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...
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In: Journal of the American Chemical Society, 2010, vol. 132, no. 41, p. 14649–14660
The [1.1.1]propellane radical cation 1•+, generated by radiolytic oxidation of the parent compound in argon and Freon matrices at low temperatures, undergoes a spontaneous rearrangement to form the distonic 1,1-dimethyleneallene (or 2-vinylideneallyl) radical cation 3•+ consisting of an allyl radical substituted at the 2-position by a vinyl...
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In: Organic Letters, 2013, vol. 15, no. 19, p. 4932–4935
The oxidation potential of thioethers constrained to be near aromatic rings is lowered, due to an antibonding interaction between the p-type sulfur lone pair with the neighboring phenyl π-system which on removal of an electron becomes a new kind of 3-electron S∴π bonding that reveals itself in the photoelectron spectrum and by an electronic transition involving the orbitals participating in...
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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.
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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...
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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...
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In: CHIMIA International Journal for Chemistry, 2016, vol. 70, no. 3, p. 164–171
Radicalcations often undergo very unexpected rearrangements. Three examples of such rearrangements are given, and it is shown how vibronic coupling between the ground and low-lying excited states may cause certain bonds that are quite solid in the neutral molecules to become so weak that they break spontaneously, even though the bond order does not change (or changes very little) on...
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In: The Journal of Organic Chemistry, 2016, vol. 81, no. 20, p. 9576–9584
High accuracy quantum chemical calculations show that the barriers to rotation of a CH2 group in the allyl cation, radical, and anion are 33, 14, and 21 kcal/mol, respectively. The benzyl cation, radical, and anion have barriers of 45, 11, and 24 kcal/mol, respectively. These barrier heights are related to the magnitude of the delocalization stabilization of each fully conjugated system. This...
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In: Physical Chemistry Chemical Physics, 2013, vol. 16, no. 5, p. 2011–2019
The electronic and vibrational absorption spectra of the radical anion and cation of p-benzoquinone (PBQ) in an Ar matrix between 500 and 40 000 cm⁻¹ are presented and discussed in detail. Of particular interest is the radical cation, which shows very unusual spectroscopic features that can be understood in terms of vibronic coupling between the ground and a very low-lying excited...
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