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Kinetics of the Oxidative Addition of ortho ‐Substituted Aryl Halides to Palladium(0) Complexes
Author(s) -
Alami Mouad,
Amatore Christian,
Bensalem Samia,
ChoukchouBrahim Abdelharim,
Jutand Anny
Publication year - 2001
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200109)2001:10<2675::aid-ejic2675>3.0.co;2-j
Subject(s) - chemistry , oxidative addition , aryl , steric effects , halide , palladium , medicinal chemistry , oxidative phosphorylation , aryl halide , reactivity (psychology) , stereochemistry , catalysis , organic chemistry , alkyl , biochemistry , medicine , alternative medicine , pathology
The rate constant of the oxidative addition of ortho ‐substituted aryl halides, o ‐ZCH 2 −C 6 H 4 −X [X = I, Br; Z = OMe, NEt 2 , N(CH 2 ) 5 ] to Pd 0 (PPh 3 ) 4 or to Pd 0 (dba)(dppp) generated from Pd 0 (dba) 2 and 1 equiv. of dppp is determined. The oxidative addition is slower for ortho ‐substituted aryl halides than for the corresponding nonsubstituted or meta ‐substituted aryl halides. The ortho substituents investigated here do not participate in the oxidative addition by a preliminary complexation of the active Pd 0 (PPh 3 ) 2 or Pd 0 (dppp) complex. The observed decelerating effect induced by the ortho substituents is due to steric hindrance and electronic donor effects and is less important for aryl bromides than for aryl iodides; ortho ‐substituted aryl iodides remain more reactive than ortho ‐substituted aryl bromides for both ligands PPh 3 and dppp. The cis ‐( o ‐ZCH 2 −C 6 H 4 )PdX(dppp) complexes are formed in the oxidative addition whereas an equilibrium takes place between trans ‐( o ‐ZCH 2 −C 6 H 4 )PdX(PPh 3 ) 2 and ( o ‐ZCH 2 −C 6 H 4 )PdX(PPh 3 )( Z−Pd ) complexes.