STO-3G MO calculations on structures and internal rotational barriers of phenol, benzoyl X(X = H, F, CH3, CN, OCH3), acetyl fluoride, acetyl cyanide, and carbonyl cyanide

Abstract The side chain geometry and some adjacent bond lengths and angles of the ring are optimized at the STO-3G level of molecular orbital theory for the planar and orthogonal forms of benzoyl X(X = H, F, CN, CH3, OCH3). Similar calculations are reported for acetyl fluoride, acetyl cyanide, and carbonyl cyanide, for which experimental structures and reliable internal barriers are available. The calculated barriers for the benzoyl compounds suggest steric hindrance by X in the ground state as a major cause of the variation in the barrier magnitudes. Good agreement between calculated and experimental geometries for acetyl cyanide and carbonyl cyanide, as well as for the internal rotational barrier in the former, are taken to imply a reliable calculated geometry for benzoyl cyanide. A total geometry optimization for phenol agrees fairly well as for the internal rotational barrier in the ture and also with the direction and magnitude of the dipole moment. Optimization of the ring geometry does not lower the calculated internal rotation barrier.

[1]  M. Yáñez,et al.  Protonation and proton affinity of anisole. A theoretical study , 1979 .

[2]  W. G. Fateley,et al.  Torsional frequencies in the far infrared—V. Torsions around the CC signle bond in some benzaldehydes, furfural, and related compounds☆ , 1967 .

[3]  Ramesh K. Kakar,et al.  Microwave Spectrum of Benzaldehyde , 1970 .

[4]  P. Diehl,et al.  The structure and intramolecular motion of benzaldehyde as studied on the basis of proton spectra with 13C satellites of the oriented molecule , 1980 .

[5]  P. Diehl,et al.  Anisole, acetophenone and benzoic acid methyl ester oriented in a nematic phase: Structure and internal motion , 1977 .

[6]  Leo Radom,et al.  Molecular orbital theory of the electronic structure of organic compounds. XII. Conformations, stabilities, and charge distributions in monosubstituted benzenes , 1972 .

[7]  Niels Larsen,et al.  Microwave spectra of the six mono-13C-substituted phenols and of some monodeuterated species of phenol. Complete substitution structure and absolute dipole moment , 1979 .

[8]  A. J. Bruce,et al.  Infrared spectroscopic studies of partially deuterated ethanes and the r0, rz, and re structures , 1979 .

[9]  R. Kakar.  Microwave Spectrum of Benzoyl Fluoride , 1972 .

[10]  S. Samdal,et al.  An electron-diffraction study of the molecular structure of 2-chlorobenzaldehyde , 1976 .

[11]  M. Paddon-Row,et al.  Possibility of .pi.-electron donation by the electron-withdrawing substituents CN, CHO, CF3, and +NH3 , 1980 .

[12]  M. Gordon,et al.  Molecular orbital theory of the electronic structure of organic compounds. I. Substituent effects and dipole moments. , 1967, Journal of the American Chemical Society.

[13]  J. Clymer,et al.  Deuteron quadrupole coupling in hydrogen bonded systems. IV. Deuteron quadrupole coupling in substituted phenols , 1981 .

[14]  A. C. Hopkinson,et al.  Theoretical study of substituent effects on the acidity of the methyl group: Structure of anions CH2X− , 1980 .

[15]  F. Nicolaisen,et al.  Far-infrared gas spectra of phenol, 4-fluorophenol, thiophenol and some deuterated species: barrier to internal rotation , 1974 .

[16]  L. Pierce,et al.  Microwave Spectrum, Internal Barrier, Structure, Conformation, and Dipole Moment of Acetyl Fluoride , 1959 .