Structural study of 1- and 2-naphthol: new insights into the non-covalent H–H interaction in cis-1-naphthol. Issue 6 (26th January 2022)

• Record Type: Journal Article
• Authors: Hazrah, Arsh S.; Nanayakkara, Sadisha; Seifert, Nathan A.; Kraka, Elfi; Jäger, Wolfgang
• Is Part Of: Physical chemistry chemical physics. Volume 24:Issue 6(2022)
• Page Start: 3722
• Page End: 3732
• Publication Date: 2022-01-26
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d1cp05632h
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : The close-contact H–H atom interaction in cis -1-naphthol was characterized with microwave spectroscopy and several theoretical approaches using the other naphthol isomers as internal references. Abstract : Previous microwave studies of naphthol monomers were supplemented by measuring spectra of all 13 C mono-substituted isotopologues of the cis - and trans -conformers of 1-naphthol and 2-naphthol in their natural abundances. The resulting data were utilized to determine substitution structures and so-called semi-experimental effective structures. Results from electronic structure calculations show that the OH group of cis -1-naphthol points ≈6° out of plane, which is consistent with the inertial defect data of cis - and trans -1-naphthol. The non-planarity of cis -1-naphthol is a result of a close-contact H-atom–H-atom interaction. This type of H–H interaction has been the subject of much controversy in the past and we provide here an in-depth theoretical analysis of it. The naphthol system is particularly well-suited for such analysis as it provides internal standards with its four different isomers. The methods used include quantum theory of atoms in molecules, non-covalent interactions, independent gradient model, local vibrational mode, charge model 5, and natural bond orbital analyses. We demonstrate that the close-contact H–H interaction is neither a purely attractive nor repulsive interaction, but rather a mixture of the two.