Dramatic Changes in Geometry after Ionization: Experimental and Theoretical Studies on the Electronic Properties of Fluorocarbonyl (Mono-, Di-, and Tri-) Sulfur Compounds

ERBEN, M. F.; DELLA VÉDOVA, C.O.

INORGANIC CHEMISTRY

American Chemical Society

Año: 2002 vol. 41 p. 3740 - 3748

0020-1669

In this work, we present a complete study on He I photoelectron spectroscopy (PES) for the fluorocarbonyl mono-, di-, and trisulfur compounds FC(O)SCl, FC(O)SSCH3, and FC(O)SSSC(O)F. After optimizations of the structure for stable conformers at different levels of theory, a complete theoretical study involving the calculation of the ionization energies using orbital valence Green’s functional (OVGF) was performed. Calculations of radical-cationic forms were carried out in order to compare their properties with those of the neutral molecules. The first IP values are 10.7, 9.0, and 10.5 eV for FC(O)SCl, FC(O)SSCH3, and FC(O)SSSC(O)F, respectively. The groups bonded to the S atom mainly influence the ionizations originating from the sulfur lone pairs. A wide electronic  elocalization in the FC(O)S moiety can be deduced from experimental and theoretical results, which leads to a strong energetic stabilization of the n¢¢S (sulfur lone pair ð orbital). Other conclusions relate to effects on the substituents attached to the S atom and the importance of the molecular planarity in the orbital stabilization of the FC(O)S moiety for the neutral molecules. It is worthwhile mentioning that FC(O)SCl retains its planar structure after ionization, but drastic changes occur in the geometry of both FC(O)SSCH3 and FC(O)SSSC(O)F. The FC(O)SSCH3 molecule adopts a heavy atom planar structure after ionization. The FC(O)SSS moiety becomes a planar form after the  ionization of the FC(O)SSSC(O)F molecule, whereas the second C(O)F group maintains its original conformation with respect to the SSS group.