William Moyes

The electronic structure of substituted benzenes; AB initio calculations and photoelectron spectra for the methyl- and fluoro-benzenes and fluorotoluenes

Abstract The valence shell orbital energies for the various title compounds are assigned by a combination of He(I) and He(II) photoelectron spectra and ab initio MO calculations of double and single zeta quality.

The electronic structure of substituted benzenes; ab initio calculations and photoelectron spectra for phenol, the methyl- and fluoro-derivatives, and the dihydroxybenzenes

Abstract The valence shell orbital energies for the ten title compounds are investigated by a combination of He(I), and He(II) photoelectron spectra and ab initio MO calculations of single and double zeta quality.

The electronic structure of substituted benzenes; a study of aniline, the toluidines, phenylenediamines and fluoroanilines by photoelectron spectroscopy and ab initio calculations

The ten title compounds have been investigated by a combination of He(I) and He(II) photoelectron spectroscopy and ab initio molecular orbital studies, of single and double zeta quality. Although the compounds are of low symmetry, the calculations suggest that many of the molecular orbitals have a pseudo-benzene (D6h) character; this is borne out by the systematic trends in the observed spectra. The latter are assigned in some detail, and variations between compounds are discussed, in particular in relation to the corresponding isoelectronic series of substituents in PhX where X = CH3, NH2, OH and F.

The electronic structure of substituted benzenes; ab initio calculations and photoelectron spectra for nitrobenzene, the nitrotoluenes, dinitrobenzenes and fluoronitrobenzenes

Abstract The photoelectron spectra of the title compounds have been investigated by He(I) and He(II) photoelectron spectroscopy and by ab initio MO calculations. The spectra have been assigned in some detail and compared with those of other mono-substituted benzenes.

The electronic structure of substituted benzenes: ab initio calculations and photoelectron spectra for benzonitrile, the tolunitriles, fluorobenzonitriles, dicyanobenzenes and ethynylbenzene

Abstract The photoelectron spectra of the title compounds have been investigated by He(I) and He(II) photoelectron spectroscopy and by ab initio MO calculations. The spectra are assigned in some detail, on the basis of their relationship to the corresponding IPs in benzene, and are compared with those of other substituted benzenes.

The electronic structure of conjugated molecules. Non-empirical calculations for the benzenium, pyridinium, pyrylium, and thiopyrylium cations and a comparison of the last with phosphorin

Non-empirical calculations on the title compounds and of the allyl carbonium ion are reported. For the second row compounds(1a and g), the role of the 3d-orbitals is that of polarisation functions rather than strongly bonding orbitals. The orbital energies of all the cyclic cations can be correlated directly with benzene and phosphorin, such minor rearrangements of orbital ordering that occur can be readily interpreted in terms of the heteroatom orbital energies. Support for the highest occupied orbital sequence of binding energies in phosphorin, 3b1 < 1a2 < 13a1 < 8b2, as suggested by Schweig is given. The population analyses for the compounds are discussed. The hydrogen atoms absorb much of the positive charge in the cations (1a—e). The internal electric fields arising from the populations are evaluated, and compared with the observed chemical shifts; the anomalous shifts in the thiopyrylium cation (1a) are attributed to ring current effects, which are substantial in (1a) but probably much smaller or absent in the other cations, as evidenced by the dissociations of the π-electrons into well separated pairs. Some reactions of the second row compounds arise directly from the molecular orbital ordering and are discussed.