In: Physical Chemistry Chemical Physics, 2015, vol. 17, no. 16, p. 10624–10629
The well-studied benzene dimer radical cation, which is prototypical for this class of species, has been reinvestigated computationally. Thereby it turned out that both the σ-hemibonded and the half-shifted sandwich structures of the benzene dimer cation, which had been independently proposed, represent stationary points on the B2PLYP-D potential energy surfaces. However, these structures belong...
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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....
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In: ChemPhysChem, 2006, vol. 7(6), p. 1268-1275
2,6-Difluorophenylnitrene was reinvestigated both experimentally, in Ar matrices at 10 K, and computationally, by DFT and CASSCF/CASPT2 calculations. Almost-pure samples of both neutral rearrangement products (the bicyclic azirine and the cyclic ketenimine) of a phenylnitrene were prepared and characterized for the first time. These samples were then subjected to X-irradiation in the presence of...
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In: The Journal of Physical Chemistry, 2012, vol. 116, no. 41, p. 10203–10208
High-level G3X(MP2)-RAD calculations have been carried out to examine the effect of interposing a “connector” group (W) on the interaction between a substituent (X) and the radical center in carbon-centered radicals (•CH₂–W–X). The connector groups include −CH₂–, −CH═CH–, −C≡C–, −p-C₆H₄–, −m-C₆H₄–, and −o-C₆H₄–,...
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In: Nature Chemistry, 2010, vol. 2, no. 3, p. 165-166
Electromerism is an unfamiliar concept to many chemists and refers to molecules that are not conventional isomers but instead differ in how the electrons are distributed across their structure. A novel example of such electromers has now been demonstrated.
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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...
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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...
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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...
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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...
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In: Chemistry - A European Journal, 2006, vol. 12(17), p. 4559-4567
Three tricyclic vinylcyclobutanes (3-methylenetricyclo[5.3.0.02,6]decanes 1-3) have been subjected to ionization by photoinduced electron transfer in solution and by X-irradiation in Ar matrices. All three compounds undergo oxidative cycloreversion; the cleavage of the four-membered ring, however, occurs in a different direction depending on the presence of a methyl group...
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