2,6‐Dicyano‐1,5‐dimethyl‐4,8‐diphenylsemibullvalene. — Synthesis, Structure and the Reactions with Triplet Oxygen

Quast, Helmut; Herkert, Thomas; Witzel, Alexander; Peters, E.‐M.; Peters, Karl; Schnering, Hans Georg̀ von

doi:10.1002/cber.19941270521

Cited by 35 publications

(27 citation statements)

References 56 publications

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“…In contrast, the ambient temperature 1 H and 13 C NMR spectra of 17 are time averaged and the 13 C signals show no line broadening down to the limit of accessible low temperatures. [18,26] In a comprehensive examination of 12, we found that at all correlated levels of theory, except for the B3PW91/6-31G* method, only the C 2v homoaromatic 12 c could be located. [1,9,12,18] Using B3PW91/6-31G* we found essentially degenerate minima for both 12 c and the C s localized 12 a,b.…”

Section: Resultsmentioning

confidence: 98%

The Experimental Realization of a Neutral Homoaromatic Carbocycle

Griffiths¹,

Pivonka²,

Williams³

2011

Chemistry A European J

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Section: Resultsmentioning

confidence: 98%

The Experimental Realization of a Neutral Homoaromatic Carbocycle

Griffiths¹,

Pivonka²,

Williams³

2011

Chemistry A European J

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“…The second and third equalities in eqn (128) are consequences of the approximation (eqn (126b)) and the conservation of C s symmetry, which implies the relations in eqn (125). From eqn (127) and (128) we obtain the reduced mass associated with…”

Section: Stepmentioning

confidence: 97%

Quantum theory of concerted electronic and nuclear fluxes associated with adiabatic intramolecular processes

Bredtmann

Diestler

et al. 2015

Phys. Chem. Chem. Phys.

123

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An elementary molecular process can be characterized by the flow of particles (i.e., electrons and nuclei) that compose the system. The flow, in turn, is quantitatively described by the flux (i.e., the time-sequence of maps of the rate of flow of particles though specified surfaces of observation) or, in more detail, by the flux density. The quantum theory of concerted electronic and nuclear fluxes (CENFs) associated with electronically adiabatic intramolecular processes is presented. In particular, it is emphasized how the electronic continuity equation can be employed to circumvent the failure of the Born-Oppenheimer approximation, which always predicts a vanishing electronic flux density (EFD). It is also shown that all CENFs accompanying coherent tunnelling between equivalent "reactant" and "product" configurations of isolated molecules are synchronous. The theory is applied to three systems of increasing complexity. The first application is to vibrating, aligned H2(+)((2)Σg(+)), or vibrating and dissociating H2(+)((2)Σg(+), J = 0, M = 0). The EFD maps manifest a rich and surprising structure in this simplest of systems; for example, they show that the EFD is not necessarily synchronous with the nuclear flux density and can alternate in direction several times over the length of the molecule. The second application is to coherent tunnelling isomerization in the model inorganic system B4, in which all CENFs are synchronous. The contributions of core and valence electrons to the EFD are separately computed and it is found that core electrons flow with the nuclei, whereas the valence electrons flow obliquely to the core electrons in distinctive patterns. The third application is to the Cope rearrangement of semibullvalene, which also involves coherent tunnelling. An especially interesting discovery is that the so-called "pericyclic" electrons do not behave in the manner typically portrayed by the traditional Lewis structures with appended arrows. Indeed, it is found that only about 3 pericyclic electrons flow, in contrast to the 6 predicted by the Lewis picture. It is remarkable that the time scales of these three processes vary by 18 orders of magnitude: femtoseconds (H2(+)((2)Σg(+))); picoseconds (B4); kilosceconds (semibullvalene). It is emphasized that results presented herein are appearing in the literature for the first time.

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“…Cope rearrangements of SBV and several derivatives have already served as touchstones for various properties that are related to pericyclic reactivity, from synthesis 12,16,21,22,29 via spectroscopy 13,15,20,24,27 and kinetics 13,14,19 to electronic structure 17,18,[21][22][23][24][25][26][28][29][30][31]35 and the related thermochromicity, 3,21,22,24,29 ab initio molecular dynamics 32 , the role of tunnelling 33 , and the above-mentioned quantum dynamics simulations of IR pump-dump laser control. [2][3][4] In particular, quantum chemistry first principal calculations show that the Cope rearrangement of SBV in the electronic ground state .)…”

Section: Introductionmentioning

confidence: 99%

Optimal control of the initiation of a pericyclic reaction in the electronic ground state#

Bredtmann

Manz

2012

J Chem Sci

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Pericyclic reactions in the electronic ground state may be initiated by down-chirped pump-dump sub-pulses of an optimal laser pulse, in the ultraviolet (UV) frequency and sub-10 femtosecond (fs) time domain. This is demonstrated by means of a quantum dynamics model simulation of the Cope rearrangement of Semibullvalene. The laser pulse is designed by means of optimal control theory, with detailed analysis of the mechanism. The theoretical results support the recent experimental initiation of a pericyclic reaction. The present approach provides an important step towards monitoring asynchronous electronic fluxes during synchronous nuclear pericyclic reaction dynamics, with femto-to-attosecond time resolution, as motivated by the recent prediction of our group.

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2,6‐Dicyano‐1,5‐dimethyl‐4,8‐diphenylsemibullvalene. — Synthesis, Structure and the Reactions with Triplet Oxygen

Cited by 35 publications

References 56 publications

The Experimental Realization of a Neutral Homoaromatic Carbocycle

The Experimental Realization of a Neutral Homoaromatic Carbocycle

Quantum theory of concerted electronic and nuclear fluxes associated with adiabatic intramolecular processes

Optimal control of the initiation of a pericyclic reaction in the electronic ground state#

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