An integrated approach to the study of intramolecular hydrogen bonds in malonaldehyde enol derivatives and naphthazarin: trend in energetic versus geometrical consequences

作者：Musin Ryza N; Mariam Yitbarek H^*

来源：Journal of Physical Organic Chemistry, 2006, 19(7): 425-444.

DOI：10.1002/poc.1102

• intramolecular hydrogen bonding
• malonaldehyde enol
• naphthazarin
• dihydroxynaphthoquinone
• resonance-assisted hydrogen bonds
• intractable interactions
• energetic
• geometrical
• and electronic consequences
• atoms in molecules (AIM)
• natural bond orbital (NBO)

Density functional and atoms-in-molecules (AIM) and natural bond orbital (NBO) approaches have been applied in the study of energetic (E), geometrical (G) and electronic (AIM and NBO) consequences of H bonding in malonaldehyde (MAE) derivatives and naphthazarin (NZ). AIM parameters and other measures of HB strength were used: (a) for the verification of (i) the reliability of the O center dot center dot center dot O distance (G consequence) as an indicator of IMHB strength; (ii) the capacity of the classically computed energetic parameters (Delta E(SE)s) to serve as acceptable measures of IMHB strength; and (b) for the separation of the Delta E(SE)s into (i) stabilization (HB) energies (E(HSE)s) that serve as apparent IMHB energies (E(HB,A)s), and (ii) stabilization (isomerization) energies (ENSES) that do not (owing to intractable contributions that are not germane to the solitary HB donor(D)-acceptor(A) interactions). Some of the sources of the anomalies have been rationalized. AIM topological properties were used to study the nature of the IMHB interactions. An exponential parametric model for the correlation of E-HSE with the O center dot center dot center dot O distance, which has asymptotic characteristics at long O center dot center dot center dot O distances, was obtained. The model (a) has predictive ability, that is, can be used to estimate, in an empirical manner, E(HB,A)s that are otherwise grossly underestimated, and (b) can treat both the MAE derivatives and the NZ systems even though they possess very different resonant spacers connecting the HB D-A segments. MAE and NZ are also demonstrated to have essentially the same IMHB strength. By contrast, a quadratic model for E-HSE-HB distance correlation was found to be unphysical. Use of electronic consequences of H bonding was shown to be essential for study of IMHBs with intractable interactions. Thus, AIM energy density and NBO second-order interaction energy parameters were used for the verification of predictions of IMHB strengths made on the bases of energetic and geometrical consequences.

• 出版日期2006-7