ISSN:
0009-2940
Keywords:
4-(p-Bromoselenobenzoyl)morpholine
;
4-[(p-(Dimethylamino)selenobenzoyl]morpholine
;
Hindered rotation
;
Hammett treatment
;
Selenoamides
;
Amides
;
Selenium compounds
;
Structure elucidation
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The solid-state structures of (p-bromoselenobenzoyl)morpholine (2a) and [p-(dimethylamino)selenobenzoyl]morpholine (2b) were determined by X-ray diffraction. Both molecules show a flat selenoamide group. The larger contribution of resonance stabilization by the aromatic ring carrying the p-dimethylamino substituent is reflected by the smaller interplanar angle Θ between the aromatic ring and the selenoamide group [53.3(1)° vs. 81.1(1)°] and by the shorter length of the C=Se bond [1.824(5) Å vs. 1.840(3) Å]. The Gibbs free energy of activation of C-N bond rotation (ΔG≠rot) of five p-substituted (selenobenzoyl)morpholines was determined by dynamic 13C NMR. The activation barriers were found to range from 61.6 kJ/mol (X = NNMe2) to 75.1 kJ/mol (X = H). The ΔG≠rot values of the corresponding (thiobenzoyl)morpholines were found to be from 3.2 kJ/mol (X = NMe2) to 5.0 kJ/mol (X = H) lower. In both cases, ΔG≠rot showed an excellent linear Hammett correlation with s̰+p.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19971300108
