The Geometry and Internal Rotational Barrier of Carbamic Acid and Several Derivatives

Authors

M. Remko
Steve Scheiner, Utah State UniversityFollow

Document Type

Article

Journal/Book Title

Journal of Molecular Structure: TheoChem

Publication Date

11-1988

Publisher

Elsevier

Volume

180

First Page

175

Last Page

188

Abstract

The geometries of the following carbamate-containing molecules have been optimized at the ab initio SCF level using the MINI-1, 3-21G, and 6-31G* basis sets: carbamic acid, methylcarbamate, ethylcarbamate, N-methyl methylcarbamate, N,N-dimethyl methylcarbamate, N-vinyl methyl-carbamate and N-phenyl methylcarbamate. The latter two basis sets yield geometries in best agreement with experimental data. Calculated energy barriers for rotation about the CN bond become progressively higher as the basis set is enlarged; electron correlation leads to a modest reduction. At the MP2/6-31G*//6-31G* level, the barriers lie in the range of 80–90 kJ mol⁻¹. Alkyl substitution on either end of the carbamate group increases the ⁺C=O⁻ charge separation. N-substitution reduces the electron density on the nitrogen whereas the negative charge of this atom is increased by esterification of carbamic acid.

Comments

http://www.sciencedirect.com/science/article/pii/0166128088800885

Publisher PDF is available for download through the link above.

Published by Elsevier in Journal of Molecular Structure.

Recommended Citation

The Geometry and Internal Rotational Barrier of Carbamic Acid and Several Derivatives M. Remko and S. Scheiner J. Mol. Struct., Theochem, 1988 180, 175-188.