Efficient hydrogenation of ketones and aldehydes catalysed by a well-defined PNNP-rhenium complex.

Well-defined rhenium complexes bearing a tetradentate PNNP ligand were developed for the first time. These new complexes exhibit much better performance in catalytic hydrogenation of carbonyl derivatives into alcohols compared to the corresponding aminophosphine-ligand-constituted complex (o-PPh2C6H4CH2NH2)2Re(CO)2Cl. Under the optimized conditions, the highest turnover frequency and turnover number can be up to 4041 h-1 and 61008, respectively.