83997-79-9Relevant academic research and scientific papers
Stepwise displacement of the tertiary phosphine ligand in square-planar [PdR2L2]-type complexes by organolithium reagents with stereochemical retention affording organopalladate complexes
Nakazawa, Hiroshi,Ozawa, Fumiyuki,Yamamoto, Akio
, p. 241 - 250 (2008/10/08)
Reactions of trans- and cis-[PdR2L2] (R = Me, Et, Ph; L = tertiary phosphine) with R′Li (R′ = Me, Ph) in ether or THF solution lead to stepwise displacement of L by R′ with stereochemical retention to afford alkylpalladate complexes Li[PdR2R′L] and Li2[PdR2R′2], as established by means of 1H, 31P, and 13C NMR spectroscopy. The displacement of PEt3 in trans-[PdPh2(PEt3)2] by MeLi is a slow process, and the rate is independent of the MeLi concentration with indication of a dissociative mechanism generating a three-coordinate, T-shaped intermediate, whereas the reaction of PdR2L2 (R = Me, Et) with MeLi is much faster. Displacement of PEt2Ph in Li[PdMe3(PEt2Ph)] by MeLi is a slow process and first order in concentrations of the complex and MeLi and independent of L. An associative mechanism involving a five-coordinate intermediate is proposed for the second displacement to account for the stereochemical retention. Factors influencing the 1H and 13C NMR chemical shifts of the neutral and palladate complexes are discussed.
