Ergebnisse einschränken

Dokumententyp

Institution

Spezialsammlung

Sprache

Université de Fribourg

Synthesis and structure of m-terphenyl thio-, seleno-, and telluroethers

Zakai, Uzma I. ; Błoch-Mechkour, Anna ; Jacobsen, Neil E. ; Abrell, Leif ; Lin, Guangxin ; Nichol, Gary S. ; Bally, Thomas ; Glass, Richard S.

In: Journal of Organic Chemistry, 2011, vol. 75, no. 24, p. 8363–8371

Several routes for the synthesis of m-terphenyl thio-, seleno-, and telluroethers were investigated. m-Terphenyl iodides react with diphenyl diselenides or ditellurides (CsOH·H₂O, DMSO, 110 °C) to give the desired compounds in 19−84% yield which significantly extends the previously reported such reactions because o-benzyne cannot be an intermediate as previously...

Université de Fribourg

Synthesis and rotation barriers in 2, 6-Di-(o-anisyl) anisole

Yamamoto, Takuhei ; Chen, Pi-Yu ; Lin, Guangxin ; Błoch-Mechkour, Anna ; Jacobsen, Neil E. ; Bally, Thomas ; Glass, Richard S.

In: Journal of Physical Organic Chemistry, 2012, p. -

Variable temperature ¹H NMR spectroscopic studies of 2, 6-di(o-anisyl) anisole show syn and anti atropisomers at low temperature. The barrier for interconverting these isomers by rotation about the aryl-aryl bond, found by fitting the experimental data, is 41.2 kJ/mol.

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

One-pot synthesis and AFM imaging of a triangular aramide macrocycle

Storz, Christof ; Badoux, Michael ; Hauke, Christopher M. ; Šolomek, Tomáš ; Kühnle, Angelika ; Bally, Thomas ; Kilbinger, Andreas F. M.

In: Journal of the American Chemical Society, 2014, vol. 136, no. 37, p. 12832–12835

Macrocyclizations in exceptionally good yields were observed during the self-condensation of N-benzylated phenyl p-aminobenzoates in the presence of LiHMDS to yield three-membered cyclic aramides that adopt a triangular shape. An ortho-alkyloxy side chain on the N-benzyl protecting group is necessary for the macrocyclization to occur. Linear polymers are formed exclusively in the absence of this...

Université de Fribourg

Photolysis of ortho-nitrobenzylic derivatives: the importance of the leaving group

Šolomek, Tomáš ; Mercier, Sébastien ; Bally, Thomas ; Bochet, Christian G.

In: Photochemical & Photobiological Sciences, 2012, vol. 11, no. 3, p. 548-555

Quantum yields for the photoinduced release of seven different commonly used leaving groups (LGs) from the o-nitroveratryl protecting group were measured. It was found that these quantum yields depend strongly on the nature of the LGs. We show that the quantum efficiency with which the LGs are released correlates with the stabilization that these LGs provide to o-nitrobenzyl-type radicals because...

Université de Fribourg

The Primary steps in excited-state hydrogen transfer: the phototautomerization of o-nitrobenzyl derivatives

Šolomek, Tomáš ; Bochet, Christian G. ; Bally, Thomas

In: Chemistry – A European Journal, 2014, vol. 20, no. 26, p. 8062–8067

The quantum yield for the release of leaving groups from o-nitrobenzyl “caged” compounds varies greatly with the nature of these leaving groups, for reasons that have never been well understood. We found that the barriers for the primary hydrogen-atom transfer step and the efficient nonradiative processes on the excited singlet and triplet surfaces determine the quantum yields. The...

Université de Fribourg

Regioselective oxidative ring opening of cyclopropyl silyl ethers: a quantum chemical study

Rinderhagen, Heiko ; Mattay, Jochen ; Nussbaum, Rafael ; Bally, Thomas

In: Chemistry, a European Journal, 2010, vol. 16, no. 24, p. 7121–7124

In contrast to the structurally and configurationally stable alkyl- or aryl-substituted cyclopropyl radical cations, cyclopropyl silyl ethers undergo spontaneous ring opening upon oxidation whereby the endocyclic C-C(O-TMS) bond is cleaved with remarkable selectivity. DFT calculations on 1-trimethylsilyloxybicyclo[4.1.0]heptane show that this selectivity arises from the topology of the potential...

Université de Fribourg

Photochemical study on the reactivity of tetrasulfur tetranitride, S₄N₄

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

In: Inorganic Chemistry, 2009, vol. 48, no. 9, p. 4075–4082

To elucidate the multifaceted but poorly understood chemistry of the pivotal polysulfur−nitrogen heterocycle, tetrasulfur tetranitride (S₄N₄, 1), its photochemistry was studied in Ar matrices. Thereby two primary intermediates and a secondary one (2−4) were detected, and their UV−vis and IR spectra were identified through specific interconversions of...

Université de Fribourg

Matrix isolation and computational study of the photochemistry of p-azidoaniline

Pritchina, Elena A. ; Gritsan, Nina P. ; Bally, Thomas

In: Physical Chemistry Chemical Physics, 2006, vol. 8, p. 719-727

The photochemistry of p-azidoaniline was studied in argon matrices in the absence and presence of oxygen. With the help of quantum chemical calculations we were able to characterize the triplet p-aminophenylnitrene as well as the cis- and trans-p-aminophenylnitroso oxides. It was found that the latter two isomers can be interconverted by selective...