Infrared spectra of phenylboronic acid (normal and deuterated) and diphenyl phenylboronate

Abstract

The infrared spectra of phenylboronic acid, normal and deuterated, and diphenyl phenylboronate have been recorded in the range 4000-300 cm-' and assignments of the observed frequencies have been made. The spectrum of the acid in the OH stretching region shows evidence of intramolecular hydrogen bonding. The spectrum of diphenyl phenylboronate has been interpreted by analogy with monosubstituted benzene derivatives. The two different environments of the phenyl groups in this molecule give rise to splitting of two of the characteristic vibrations of the benzene ring near 760 and 680 cm-I.

Molecular structure, vibrational spectroscopic studies and NBO analysis of the 3,5‐dichlorophenylboronic acid molecule by the density functional method

“…The strength and broadening wavenumbers of these bands suggest that intramolecular hydrogen bonding occurs in different environments of boronic acids. [24] In accordance with the above conclusion, the two O-H stretching vibrations occur at 3443 and 3397 cm −1 in the FT-IR spectrum. The same vibration occurs in the FT-Raman spectrum at 3480 and 3440 cm −1 .…”

“…The B-O asymmetric stretching band of the phenylboronic acid occurs at 1370 cm −1 in the infrared spectrum [24] and at 1375 cm −1 for the phenylboronic acid linkage. [32] These bands are very intense and should also include the asymmetric stretching vibrations, which are located at 1349 and 1350 cm −1 for phenylboronic and pentafluorophenylboronic acids, respectively.…”

“…The assignment of these bands to O-H stretching vibrations is straightforward. In the spectra of phenylboronic acid, [24] pentafluorophenylboronic acid, [25] and 3-and 4-pyridineboronic acid, [26] n-butylboronic acid [27] absorption bands at 3280, 3467, 3410, 3320 and 3306 cm −1 were assigned, which is typical for O-H bonded hydroxyl groups. The strength and broadening wavenumbers of these bands suggest that intramolecular hydrogen bonding occurs in different environments of boronic acids.…”

“…[32] These bands are very intense and should also include the asymmetric stretching vibrations, which are located at 1349 and 1350 cm −1 for phenylboronic and pentafluorophenylboronic acids, respectively. [24,33] Kahraman et al [32] assigned the band around 1370 cm −1 to the υ(B-O) stretching vibrations for the homo-and hetrotrinuclear boron complexes. The corresponding bands were observed at 1392 cm −1 as very strong bands in FT-IR and at 1409 cm −1 as weak bands in FT-Raman spectra of the 3,5-dcpba molecule.…”

Preparation, structural and thermal studies of boroxine adducts having aryl boronic acids and pyrazoles

“…The crystallographic data, hydrogen bond distances, selected bond lengths and angles are shown in Tables 1, 2, Appendix S1 and S2, respectively. (Faniran and Shurvell, 1968). The formation of adducts have also been confirmed by the 1 H-NMR spectra, showing the prominent downfield shift in each case with respect to free compounds as shown in Table S3.…”