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.

New water-soluble, N-heterocyclic carbene (NHC) or mixed NHC/tertiary phosphine complexes [RhCl(cod)(sSIMes)], Na₂[Rh(bmim)(cod)(mtppts)], and [Rh(bmim)(cod)(pta)]BF₄ were synthetized and applied for the first time as catalysts in redox isomerization of allylic alcohols in aqueous media. [RhCl(cod)(sSIMes)] (with added sulfonated triphenylphosphine) and [Rh(bmim)(cod)(pta)]BF₄ catalyzed selectively the transformation of allylic alcohols to the corresponding ketones. The highest catalytic activity, TOF = 152 h⁻¹ (TOF = (mol reacted substrate) × (mol catalyst × time)⁻¹) was observed in redox isomerization of hept-1-en-3-ol ([S]/[cat] = 100). The catalysts were reused in the aqueous phase at least three times, with only modest loss of the catalytic activity and selectivity.

Na₂[Ir(cod)(emim)(mtppts)] (1) with high catalytic activity in various organic- and aqueous-phase hydrogenation reactions was immobilized on several types of commercially available ion-exchange supports. The resulting heterogeneous catalyst was investigated in batch reactions and in an H-Cube flow reactor in the hydrogenation of phenylacetylene, diphenylacetylene, 1-hexyne, and benzylideneacetone. Under proper conditions, the catalyst was highly selective in the hydrogenation of alkynes to alkenes, and demonstrated excellent selectivity in C=C over C=O hydrogenation; furthermore, it displayed remarkable stability. Activity of 1 in hydrogenation of levulinic acid to γ-valerolactone was also assessed.

In aqueous HBr solution (58% w/w), 1,3,5-triaza-7-phosphaadamantane (PTA) yielded the hitherto unknown triprotonated PTA, as single crystals. In addition, the same reaction mixture deposited crystals of [O = P(CH₂NH₃)₃]Br₃ (2), formed presumably by ring opening of [PTA-H₃]Br₃ (3) and oxidation of the resulting [P(CH₂NH₃)₃]Br₃ (1). The solid state structure of 2 and 3 were determined by X-ray diffraction. In water/methanol mixtures, reaction of 1 and [{(η⁶-C₁₀H₁₄)RuBr₂}₂] yielded the half-sandwich [(η⁶-C₁₀H₁₄)RuBr₂{P(CH₂NH₃)₃}]Br₃ (4) which –in aqueous solution– spontaneously afforded the dinuclear [(η⁶-C₁₀H₁₄)RuBr₂{μ⁴-P(CH₂NH₂)₃}Ru(η⁶-C₁₀H₁₄)]Br₂ (5). Graphical Abstract