Formation of palladium bis (amine) complexes from reaction of amine with palladium tris(o-tolyl)phosphine mono(amine) complexes

Journal Article (Journal Article)

Palladium mono(benzylamine) complexes Pd[P(o-tolyl) ](p-C H CMe )[H NB ]X (X = Cl (7), Br (8), I (14)) react reversibly with benzylamine in CDCl at 25 °C via P(o-tolyl) displacement to generate the corresponding bis(amine) derivatives trans-Pd(p-C H4CMe )[H -NBn] X (X = Cl (17), K = 0.18 ± 0.02; Br (16), K = 0.14 ± 0.01;I (18), K = 0.10 ± 0.01). Complexes 16-18 were isolated from reaction of the palladium aryl halide dimers {Pd[P(o-tolyl) ](p-C H CMe )(μ-X)} (X = Cl (4), Br (5), I (6)) and excess benzylamine as the corresponding mono(benzylamine) solvate Pd(p-C H CMe )[H NBn] X·H NBn (X = Br (16·H NBn), Cl (17·H NBn), I (18·H NBn)). IR and H NMR spectroscopy of 16·H NBn indicated the presence of N-H⋯X (X = N, Br, Pd) hydrogen bonds in both the solid state and solution. The equilibrium constant for the formation of 16 and P(o-tolyl) from 8 and benzylamine ranged from 0.066 ± 0.005 in CD Cl to 3.6 ± 0.3 in THF-d and in C D ranged from 0.90 ± 0.07 at 25 °C to 0.44 ± 0.04 at 77 °C (ΔG° = 0.06 ± 0.01 kcal mol ; ΔH° =-2.8 ± 0.1 kcal mol ; ΔS° = -9 ± 1 eu). The equilibrium constants for the formation of the bis(amine) complexes Pd(p-C H CMe )[amine] Br from the reaction of Pd[P(o-tolyl) ]-(p-C H Me )[amine] Br and amine decreased in the order phenethylamine ≈ cyclohexylamine ≈ benzylamine ≈ (4-methylbenzyl)amine ≫ piperidine ≫ N-methylbenzylamine. 3 6 4 3 2 n 3 3 6 3 2 2 eq eq eq 3 6 4 3 2 6 4 3 2 2 2 2 2 2 2 3 2 2 8 6 6 298 K 298 K 298 K 6 4 3 2 3 6 4 3 2 1 -1 1

Full Text

Duke Authors

Cited Authors

  • Widenhoefer, RA; Buchwald, SL

Published Date

  • August 6, 1996

Published In

Volume / Issue

  • 15 / 16

Start / End Page

  • 3534 - 3542

International Standard Serial Number (ISSN)

  • 0276-7333

Digital Object Identifier (DOI)

  • 10.1021/om9603169

Citation Source

  • Scopus