103903-69-1Relevant articles and documents
Kinetics and mechanism of ortho-palladation of ring-substituted NN-dimethylbenzylamines
Ryabov, Alexander D.,Sakodinskaya, Inna K.,Yatsimirsky, Anatoly K.
, p. 2629 - 2638 (1985)
Addition of excess of NN-dimethylbenzylamine to a chloroform solution of leads to instantaneous depolymerisation of the trimer giving the monomer trans-.Reversible dissociation of the amine from the latter affords a pseudothree-co-ordinate 14-electron intermediate which undergoes subsequent rate-limiting ortho-palladation to form the cyclopalladated acetato-bridged dimer 2>.The rate-limiting step is electrophilic in character; the slope ofthe corresponding Hammett plot for differently ring-substituted NN-dimethylbenzylamines is -1.6.The kinetic isotope effect, kH/kD', for PhCH2NMe2 is 2.2+/-0.2.The activation entropy for the ratelimiting step is very negative, ca. -250 J K-1 mol-1 for PhCH2NMe2, suggesting a highly ordered tight transition state.This dissociative path is a factor of ca. 100 faster than a parallel one, involving the 16-electron monomer trans- but without loss of the amine.Ortho-palladation is not rate-limiting in acetic acid solvent, where slow cleavage of acetate bridges in polynuclear palladium species occurs, affording a vacant co-ordination site for subsequent rapid ortho-palladation.A comparison of intra- and inter-molecular activations of carbon-hydrogen bonds in arenes by palladium(II) in terms of 'effective molarities' shows that the ratio kintra/kinter is not less than 3.6*102 mol dm-3.
