Universal Journal of Chemistry Vol. 6(2), pp. 21 - 32
DOI: 10.13189/ujc.2018.060202
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Synergistic Effects of Conjugation and Polarization on Dual Amide Hydrogen-bonding in CCl4: Theory and Experiment


Shannon G. Lieb 1,*, Paula LeBlanc 2
1 Emeritus, Butler University, 4600 Sunset Avenue, Indianapolis, United States
2 Department of Anesthesia, Baylor College of Medicine, United States

ABSTRACT

The doubly hydrogen-bonded dimer of pyrrolidinone (γ-lactam) is used as a benchmark for the effect of conjugation on the strength and extent of hydrogen-bonding of the compounds Oxindole and Isoxindole. The experimental portion of this project consists of collecting the FTIR spectrum of γ-lactam, Oxindole and Isoxindole in CCl4. The concentrations and temperatures were varied to determine the thermodynamic properties of ΔHd, ΔSd and Kd. In addition, the spectroscopic parameters of the difference of the monomer and dimer N-H stretching frequencies (Δν) and the ratio of the molar extinction coefficients of the dimer and monomer (εdm) are experimentally determined. The values of ΔHd, ΔSd, Δν and εdm are computed using MP2 and B3LYP methods with 6-31G** and 6-31+G** basis sets. The experimental values are best described by B3LYP/6-31G**with the incorporation of the dielectric effect (PCM) of CCl4. The experimental and computational results support the results of increased or decreased hydrogen-bond strength due to conjugation effects on the polarization of the monomers in forming dimers.

KEYWORDS
Hydrogen-bonding, Lactams, Conjugation Effects, Electrostatic Potential, Equilibrium Constants

Cite this paper
Shannon G. Lieb , Paula LeBlanc . "Synergistic Effects of Conjugation and Polarization on Dual Amide Hydrogen-bonding in CCl4: Theory and Experiment." Universal Journal of Chemistry 6.2 (2018) 21 - 32. doi: 10.13189/ujc.2018.060202.