Ab initio studies of push–pull systems

Twelve push–pull ethylene derivatives, NH2CH=CHX, NH2C≡CCH=CHX, and −OCHX=CHX (with X=BH2, C≡N, NO2, and CH2+) have been studied by ab initio calculations. The rotational barrier around the central double bond was chosen as a probe for push–pull effects, as push–pull effects would remove electron de...

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Bibliographic Details
Published in:Structural chemistry 2007-06, Vol.18 (3), p.399-407
Main Authors: Rattananakin, Pornpun, Pittman, Charles U., Collier, Willard E., Saebø, Svein
Format: Article
Language:English
Subjects:
Electron density
Elongated structure
Hybrid structures
Mathematical analysis
Nitrogen dioxide
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Summary:Twelve push–pull ethylene derivatives, NH2CH=CHX, NH2C≡CCH=CHX, and −OCHX=CHX (with X=BH2, C≡N, NO2, and CH2+) have been studied by ab initio calculations. The rotational barrier around the central double bond was chosen as a probe for push–pull effects, as push–pull effects would remove electron density from the central double bond. The amount of reduction of double bond character will increase with the contribution of the zwitterionic resonance hybrid structure. Complete geometry optimizations and calculations of vibrational frequencies were performed for all minima and transition state structures of these 12 systems. The calculations were carried out with the B3LYP and MP2 methods using the 6-311+G(d,p) and the 6-311++G(d,p) basis sets. All the systems investigated exhibited properties consistent with push–pull effects such as elongated C=C double bonds, dipolar electronic structures, and reduced barriers to internal rotation.
ISSN:1040-0400
1572-9001
DOI:10.1007/s11224-006-9140-z