KINETICS AND MECHANISMS OF THE LIGAND SUBSTITUTION-REACTIONS OF AMINE)(CYCLOBUTANE-1,1-DICARBOXYLATO)PALLADIUM(II)

Kinetic and mechanistic investigations have been made on the displacem ent of the bidentate cyclobutane-1,1-dicarboxylate ligand (cbdca) from the complexes [Pd(en)(cbdca)] (en = ethane-1,2-diamine) and [Pd(bpy)( cbdca)] (bpy = 2,2'-bipyridine). Two consecutive reaction steps were o bserved for the substitution of cbdca with thiourea (tu), tetramethylt hiourea (tmtu), inosine 5'-monophosphate (5'-IMP) and iodide, as well as for the acid-catalysed hydrolysis reaction. After displacement of c bdca by tu and tmtu the strong trans influence of the Pd-bound sulfur- containing nucleophiles resulted in displacement of the en ligand from [Pd(en)(cbdca)], whereas no such reaction was found to occur for [Pd( bpy)(cbdca)]. Ail rate and activation parameters are consistent with a ssociative substitution mechanisms.