Investigation of the charge state of heteroatoms in organic compounds of third-row elements by x-ray fluorescence spectroscopy 10. Correlations between values of the shifts of the k? lines of sulfur, phosphorus, and chlorine and the values of the effective charges of these atoms determined from semiempirical quantum-chemical calculations

1991 ◽  
Vol 40 (2) ◽  
pp. 345-352
Author(s):  
G. N. Dolenko ◽  
A. L. Litvin ◽  
V. P. Elin ◽  
O. Kh. Poleshchuk
Keyword(s):  
Fluorescence Spectroscopy ◽  
Charge State ◽  
Quantum Chemical Calculations ◽  
Organic Compounds ◽  
Quantum Chemical ◽  
X Ray ◽  
Effective Charges ◽  
Semiempirical Quantum Chemical Calculations

Sterically Crowded Heterocycles. VIII. Preparative Photoisomerization of Some Imidazo[1,2-a]pyridines

1996 ◽  
Vol 61 (10) ◽  
pp. 1473-1488 ◽  
Author(s):  
Richard Kubík ◽  
Stanislav Böhm ◽  
Jan Čejka ◽  
Vladimír Havlíček ◽  
Tomáš Strnad ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Mass Spectra ◽  
X Ray ◽  
Uv Illumination ◽  
Derivatives Of ◽  
Semiempirical Quantum Chemical Calculations

UV-Illumination of (Z)-3-(2-phenylimidazo[1,2-a]pyridin-3-yl)-1,3-diphenylprop-2-en-1-one (1a) or its 6-methyl and 6-iodo derivatives 1c and 1g resulted in minor (E)-isomers 2a, 2c, and 2g and prevailing (E,Z)-mixtures of N-(pyridin-2-yl)-[(3,5-diphenylfuran-2-yl)phenylmethylidene]amines 3a, 3c, and 3g while only corresponding furanoic derivatives 3b and 3d-3f were obtained from 5-methyl (1b), 7-methyl (1d), 8-methyl (1e), and 5-phenyl (1f) derivatives of the (Z)-ketone 1a. VIS-Illumination of (Z)-1,3-diphenyl-3-(2-phenylimidazo[1,2-a]benzo[I]quinolin-3-yl)prop-2-en-1-one (4) led to N-(benzo[h]quinolin-2-yl)-[(3,5-diphenylfuran-2-yl)phenylmethylidene]amine (5). Photoisomers 2a, 2c, 2g, 3a-3g, and 5 were isolated and the molecular structure of 3c was X-ray determined. Mechanism of the photoisomerization is discussed using semiempirical quantum chemical calculations and compared with mass spectra of compounds 1a, 2a, 3a, 1g, 2g, and 3g.

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