Ruthenium(II) Hydrido Complexes of 2,6-(Diphenylphosphinomethyl)pyridine

A series of PNP−ruthenium(II) complexes Ru(OCOMe) 2 (PNP) ( 1 ), Ru(OCOMe) 2 (PNP)(PPh 3 ) ( 2 ), the monohydrides RuHX(PNP)(PPh 3 ) (X = OCOMe ( 3 ); X = Cl ( 4 )), and dihydride RuH 2 (PNP)(PPh 3 ) ( 5 ) (PNP = 2,6-bis(diphenylphosphinomethyl)pyridine) were synthesized and characterized by microanalysis as well as NMR, IR, and mass spectroscopies. The solution dynamics of complex 1 were studied by variable-temperature 1 H and 31 P{ 1 H} NMR spectroscopies. The crystal structure of RuHCl(PNP)(PPh 3 ) ( 4 ) was determined by X-ray crystallography, showing that the PNP ligand coordinates the Ru atom in a meridional mode. The hydrido complexes RuH(OCOMe)(PNP)(PPh 3 ) ( 3 ) and RuH 2 (PNP)(PPh 3 ) ( 5 ) undergo deuterium exchange reactions with CD 3 OD to give substitution of both the hydrides and PNP methylene protons by deuterium. The probable intermediates involved in these exchange processes are molecular dihydrogen complexes of Ru(II).