Ruthenium diphosphine complexes as an efficient hydroamination catalyst

Ruthenium-catalyzed hydroamination of alkenes and alkynes with substituted anilines in the presence of various phosphine ligands have been investigated and catalyst activity and selectivity is improved. Ruthenium(II) complexes of diphenylphosphinomethane, diphenylphosphinoethane, diphenylphosphinopropane, diphenylphosphinobutane and diphenylphosphinopentane showed 50-90 % conversion under mild conditions. The effect of diphosphine ligands, substituent groups on anilines and reaction condition on the selectivity of hydroamination reaction were studied and the possible reaction mechanism was discussed. The reaction products were monitored by GC-MS and a mechanism for the hydroamination of alkenes and alkynes by ruthenium diphosphine complexes was proposed and discussed. The structures of two new complexes, C49H58Cl4P2Ru2 and C35H36Cl2P2Ru, as hydroamination catalysts were determined by X-ray crystallography.