Synthesis, crystal structure and applications of palladium thiosalicylate complexes

Three palladium thiosalicylate complexes [Pd(tb)(bipy)]·3H2O (1), [Pd2(tb)2(bipy)2]·(dtdb)2 (2) and [Pd2(tb)2(phen)2]·dtdb·H2O (3) (bipy = bipyridine; phen = phenanthroline) were prepared from the reaction of PdCl2(CH3CN)2 with dithiosalicylic acid (dtdb) which underwent cleavage to form thiobenzoate anion (tb) in DMF/MeOH. Square planar geometries of the complexes with a N2SO coordination type were proposed on the basis of single crystal X-ray structural study. The presence of trapped and uncoordinated dtdb was observed in complexes 2 and 3. Complexes 1-3 were evaluated as catalysts for Heck coupling reactions of methyl acrylate with iodobenzene, and showed moderate activities at a very low catalyst loading. Complex 1 was found to inhibit the growth of bacteria and scavenge free radicals efficiently.