REGIOSELECTIVE HOMOGENEOUS HYDROGENATION OF HETEROAROMATIC NITROGEN-COMPOUNDS BY USE OF [RUH(CO)(NCME)(2)(PPH(3))(2)]BF4 AS THE PRECATALYST

The complex [RuH(CO)(NCMe)(2)(PPh(3))(2)]BF4 (1) is an efficient and r egioselective catalyst precursor for the hydrogenation of polyaromatic nitrogen compounds such as quinoline (Q), isoquinoline (iQ), indole ( In), 5,6- and 7,8-benzoquinoline (BQ) and acridine (A) under relativel y mild reaction conditions (125 degrees C, 4 atm H-2). The order of in dividual initial rates was: A > Q > 5,6-BQ > 7,8-BQ > In > iQ, reflect ing both steric and electronic effects. For the regioselective homogen eous hydrogenation of A to 9,10-dihydroacridine (DHA) catalysed by com plex (1), a kinetic study was carried out, the experimentally determin ed rate law was r = k(1)[Ru] [H-2]. These findings are consistent with a mechanism involving the hydrogenation of [RuH(CO)(A)(NCMe)(PPh(3))( 2)]BF4 to yield DHA and the unsaturated species [RuH(CO)(NCMe)(PPh(3)) (2)]BF4 in the rate-determining step.