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A series of water-soluble Rh(i) mononuclear complexes of general formula: [Rh(sulphsal-X-R)(COD)] [sulphsal = sulphonated salicylaldimine, COD = cyclooctadiene; where R = H, Cl, CH3 and X = H, (t)Bu] have been synthesized. All the compounds were characterised using various spectroscopic and analytical techniques such as nuclear magnetic resonance spectroscopy, infrared spectroscopy, single crystal X-ray diffraction (for complex ) and mass spectrometry. All the compounds display excellent water-solubility at room temperature and were tested as catalyst precursors in the aqueous biphasic hydroformylation of 1-octene. The catalysts could be easily recovered by phase separation and were used up to 5 times without any significant loss in activity and 1-octene conversion. Very high yields of the expected aldehydes were obtained without addition of any phase transfer agents, co-solvents or hydrophobic ligands. Excellent aldehyde chemoselectivity is observed for all the catalysts but this varied each time the catalysts were recycled, with the formation of a small amount of internal olefins. ICP-OES and mercury poisoning experiments show that a combination of homogeneous catalysis and catalysis mediated by nanoparticles is taking place in these systems.

n Pr] were prepared, and the electronic effects of co-ligands and alkoxy vs. aminocarbene substituents were investigated by spectroscopic and electrochemical methods. The molecular structures of complexes 1, 2 and 4-6 were confirmed by single crystal X-ray diffraction. The use of the complexes 1-8 as homogeneous catalysts for the hydroformylation of 1-octene was demonstrated, and the influence of the carbene substituents and co-ligands on the activity and regioselectivity of the catalysis evaluated. Finally, the stability of the Rh-Ccarbene bond of complex 1 under hydroformylation conditions was confirmed with 13 C NMR experiments.

Water-soluble mononuclear ruthenium complexes containing monodentate P-donor ligands [1,3,5-triaza-7-phosphaadamantane (PTA) and P(OMe) 3 ], together with a mononuclear bidentate salicylaldimine ruthenium-arene complex, were synthesized from a water-soluble dimeric ruthenium(II)-arene precursor. These complexes were used as catalyst precursors in the aqueous biphasic hydroformylation of 1-octene. Hydroformylation reactions with these Ru-arene complexes showed that the complexes are active hydroformylation catalyst precursors in water. The catalyst precursors convert 1-