SULFUR K-SHELL PHOTOABSORPTION SPECTROSCOPY OF THE SULFANES R-S-N-R, N=2-4

X-ray absorption near edge structure (XANES) measurements were carried out at the sulfur K-edge of nine sulfanes with the structure R-S-n-R, n = 2-4. The discrete part of the XANES spectra of these sulfanes is expected to be quite similar under the change of the hydrocarbon subst ituents R. However, significant differences were observed in the energ y splitting of the pre-edge resonances as well as in the relative inte nsities of these features. A linear correlation is observed between th e splitting of the sulfur 1s --> sigma(S-C) and 1s --> sigma*(S-S) tr ansitions and the S-C bond length. Similar correlations are expected f or the energy splitting and the S-C bond enthalpy and the difference i n electronegativity between the sulfur atom and the substituent R. We have carried out MS-X alpha calculations on the C-S-S fragment to supp ort the proposed assignment and the parameter dependence of the resona nces mentioned above. (C) 1997 Elsevier Science B.V.