Synthesis and characterization of ruthenium(II) complexes based on diphenyl-2-pyridylphosphine and their applications in transfer hydrogenation of ketones

Synthesis and characterization of the ruthenium complexes [RuH(CO)Cl(κ1-P-PPh2Py)2(PPh3)] (1) and [Ru(CO)Cl2(κ1-P-PPh2Py)(κ2-P–N-PPh2Py)] (2) containing diphenyl-2-pyridylphosphine (PPh2Py) are described. Spectral and structural data suggested linkage of the PPh2Py in κ1-P bonding mode in 1 and both the κ1-P and κ2-P–N bonding modes in 2. The complex 1 reacted with N,N-donor bases viz., ethylenediamine (en), N,N′-dimethyl-(ethylenediamine) (dimen), 1,3-diaminopropane (diap), 2,2′-bipyridine (bipy), 1,10-phenanthroline (phen) and di-2-pyridylaminomethylbenzene (dpa) to afford cationic complexes of formulation [RuH(CO)(κ1-P-PPh2Py)2(N-N)]+ (3–8) [N-N = en, 3; dimen, 4; diap, 5; bipy, 6; phen, 7; and dpa, 8], which have been isolated as their tetrafluoroborate salts. The complexes under investigation have been characterized by elemental analyses, spectroscopic and electrochemical studies. Molecular structures of 2, 3, 6, and 8 have been determined by single crystal X-ray diffraction analyses. Further, the complexes 1–8 act as effective precursor catalyst in transfer hydrogenation of acetophenone/ketones in basic 2-propanol.