Electronic and structural properties of the cyclobutenodehydroannulenes
- Univ. of California, Los Angeles (USA)
Two series of cyclobutene-annelated dehydro(n)annulenes (n = 18, 24, 30) were obtained by oxidative coupling of 1,2-diethynyl-1-cyclobutenes. The properties of these macrocycles are analyzed in an experimental and computational study and compared to those of the parent 1,3,7,9,13,15-hexadehydro(18)annulene and 1,3,7,9,13,15,19,21-octadehydro(24)annulene. The analysis of the electronic absorption and {sup 1}H NMR spectra shows that the trimers possess planar diatropic (18)annulene perimeters, while the tetramers possess planar paratropic (24)annulene perimeters. The chromophores in the pentamers are conformationally more flexible, and the diatropic character of these (30)annulenes is strongly reduced. Cyclobutene annelation stabilizes all macrocycles. In particular, the fusion of cyclobutene rings stabilizes dramatically the planar (24)annulene perimeter in the tetramers and is responsible for their preferred formation in the oxidative coupling reactions. AM1 and MM2 computational studies reproduce well the experimentally observed conformational preferences of the parent dehydroannulenes.
- OSTI ID:
- 6707210
- Journal Information:
- Journal of the American Chemical Society; (USA), Journal Name: Journal of the American Chemical Society; (USA) Vol. 112:4; ISSN 0002-7863; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201 -- Chemical & Physicochemical Properties
400500* -- Photochemistry
ALKENES
ANALOG SYSTEMS
CALCULATION METHODS
CARBOXYLIC ACIDS
CYCLOALKENES
DATA ANALYSIS
ELECTRONIC STRUCTURE
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
MEASURING INSTRUMENTS
MEASURING METHODS
NMR SPECTRA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PORPHYRINS
SPECTRA