Results 151 to 160 of about 1,579 (190)
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Aromatic and Antiaromatic Dehydroannulenes
Journal of the American Chemical SocietyCyclocarbons make up an emerging family of carbon allotropes, but their instability precludes the study of their physicochemical properties. We report a synthetic route to cyclopentenone-annulated [18]- and [24]dehydroannulenes that are stable aromatic and antiaromatic models of cyclocarbon precursors. Combining NMR spectroscopy, X-ray crystallography,
Yann Lie +2 more
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Synthesis of antiaromatic tetrabenzodithiaamethyrin
Journal of Porphyrins and Phthalocyanines, 2021Bicyclo[2.2.2]octadiene(BCOD)-fused dithiaamethyrin 4 was synthesized via a “3+3” condensation method. Thermal conversion of the BCOD moieties afforded tetrabenzodithiaamethyrin 5. The highly planar structures of 4 and 5 were confirmed by X-ray diffraction studies. The 1H NMR, absorption and MCD spectra, together with TD-DFT calculations revealed that
Tetsuo Okujima +6 more
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Isophlorinoids: The Antiaromatic Congeners of Porphyrinoids
Chemical Reviews, 2016Ever since the discovery of the porphyrin ring in "pigments of life", such as chlorophyll and hemoglobin, it has become a prime synthetic target for optoelectronic properties and in the design of metal complexes. During one such early expedition on the synthesis of porphyrin, Woodward proposed that condensing pyrrole with an aldehyde under acidic ...
B. Kiran Reddy +3 more
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Experimental Determination of the Antiaromaticity of Cyclobutadiene
Science, 1999Photoacoustic calorimetry was used to quantify the antiaromaticity of 1,3-cyclobutadiene (CBD) by measuring the heat release accompanying its formation via photofragmentation of a polycyclic precursor. In combination with quantum yield measurements and thermochemical calculations, this measurement provides an enthalpy of formation for CBD of 114 ± 11 ...
, Deniz, , Peters, , Snyder
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The antiaromaticity of cyclobutadiene
Tetrahedron, 1976Abstract The antiaromaticity of cyclobutadiene systems is explored by means of theoretical studies on quinone electrochemical oxidation reactions.
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The aromaticity and antiaromaticity of dehydroannulenes
Physical Chemistry Chemical Physics, 2001The molecular structures and the magnetic properties of hexadehydro[12]annulenes and dodecadehydro[18]annulenes have been studied at ab initio and density-functional levels. The calculations show that the unsubstituted dehydro[12]annulene sustains a paratropic ring current in an external magnetic field, while the ring current for the unsubstituted ...
Jonas Juse´lius, Dage Sundholm
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Angewandte Chemie International Edition in English, 1968
AbstractAccording to quantum mechanical calculations, systems with 4n π electrons ought to have anti‐aromatic character, i.e. be destabilized by resonance. This prediction is examined for the case of cyclopropenyl anion, the simplest system having 4n π electrons (n = 1).
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AbstractAccording to quantum mechanical calculations, systems with 4n π electrons ought to have anti‐aromatic character, i.e. be destabilized by resonance. This prediction is examined for the case of cyclopropenyl anion, the simplest system having 4n π electrons (n = 1).
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Antiaromatic Ruthenacyclopentatriene Complexes
Chemical CommunicationsOnly half-sandwich ruthenacyclopentatrienes have been reported to date and their (anti)aromaticity remains unverified. Herein, we synthesize and characterize novel ruthenacyclopentatrienes adopting an octahedral geometry, which are antiaromatic.
Jiaxin Wang +4 more
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