Switching Aromatic Character by Complexation: π to π* Change Seen in Molecular Rotation Spectra

2021 ◽  
pp. 5150-5155
Author(s):  
Hao Wang ◽  
Junhua Chen ◽  
Chunguo Duan ◽  
Xuefang Xu ◽  
Yang Zheng ◽  
...  
Keyword(s):  
Molecular Rotation ◽  
Aromatic Character

Reactions of an Aluminium(I) Reagent with 1,2-, 1,3- and 1,5-Dienes: Dearomatisation, Reversibility, and a Pericyclic Mechanism

2019 ◽  
Author(s):  
Clare Bakewell ◽  
Martí Garçon ◽  
Richard Y Kong ◽  
Louisa O'Hare ◽  
Andrew J. P. White ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Dft Calculations ◽  
Transition State ◽  
Reaction Pathways ◽  
Aromatic Rings ◽  
Aromatic Character ◽  
Pericyclic Reaction

The reactions of an aluminium(I) reagent with a series of 1,2-, 1,3- and 1,5-dienes are reported. In the case of 1,3-dienes the reaction occurs by a pericyclic reaction mechanism, specifically a cheletropic cycloaddition, to form aluminocyclopentene containing products. This mechanism has been interrogated by stereochemical experiments and DFT calculations. The stereochemical experiments show that the (4+1) cycloaddition follows a suprafacial topology, while calculations support a concerted albeit asynchronous pathway in which the transition state demonstrates aromatic character. Remarkably, the substrate scope of the (4+1) cycloaddition includes dienes that are either in part, or entirely, contained within aromatic rings. In these cases, reactions occur with dearomatisation of the substrate and can be reversible. In the case of 1,2- or 1,5-dienes complementary reactivity is observed; the orthogonal nature of the C=C π-bonds (1,2-diene) and the homoconjugated system (1,5-diene) both disfavour a (4+1) cycloaddition. Rather, reaction pathways are determined by an initial (2+1) cycloaddition to form an aluminocyclopropane intermediate which can in turn undergo insertion of a further C=C π-bond leading to complex organometallic products that incorporate fused hydrocarbon rings.

scholarly journals Real-time observation of ultrafast molecular rotation in weakly bound dimers

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Jiaqi Zhou ◽  
Chaoxiong He ◽  
Ming-Ming Liu ◽  
Enliang Wang ◽  
Shaokui Jia ◽  
...  
Keyword(s):  
Real Time ◽  
Molecular Rotation ◽  
Weakly Bound ◽  
Time Observation ◽  
Real Time Observation

scholarly journals Amethyrin-type expanded porphyrins that display anti-aromatic character upon protonation

2020 ◽  
Vol 56 (69) ◽  
pp. 9994-9997 ◽  
Author(s):  
Harrison D. Root ◽  
Daniel N. Mangel ◽  
James T. Brewster ◽  
Hadiqa Zafar ◽  
Adam Samia ◽  
...  
Keyword(s):  
Aromatic Character ◽  
Expanded Porphyrins

The use of protonation to switch nonaromatic expanded porphyrins to their corresponding anti-aromatic forms is shown.

Aromatic Character of [n]Helicenes and [n]Phenacenes

1999 ◽  
Vol 103 (33) ◽  
pp. 6669-6672 ◽  
Author(s):  
Jerome M. Schulman ◽  
Raymond L. Disch
Keyword(s):  
Aromatic Character

Aromatic character of annelated dimethyldihydropyrenes

2004 ◽  
Vol 17 (5) ◽  
pp. 393-398 ◽  
Author(s):  
Jun-ichi Aihara ◽  
Toshimasa Ishida
Keyword(s):  
Aromatic Character
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