ISSN:
0009-2940
Keywords:
α-Diketones, unsaturated
;
Conformers, stable
;
UV-Vis transition energies
;
PE Spectroscopy
;
13C-NMR chemical shifts, correlation with dihedral angles CO/CO
;
Calculations, STO-3G, MMP1
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Chromophoric Systems, 1. - Conformation and Absorption of Light in Hexa-1,5-diene-3,4-dione (Divinylglyoxal)Divinylglyoxal (1) is investigated by several spectroscopic and theoretical methods in order to set up a correlation between the CO/CO dihedral angle and the transition energies in unsaturated α-diketones. According to the experimental (UV, IR, 13C-NMR, PE spectroscopy and dipole moment) and theoretical (ab initio and molecular mechanics) results, 1 exists predominantly as a C2h conformer (Θco/co=180°, ΘVinyl/co=0°). The dependence of transition energies on CO/CO dihedral angles is similar in shape to that for saturated α-diketones, but is significantly shifted to lower transition energies. 13C chemical shifts respond sensitively to CO/CO dihedral angles, and the ab initio calculated curve is supported by a few experimental results.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19911240423
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