Acyl(furfurylamine)iridium(III) complexes from irida-beta-diketones. Characterisation and catalytic activity in amine-borane hydrolysis

摘要

The irida-beta-diketone [IrHCl{(PPh2(o-C6H4CO))(2)H}] (1) reacts with furfurylamine to afford different products depending on the solvent used. When the reaction is carried out in a THF/H2O mixture [IrH(PPh2(oC(6)H(4)CO))(2)(NH2(CH2)C4H3O-kappa N)] (2) is obtained via dehydrodechlorination and amine-coordination of the ligand. Upon addition of furfurylamine to 1 in methanol, a dehydrogenation reaction leads to [IrCl(PPh2(oC(6)H(4)CO))(2)(NH2(CH2)C4H3O-kappa N)] (3). When the reaction takes place in dry THF a Schiff-base reaction occurs yielding a hydridoirida-beta-ketoimine derivative [IrH(PPh2(o-C6H4CO)(PPh2(o-C6H4C]N(CH2)C4H3O))] (4). All three complexes have been fully NMR characterised and also by single-crystal X-ray diffraction. They have been tested as homogeneous catalysts on the hydrolysis of amine-borane adducts. Complex 2 shows the best results, releasing all 3 equivalents of hydrogen. In situ NMR experiments have been carried out to allow the observation of catalytic intermediates.