Deuterium isotope effects on (13)C NMR chemical shifts reflect the smaller steric size of CD(3) compared to CH(3) groups
A CD(3) group close in space to (but many bonds distant from) a carbon atom A causes a substituent effect on the chemical shift of C(A) that is algebraically smaller than the effect of a CH(3) group, in agreement with the notion of shorter C-D relative to C-H bonds. Hence, the deuterium isotope effect of CD(3) upon delta(C(A)) is shielding when the substituent effect is deshielding, and vice versa.
Ibrom
K
Institut fur Organische Chemie, Technische Universitat Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany.
Kohn (ne Wentzel) G
Boeckmann
KU
Kraft
R
Holba-Schulz
P
Ernst
L