Functionalized Bis(triazolyl)phenylmethanol–palladium(II) Catalysts for Cross Coupling Reactions in Water

Pd^II-bis(triazolyl)phenylmethanol complexes bearing different groups (i. e., H, OMe, OH, COOH) directly attached to the benzyl rings were explored as precatalysts for copper-free Sonogashira and Suzuki–Miyaura coupling reactions in water. Crystal structures reveal a bidentate N,N binding mode of the bis(triazolyl) ligands affording a distorted square planar Pd^II complexes. With the exception of the phenol-substituted bis(triazolyl) ligands, the other three Pd complexes exhibited high activities toward Suzuki–Miyaura coupling reactions. Transmission electron microscopy (TEM) study and PPh₃ poisoning experiments confirm that bis(triazoly)-stabilized Pd nanoparticles (Pd NPs) were generated in situ during the catalytic reactions and involved as one of the active catalytic species in the Suzuki–Miyaura cross coupling.