ISSN:
0749-1581
Keywords:
13C NMR
;
15N NMR
;
Solvent effects
;
Amidine rotation barriers
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Solvent-induced 13C NMR chemical shifts of N1,N1-dimethyl-N2-phenylformamidine can be correlated with the acceptor number of solvents, AN, and also with the π* and α parameters of Kamlet and Taft. No correlation was found for the height of the rotational barrier around the C—N1 bond. The self-association of formamidine and the influence of polar, aprotic solvents cause an increase in ΔG1 of approximately 1 kJ mol-1 whereas, contrary to expectations, the ΔG1 values found in hydrogen-bonding solvents are smaller than in cyclohexane. The barrier, however, increases with the strength of the hydrogen bond and on protonation. Downfield shifts of the N1 and upfield shifts of the N2 signals were observed in the 15N NMR spectra of formamidine when the strength of the hydrogen bond with the solvent increased.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1260271105
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