ISSN:
0009-2940
Keywords:
Conformational analysis
;
“Push-pull” interaction
;
Benzene ring, deformation to boat and twist-boat forms
;
Calculations, AM1
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The X-ray analyses of three 1,3,5-tris(alkylamino)-2,4,6-trinitrobenzenes (alkyl = iPr, neopentyl, tBu; 1d - f) show their benzene rings to be highly distorted towards boat (1d iPrNH2) and twist-boat (1e,f) forms. The patterns found for intramolecular donor-acceptor interaction and hydrogen bonding depend on the conformation of the benzene core: boat structures have the “stern” amino group strongly donating to the “bow” nitro group in the para position and two stronger hydrogen bonds between the substituents on the “side” of the boat, whereas twist-boat structures have two amino groups strongly interacting with the nitro group in their common ortho position to which there are also two strong hydrogen bonds. 1d - f undergo conformational exchange on the 13C-NMR time scale at room temperature. Cooling to 220 K allows detection of all carbon signals and shows C1 symmetry to be present. AM1 calculations reproduce the distortions of 1d - f. Computations on several 2,4,6-tridonor-substituted 1,3,5-trinitrobenzenes indicate that the pronounced deviations from planarity in 1a - f originate largely from electronic effects.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19911240809
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