TY  - JOUR
A1  - Wentrup, Curt
A1  - Koch, Rainer
A1  - Kleinpeter, Erich
T1  - Twisted C=C Double Bonds with Very Low Rotational Barriers in Dioxanediones and Isoxazolones Determined by Low-Temperature Dynamic NMR Spectroscopy and Computational Chemistry
JF  - European journal of organic chemistry
KW  - NMR spectroscopy
KW  - Twisted double bonds
KW  - Push-pull effect
KW  - Density functional calculations
Y1  - 2016
U6  - https://doi.org/10.1002/ejoc.201600931
SN  - 1434-193X
SN  - 1099-0690
SP  - 4985
EP  - 4990
PB  - Wiley-VCH
CY  - Weinheim
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  -