Résonance magnétique nucléaire 13C des dérivés allyliques de la colonne IV-A, de type (C6H5)3ECH2CH=CH—CH3. Effets électroniques du substituant du noyau aromatique

1984 ◽  
Vol 62 (1) ◽  
pp. 133-135 ◽  
Author(s):  
E. Matarasso-Tchiroukhine
Keyword(s):  
Excitation Energy ◽  
Electronic Excitation ◽  
Inductive Effect ◽  
Chemical Shifts ◽  
Aromatic Nucleus ◽  
Electronic Excitation Energy ◽  
Nmr Study ◽  
Résonance Magnétique ◽  
The Mean ◽  
C Nmr

The 13C nmr study of the series (C6H5)3ECH2CH=CH—CH31E shows, for the aromatic nucleus, a polarization consistent with a mesomeric electron withdrawing effect of the substituent in the case of E = Si, Ge, Sn; inversely, a mesomeric donating effect, in the case E = Pb, involving a higher electronegativity for Pb; and a donating π inductive effect, in the case E = C. The mean electronic excitation energy seems to dominate the chemical shifts of the aromatic carbons Cipso and Cortho, as well as the coupling 0J(13C—207Pb).

Dérivés allyliques de la colonne IV-A, de type R3ECH2CH=CH—CH3 et R3ECH(CH3)CH=CH2. Approche des effets électroniques par résonance magnétique nucléaire 13C et 1H

1983 ◽  
Vol 61 (11) ◽  
pp. 2476-2485 ◽  
Author(s):  
E. Matarasso-Tchiroukhine ◽  
P. Cadiot
Keyword(s):  
Chemical Shifts ◽  
Main Group ◽  
Group Element ◽  
Appreciable Change ◽  
Spectroscopic Parameters ◽  
Group Electronegativity ◽  
Nmr Study ◽  
Résonance Magnétique ◽  
Derivatives Of ◽  
C Nmr

A comparative 1H and 13C nmr study of allylic derivatives of the IV-A group elements, of the type R3ECH2CH=CH—CH31E, Z and R3ECH(CH3)CH=CH2, 2, was performed (R = —C6H5, —CH3, E = C, Si, Ge, Sn, Pb). The present paper dealing with the allylic moiety concerns both the chemical shifts, δ1H and δ13C, and the homonuclear J(H—H) and heteronuclear couplings 1J(13C—H), nJ(13C—E), n = 1 to 4, nJ(E—C—H), n = 2 and 5. The spectra are consistent with a σ-allylic structure. In order to obtain an inductive order for the groups G(E) = —E(C6H5)3 a coherent group electronegativity scale was established. The intrinsic group electronegativities, without appreciable change, obey the following sequence:[Formula: see text]Both the changes along the series, in spectroscopic parameters, δ1H, δ13C, and the unusually large heteronuclear couplings, 2J(E—C—H), 5J(E—C—H), 4J(E—13C) (E = Sn, Pb), are interpreted in terms of an electronic mesomeric donating effect for the substituent σ, R3ECH2— and R3ECH(CH3)—, by σ–π hyperconjugation. Factors intrinsic to the main-group element control the chemical shifts δ1Hα and δ13Cα. The s-character of the bond Cα—Hα appears to control the 1J(13Cα—Hα) couplings; no correlation with a σ → π hyperconjugation could be established.

Theoretical investigation of electronic excitation energy transfer in bichromophoric assemblies

2008 ◽  
Vol 128 (7) ◽  
pp. 074505 ◽  
Author(s):  
Burkhard Fückel ◽  
Andreas Köhn ◽  
Michael E. Harding ◽  
Gregor Diezemann ◽  
Gerald Hinze ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Theoretical Investigation ◽  
Electronic Excitation ◽  
Excitation Energy Transfer ◽  
Electronic Excitation Energy Transfer ◽  
Electronic Excitation Energy
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