Naslov
Deuterium Isotope Effects on C-13 Chemical Shifts in cis-Stilbene

Autori
Meić, Zlatko ; Novak, Predrag ; Vikić-Topić, Dražen ; Smrečki, Vilko

Izvornik
Magnetic resonance in chemistry (0749-1581) 34 (1996), 1; 36-41

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
NMR ; C-13 NMR ; Deuterium isotope effects ; cis-Stilbene

Sažetak
Over 100 isotope effects on C-13 chemical shifts were determined in a series of deuteriated cis-stilbene isotopomers. The magnitude and sign of these effects depend on the position and the number of deuterium atoms in the molecule, The variations in two- and three-bond effects were rationalized by steric interactions between the phenyl ring and the olefinic group, The six-bond effects in cis-stilbene isotopomers are related to the molecular Ph-C= C dihedral angle, as in other binuclear aromatic molecules, In [para-H-2]-cis-stilbene the isotope effect over ten bonds was observed, amounting to 2.0 ppb. In mono- and dideuterio-cis-stilbenes, effects over up to three bonds from the site of the deuteriation have a positive sign and decrease monotonously in magnitude, In contrast, effects through more than three bonds generally show an alternation in sign and oscillations in magnitude, In polydeuteriated cis-stilbenes, changes in sign and magnitude are governed by the additivity rule, which reproduces the observed values of isotope effects within a few percent.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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