KINETICS AND MECHANISM OF THE FORMATION OF PALLADIUM BIS(BENZYLAMINE) COMPLEXES FROM REACTION OF BENZYLAMINE WITH PALLADIUM TRI-O-TOLYLPHOSPHINE MONO(AMINE) COMPLEXES

摘要

The kinetics of the conversion of the palladium mono(benzylamine) complex Pd[P(o-tol)(3)](p-C6H4CMe3)H-2-NBn]Br (2) to the bis(benzylamine) complex Pd(p-C6H4CMe3)[H2NBn](2)Br (3) established the second-order rate law: Rate = k(1)[2][H2NBn], where Delta H-double dagger = 13.8 +/- 0.3 kcal mol(-1) and Delta S-double dagger = -29.7 +/- 0.8 eu. Kinetics were consistent with a mechanism initiated by direct attack of benzylamine on 2 via an associative or interchange mechanism. Benzylamine exchange with both 2 and 3 was > 1.5 x 10(3) times faster than conversion of 2 to 3 under comparable conditions. Complex 2 underwent phosphine exchange in the presence of P(1-naphthyl)(3) to form Pd[P(1-naphthyl)(3)](P-C6H4CMe3)[H2NBn]Br (9). Kinetics of the conversion of 9 to 2 were consistent with associative solvolysis of 9 to form Pd[P(1-naphthyl)(3)](p-C6H4CMe3)[solvent]Br (V) followed by attack of P(o-tolyl)3 to form the mixed bis(phosphine) intermediate Pd[P(o-tol)3][[P(1-naphthyl)(3)](p-C6H4CMe3)Br (VI). Solvolytic displacement of P(o-tolyl)(3) from VI followed by reaction with amine would then form 2. [References: 62]