Nitrile Hydrolysis in a Rhenium(I)-Ruthenium(III) Dinuclear Complex

FAGALDE, FLORENCIA; MELLACE, MARÍA G.; LIS DE KATZ, NOEMÍ D.; KATZ, NÉSTOR E.

JOURNAL OF COORDINATION CHEMISTRY

Taylor & Francis

Lugar: Abingdon; Año: 2004 vol. 57 p. 635 - 639

0095-8972

Kinetic data for the hydrolysis reaction: [(CO)3(bpy)ReI(4-CNpy)RuIII(NH3)5)]4++ H2O ® [(CO)3(bpy)ReI(4-C(O)NHpy)RuIII(NH3)5)]3+ + H+ (bpy = 2,2?-bipyridine, 4-CNpy =4-cyanopyridine and 4-C(O)NHpy = isonicotinamido), that occurs after oxidation with S2O82- of the dinuclear  species [(CO)3(bpy)ReI(4-CNpy)RuII(NH3)5)]3+ , have been obtained in aqueous solutions by spectrophotometric techniques. The observed rate constant, kh = (8.6 ±  0.5) x 10-3 s-1 , at 25 ºC, pH=3.0 (CF3COOH) and I =0.1M (KCl), is ca. 3 times higher than the corresponding one for the mononuclear complex [(4-CNpy)RuIII(NH3)5]3+ , indicating that the catalytic effect of the RuIII(NH3)5 moiety is enhanced by coordination of the free N of 4-CNpy to the ReI(CO)3(bpy) moiety. The value of kh is even higher than that of the dinuclear complex [(trpy)(bpy)RuII(4-CNpy)RuIII(NH3)5]5+ (trpy = 2,2':6',2"-terpyridine), reflecting the fact that carbonyls are much stronger p-acceptors than polypyridines.