. A series of intermediates, including four- and five-membered heterocyclic and o-quinoid acyclic species, were characterized...

Université de Fribourg

Mechanistic aspects of the oxidative and reductive fragmentation of n-nitrosoamines: a new method for generating nitrenium cations, amide anions, and aminyl radicals

Piech, Krzysztof ; Bally, Thomas ; Sikora, Adam ; Marcinek, Andrzej

In: Journal of the American Chemical Society, 2007, vol. 129, no. 11, p. 3211 -3217

A new method for investigating the mechanisms of nitric oxide release from NO donors under oxidative and reductive conditions is presented. Based on the fragmentation of N-nitrosoamines, it allows generation and spectroscopic characterization of nitrenium cations, amide anions, and aminyl radicals. X-irradiation of N-nitroso-N,N-diphenylamine 1 in Ar matrices at...

Université de Fribourg

The Dewar benzene radical cation and tts ring-opening reaction

Bally, Thomas ; Matzinger, Stephan ; Bednarek, Pawel

In: Journal of the American Chemical Society, 2006, vol. 128, no. 24, p. 7828 -7834

Université de Fribourg

Calculations of the optical spectra of hydrocarbon radical cations based on Koopmans' theorem

Nelsen, Stephen F. ; Weaver, Michael N. ; Yamazaki, Daisuke ; Komatsu, Koichi ; Rathore, Rajendra ; Bally, Thomas

In: The Journal of Physical Chemistry A, 2007, vol. 111, no. 9, p. 1667 -1676

The first few bands in the optical spectra of radical cations can often be interpreted in terms of A-type transitions that involve electron promotions from doubly occupied to the singly occupied molecular orbital (SOMO) and/or B-type transition which involve electron promotion from the SOMO to virtual molecular orbitals. We had previously demonstrated that, by making use of Koopmans' theorem, the...

Université de Fribourg

Cyclobutadiene : the antiaromatic paradigm ?

Bally, Thomas

In: Angewandte Chemie International Edition, 2006, vol. 45, no. 40, p. 6616 - 6619

Université de Fribourg

Radical Cations of Phenyl-Substituted Aziridines: What Are the Conditions for Ring Opening ?

Gaebert, Carsten ; Mattay, Jochen ; Toubartz, Marion ; Steenken, Steen ; Müller, Beat ; Bally, Thomas

In: Chemistry - A European Journal, 2005, vol. 11(4), p. 1294-1304

Radical cations were generated from different phenyl-substituted aziridines by pulse radiolysis in aqueous solution containing TlOH.+, N₃. or SO₄.- as oxidants or in n-butyl chloride, by ⁶⁰Co γ radiolysis in Freon matrices at 77 K, and in some cases by flash photolysis in aqueous solution. Depending on the substitution pattern of the aziridines, two...