Thermally Stable Monosubstituted Thiophene 1-Oxide and 1-Imides Stabilized by a Bulky Rind Group at Their 3-Position: Synthesis, Structure, and Inversion Barriers on the Sulfur Atom

The synthesis and characterization of thermally stable monosubstituted thiophene 1-oxide and 1-imides stabilized by EMind (1,1,7,7-tetraethyl-3,3,5,5-tetramethyl-s-hydrindacen-4-yl) group on the 3-position are described. In addition to the molecular structures determined by X-ray crystallography, inversion barriers at the three-coordinated sulfur atoms have been determined by a coalescence method using diastereotopic C-3 and C-5 indacene carbon atoms as a 13C NMR probe.