Recent progress in hypervalent organochalcogenuranes bearing four carbon ligands

Abstract

Tetraphenyl- and 2,2′-biphenylylenediphenylsulfuranes and -selenuranes were detected directly by low-temperature NMR experiments. Bis(2,2′-biphenylylene)sulfurane was first isolated as a stable sulfurane having four carbon ligands. Kinetic studies for the ligand coupling reaction of tetraphenylchalcogen compounds Ph 4X (X=S, Se, Te) were monitored by VT- 1 H NMR studies to estimate the activation parameters for these reactions. We also found that the pseudorotations of bis(2,2′-biphenylylene)selenurane and -tellurane take place slowly with respect to the NMR timescale at low temperature. The energy barriers for their pseudorotations were estimated from VT− 13 C NMR studies. Furthermore, theoretical MO studies of chalcogenuranes(IV) bearing four carbon ligands were carried out concerning their structures, Berry pseudorotations, ligand coupling reactions and non-Berry pseudorotations using the tetramethylchalcogenuranes Me 4X (X=S, Se, Te).