Room-Temperature Carbon-Sulfur Bond Activation by a Reactive (dippe)Pd Fragment

The reactivity of [Pd(dippe)(mu-H)](2) (1) and [(mu-dippe)Pd](2) (2) (dippe = 1,2-bis(diisopropylphosphino)ethane) toward C-S bonds in thiophene derivatives and thioethers was investigated, which led to C-S bond activation products. The thiapalladacycles derived from thiophenic substrates were fully characterized by H-1, P-31, and C-13 NMR spectroscopy, elemental analysis, and X-ray diffraction. The stability of the C-S insertion products was probed by performing competition experiments which follow the thermodynamic stability order (dippe)Pd(kappa C-2,S-benzothiophene) (6) > (dippe)Pd(kappa C-2,S-dibenzothiophene) (8) > (dippe)Pd(kappa C-2,S-thiophene) (3). The reactivity of the thiapalladacycles with small molecules such as H-2, CO, and alkynes was investigated.