GEOMETRIC AND ELECTRONIC-STRUCTURES OF METHYLENE SULFURTETRAFLUORIDE, CH2=SF4, THIONYL TETRAFLUORIDE, O=SF4, AND SULFURTETRAFLUORIDE, SF4 - ABINITIO STUDY

Fully optimized geometric structures for SF4, OSF4, and CH2SF4 have been calculated by the ab initio gradient method. Test calculations for SF4 have indicated that the inclusion of d functions for sulfur is necessary for a quantitative description of its molecular structure. The experimental geometries of SF4 and CH2SF4 are reproduced very well by the calculations. On the basis of the calculations for OSF4, a choice between the four possible molecular models derived from electron diffraction experiments is possible. For CH2SF4, only the conformer with the hydrogen atoms of the methylene group in the axial plane is stable, while the conformer with the hydrogen atoms in the equatorial plane does not correspond to an energy minimum and is about 77 kcal mol-1 above the stable configuration. Variations in the geometry, especially in the bond angles, of the SF4 groups in these three compounds can be rationalized on the basis of the electronic structures. © 1979.