TY  - JOUR
A1  - Baranac-Stojanovic, Marija
A1  - Klaumuenzer, Ute
A1  - Markovic, Rade
A1  - Kleinpeter, Erich
T1  - Structure, configuration, conformation and quantification of the push pull-effect of 2-alkylidene-4- thiazolidinones and 2-alkylidene-4,5-fused bicyclic thiazolidine derivatives
N2  - Structures of a series of push-pull 2-alkylidene-4-thiazolidinones and 2-alkylidene-4,5-fused bicyclic thiazolidine derivatives were optimized at the B3LYP/6-31G(d) level of theory in the gas phase and discussed with respect to configurational and conformational stability. Employing the GIAO method, C-13 NMR chemical shifts of the C-2, C-2', C-4 and C-5 atoms were calculated at the same level of theory in the gas phase and with inclusion of solvent, and compared with experimental data. Push-pull effect of all compounds was quantified by means of the quotient pi*/pi, length of the partial double bond, C-13 NMR chemical shift difference (Delta delta(C=C)) and H-1 NMR chemical shifts of olefinic protons. The effect of bromine on donating and accepting ability of other substituents of the push- pull C=C double bond is discussed, too.
Y1  - 2010
UR  - http://www.sciencedirect.com/science/journal/00404020
U6  - https://doi.org/10.1016/j.tet.2010.09.040
SN  - 0040-4020
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Klaumuenzer, Ute
T1  - Quantification of the push-pull Effect in disubstituted alkynes - Application of occupation quotients pi*/pi and C-13 chemical shift differences Delta delta(C C)
JF  - Journal of molecular structure
N2  - Structures, C-13 chemical shifts, and the occupation quotients of anti-bonding pi* and bonding pi orbitals of the C  C triple bond along a series of push-pull alkynes (p)X-C6H4 C(O)-C  C-NH-C6H4-Y(P) (X,Y= H, Me, OMe, NMe2, NO2, COMe, COOMe, F, Cl, Br) were computed at the DFT level (B3LYP/6-311G**) of theory. Both the stereochemistry (cis/trans-isomers) by steric twist and the push-pull character by both C-13 chemical shift differences (Delta delta(C  C)) and the occupation quotient (pi(C  C)/pi(C  C)) were studied; the latter two parameters can be readily employed to precisely quantify the push-pull effect in alkynes. (C) 2014 Elsevier B.V. All rights reserved.
KW  - Push-pull effect
KW  - C-13 chemical shift difference Delta delta(C  C)
KW  - Occupation quotient pi*/pi
KW  - Push-pull alkynes
KW  - Steric hindrance
Y1  - 2014
U6  - https://doi.org/10.1016/j.molstruc.2014.05.072
SN  - 0022-2860
SN  - 1872-8014
VL  - 1074
SP  - 193
EP  - 195
PB  - Elsevier
CY  - Amsterdam
ER  -