STRUCTURE AND ELECTRON-DENSITY OF (2,2,2-TRIFLUORO-1-METHYLETHYLIDENE)SULFUR TETRAFLUORIDE, F4S=C(CH3)CF3

High-resolution X-ray data were collected at low temperature (-151 (1)-degrees-C) to determine the crystal and molecular structure and the electron deformation density (EDD) of F4S = C(CH3)(CF3. Crystal data is as follows: a = 1709.0 (7), b = 647.8 (6), c = 1698.0 (7) pm, Beta = 136.96 (6)-degrees, P2(1)/n, Z = 8. The sulfur, the two axial fluorine, and the carbon atoms exhibit a planar arrangement. The equatorial S-F bond distances are significantly shorter than the axial ones. Atomic valence deformations were analyzed in terms of static (SDD) and dynamic deformation densities (DDD) calculated from the fitted multipole populations and X-X Fourier synthesis. The EDD along the S-C bond does not show cylindrical symmetry, i.e., the contours of constant electron density perpendicular to the bond reach out twice as far in the equatorial than in the axial direction. This feature can clearly be attributed to a double bond character. The axial S-F bond appears to be more polarized than the equatorial one. The charge loss at the sulfur atom is shared by the alkylidene and fluorine ligands in a ratio of about 1:2, leading to a polarized S-C bond. In the interpretation of the EDD along the bonds to the F atoms, the proper orientation of the reference density is shown to be useful. To emphasize these bond peaks, the electron density of the promolecule generated with the oriented atom model (OAM) proved itself to be superior to that of the promolecule calculated from spherical atoms.