Carbon-13 chemical shift tensors of carboxylic acids: GIAO calculations in acetic acid + methylamine dimer

GIAO calculations are presented of the¹³C chemical shift tensors of the carboxyl group in the dimer of acetic acid with methylamine. The calculations indicate that the local geometrical parameters describing the carboxyl group are related linearly to the distance between the proton and oxygen atom of the hydroxyl group, which is also a measure of the strength of the hydrogen bond. The individual principal components of the chemical shift tensor exhibit very different dependences on the O—H distance. While δ33 is almost independent of the O—H distance, δ22 varies by more than 70 ppm for O—H distances ranging from 0-8 A to 1-5 A. The calculated values indicate that the difference between the in-plane shielding components, δ11 and δ22, can be used as a measure of the relative delocalization of the n electrons of the carbonyl group, the strength of the hydrogen bond anc the local geometry of the carboxyl group. © Taylor & Francis Group, LLC.

Duke Scholars

Author Julio Cesar Facelli Biostatistics & Bioinformatics, Division of Translational Bi ...