Heterogenised Rh(I), Ir(I) metal complexes with chiral triaza donor ligands: a cooperative effect between support and complex

Rhodium and iridium complexes of the chiral triaza ligands, {N,N^′-bis{(2S)-(1-benzylpyrrolidinyl)]methyl}amine (2), N,N^′-bis{(2S)-(1-benzylpyrrolidinyl)]methyl}-N-propylamine (3), N,N^′-bis{(2S)-(1-benzylpyrrolidinyl)]methyl}-N-3-(triethoxysilyl)propyl]amine (4)}, are described. All ligands form one to one ML] species with the above metal ions. The structures of these complexes were elucidated by analytical and spectroscopic data (elemental analysis, mass spectroscopy, IR, ¹H and ¹³C NMR). The fixation of the preformed triethoxysilyl-rhodium and iridium complexes, on mesoporous solids (MCM-41, SBA-15), and their use, under heterogeneous conditions, for the hydrogenation reactions are reported. The catalytic activity and selectivity of heterogenised complexes are higher to that observed under homogeneous conditions, as a consequence of the complex- and/or reagents-to-support interaction. The stable covalent bond between support and complex allows the recovery and recycling of the heterogenised catalysts for a number of cycles, moreover atomic absorption analysis of the reaction solutions shows that there is not any metal leaching into the solutions.