Sulphur ionization potential

Relative differences between S 2p3/2 and O 1 s ionization potentials show a characteristic separation for oxygen-bound and sulphur-bound sulphoxides. It is clearly shown in Table 20 that sulphur-bound complexes have (O 1 s-S 2p3/2) relative shifts of 365.0 eV, while oxygen-bound complexes have relative shifts of 365.8 eV. Infrared and X-ray crystallographic results also show that most neutral platinum and palladium dialkyl sulphoxide complexes contain metal-sulphur rather than metal-oxygen bonds, while first-row transition metals favour oxygen-bonded sulphoxide. 

Since alkylation greatly reduces the ionization potential of benzene derivatives it was hoped that alkylated benzene cations could be prepared by oxidation in sulphuric acid (Bolton and Carrington, 1961b Hulme, unpublished results). However, although oxidation of p-xylene... 

The rate of the SN2 reaction (27 + 28 — 29) correlated well with the ionization potential of the lone pairs on the sulphur atom. The ionization potential was measured by photoelectron spectroscopy and is a direct measure of the energy of the HOMO. 

Sulphur-Halogen Compounds.— The reaction of gaseous SFg with carbon in a heated Knudsen cell has been studied by mass spectrometry, and several new molecular species, including SF, SFa, and SCF2, have been identified. Ionization potentials, with an estimated accuracy of 0.10 eV, have been obtained and LHq for the process ... 

The explanation of this effect can be conceived as follows. Phenol has a fairly high dipole moment and has no low-energy acceptor orbitals, whereas iodine has no dipole moment hence interactions with iodine may be expected to have more covalent character than the analogous reactions with phenol. Accordingly, iodine will react more readily with the better polarizable reaction partners possessing lower ionization potentials. Similar considerations may be employed to interpret, for example, the sequence of basic strengths of primary, secondary and tertiary amines [Dr 63], and the sequence of acid strengths of iodine monochloride, elemental bromine, elemental iodine, phenol and sulphur dioxide [Dr 62]. 

MePhSNuc then undergoes further rapid reaction with a second mole of nucleophile. A correlation between the nucleophilic reactivity of a series of compounds containing the C=S group and the ionization potentials of the lone-pair electrons on the sulphur, as determined by photoelectron spectroscopy, has been reported. The effect of substituents on the reactivity of the thiophenoxide ion closely parallels the effect on their basicities. ... 

Compared to the PPP procedure with fixed core parameters, the refined methods do not offer much improvement in the calculation of transition energies or molecular ionization potentials. A similar conclusion was drawn following a comparison of results from different approximations. Zahradnik et al. have shown that the fixed parameter derived in reference 17 also permits discussion of the spectral data of sulphur-containing radicals by open-shell SCF calculation in the Longuet-Higgjns-Pople treatment. 

U.v.-Photoelectron spectra are available for (49)—(52) and diben-zothiophen (55). On the basis of band shapes and PPP calculations, the first three bands have been assigned to -ionization potentials. The good agreement obtained between measured and calculated ionization potentials suggests that sulphur 3d participation must be very small. In contrast, Johnstone et have explained the striking resemblance of the photoelectron spectra of the annelated thiophens to the iso-ir-electronic hydrocarbons naphthalene and anthracene, by the 3d participation of the sulphur atoms. This resemblance is well known, and although the usefulness of the PPP model without d-orbitals has been confirmed, e.g. by calculations of the spectral data of (49)—(53), " of (55) and annelated compounds, " ... 

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