The synthesis and characterization of the new Ir(I)-complexes [IrCl(cod)(Bnmim)], [Ir(cod)(emim)(PPh₃)]Cl and [Ir(cod)(Bnmim)(mtppms)] are reported. The zwitterionic complexes [Ir(cod)(NHC)(mtppms)] and Na₂[Ir(cod)(NHC)(mtppts)] (NHC = emim, bmim or Bnmim; mtppms-Na and mtppts-Na₃ = sodium salts of mono- and trisulfonated triphenylphosphine, respectively) were found to be effective precatalysts for transfer hydrogenation of aromatic and aliphatic ketones in basic 2-propanol-water mixtures with initial turnover frequencies up to 510 h⁻¹ at 80 °C, and their catalytic performances were compared to those of [IrCl(cod)(NHC)] complexes (NHC = emim, bmim, Bnmim, IMes) and [Ir(cod)(emim)(PPh₃)]Cl. Three of the catalysts were characterized by single-crystal X-ray diffraction. The reaction rates of the transfer hydrogenation of acetophenone and benzophenone showed strong dependence on the water concentration of the solvent, indicating preferential solvation of the catalytically active metal complexes.

In water/2-propanol mixtures [RhCl(mtppms)(3)] (mtppms = monosulfonated triphenylphosphine) was an efficient catalyst for the selective C=C reduction of trans-3-phenyl-2-propenal (trans-cinnamaldehyde) by hydrogen transfer from formate at temperatures as low as 30 degrees C. An outstandingly high catalyst turnover frequency of 1214 h(-1) was determined at 70 degrees C. A possible mechanism of the reaction is suggested on the basis of kinetic studies and H-1- and P-31-NMR spectroscopic identification of the major Rh(I) species in the reaction mixtures as cis-mer-[H2RhX(mtppms)(3)] (X = HCOO- or H2O). It was established that a large part but not all of the rate increase observed in water/2-propanol mixtures in comparison with systems with neat water as solvent was the consequence of complete dissolution of trans-cinnamaldehyde on the effect of the co-solvent. Nevertheless, the rate showed a significant further increase with increasing 2-propanol concentration even in homogeneous solution and this was ascribed to changes in the solvent structure. The high catalyst activity in this solvent mixture allowed the transfer hydrogenation of citral. Although good to excellent conversions were observed at 30-70 degrees C, a useful degree of selectivity in hydrogenation of C=C vs. C=O bonds could not be achieved.

Water-soluble salan ligands were synthesized by hydrogenation and subsequent sulfonation of salens (N,N’-bis(slicylidene)ethylenediamine and analogues) with various bridging units (linkers) connecting the nitrogen atoms. Pd (II) complexes were obtained in reactions of sulfosalans and [PdCl₄]²⁻. Characterization of the ligands and complexes included extensive X-ray diffraction studies, too. The Pd (II) complexes proved highly active catalysts of the Suzuki–Miyaura reaction of aryl halides and arylboronic acid derivatives at 80 °C in water and air. A comparative study of the Pd (II)–sulfosalan catalysts showed that the catalytic activity largely increased with increasing linker length and with increasing steric congestion around the N donor atoms of the ligands; the highest specific activity was 40,000 (mol substrate) (mol catalyst × h)⁻¹. The substrate scope was explored with the use of the two most active catalysts, containing 1,4-butylene and 1,2-diphenylethylene linkers, respectively.