C?Hortho?Pd interactions in palladium complexes derived from tetrasulfur-difluorinated ligands. Experimental, computational and catalytic studies

The symmetric ligands [Ar-S-CH2-Ph-S-(CH2)-]2, L1 (Ar?=?o-FPh) and L2 (Ar?=?p-FPh), and their PdII complexes (1 and 2) were synthesized and structurally characterized. Molecular structures of complexes 1 and 2 display the L1 and L2 ligands coordinating palladium in a ?2-SS bidentate fashion. The metal center exhibits a square planar geometry involving the two sulfur atoms and two chloride atoms which are oriented in cis disposition. Interestingly, the two ortho-hydrogen atoms from the phenyl rings in both complexes are engaged in Pd?Hortho interactions with distances from 2.976 to 3.280?Å. These distances can suffer an increase or decrease in their longitude due to the presence of intramolecular C?H?? interactions. Additionally, the presence of Pd?H interactions in palladium complexes (1 and 2) were identified by an NCI analysis. The complexes 1, 2 and a similar complex 3 that also displays Pd?Hortho interactions have been evaluated in the Suzuki-Miyaura cross-coupling reactions.