Water-Soluble Palladium(II) Sulfonated Thiosemicarbazone Complexes: Facile Synthesis and Preliminary Catalytic Studies in the Suzuki-Miyaura Cross-Coupling Reaction in Water

A series of mono- and binuclear sulfonated thiosemicarbazone Pd-II complexes have been synthesised and characterised using nuclear magnetic resonance spectroscopy, infrared spectroscopy, electrospray ionisation mass spectrometry and elemental analysis. The complexes display excellent water-solubility at room temperature and in addition, H-1 and P-31{H-1} NMR spectroscopic experiments reveal that the mononuclear complex 4 is very stable in water at 70 degrees C. Consequently, preliminary catalytic experiments show the water-soluble complexes to be efficient catalyst precursors in the Suzuki-Miyaura cross-coupling reaction in water. No evidence of homo-coupling was observed and the water-soluble complexes demonstrated versatility in coupling substrates containing various functional groups.