Ab initio and molecular mechanics (MM3) calculations on alkyl- and arylboronic acids

2008

The experimental and theoretical vibrational spectra of 4-chloro-and 4-bromophenylboronic acids (abbreviated as 4Clpba and 4Brpba) were studied. The Fourier transform Raman and Fourier transform infrared (FTIR) spectra of 4Clpba and 4Brpba molecules were recorded in the solid phase. The structural and spectroscopic analyses of the molecules were made by using Hartree-Fock and density functional harmonic calculations. In both 4Clpba and 4Brpba only one form was most stable using B3LYP level with the 6-311++G(d,p) basis set. Selected experimental bands were assigned and characterized on the basis of the scaled theoretical wavenumbers by their total energy distribution (TED). Finally, geometric parameters as well as infrared (IR) and Raman bands were compared with the experimental data of the molecules.

Section: Geometrical Structuresmentioning

confidence: 77%

DFT simulations and Vibrational spectra of 4‐chloro and 4‐bromophenylboronic acid molecules

2008

“…[6] The boronic acid moiety has also been incorporated into amino acids and nucleosides as antitumor, antiviral agents. [7] Phenylboronic acid is a versatile building block in organic synthesis and an important intermediate in the synthesis of active compounds in agrochemical and pharmaceutical industries. [8] In order to study these biologically important type of molecules by density functional theory (DFT) methods, the necessary parameters had to be developed.…”

Section: Introductionmentioning

confidence: 99%

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

Saravanakumar

Sundaraganesan

et al. 2010

In this study, the Fourier-transform infrared (FT-IR) and FT-Raman spectra of 3,5-dichlorophenylboronicacid (3,5-dcpba) were recorded in the solid phase. The structural and spectroscopic analysis of the 3,5-dichlorophenylboronic was made by using density functional harmonic calculations. There are three conformers for this molecule. The computational results diagnose the most stable conformer of 3,5-dcpba as the ct form. The geometrical parameters and energies have been obtained for all three conformers from DFT (B3LYP) with 6-311++G(d,p) basis set calculations. The vibrations of stable and unstable conformers of 3,5-dcpba are researched by using quantum chemical calculations. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational modes calculated with the scaled quantum mechanics (SQM) method. The stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using the natural bond orbital (NBO) analysis. The results show that the charge in electron density (ED) in the π * and σ * antibonding orbitals and E2 energies confirms the occurrence of ıntermolecular charge transfer (ICT) within the molecule. Finally, the calculation results were applied to simulated infrared and Raman spectra of the title compound, which show agreement with the observed spectra.

“…[13] The boronic acid moiety has been incorporated into amino acids and nucleosides as anti-tumor and anti-viral agents. [14] It's noted that vibrational spectra of arylboronic acid were reported by Santucci and Gilman. [15] Faniran and Shurvell [16] have assigned the infrared spectra of phenylboronic acid and deuterated phenylboronic acid.…”

Section: Introductionmentioning

confidence: 99%

DFT, FT‐Raman, FT‐IR and NMR studies of 2‐fluorophenylboronic acid

Erdoğdu

Güllüoğlu

2009

The experimental and theoretical vibrational spectra of 2-fluorophenylboronic acid (2fpba) were studied. The Fourier transform Raman and Fourier transform infrared spectra of the 2fpba molecule were recorded in the solid phase. The structural and spectroscopic analysis of the molecule was carried out by using Hartree-Fock and density functional harmonic calculations. For the title molecule, only one form was found to be the most stable structure, by using B3LYP level with the 6-31++G(d,p) basis set. Selected experimental bands were assigned and characterized on the basis of the scaled theoretical wavenumbers by their total energy distribution (TED). The 1 H and 13 C nuclear magnetic resonance (NMR) chemical shifts of the 2fpba molecule were calculated using the Gauge-Invariant-atomic orbital (GIAO) method in DMSO solution using IEF-PCM model and compared with the experimental data. Finally, geometric parameters, vibrational wavenumbers and chemical shifts were compared with available experimental data of the molecule.