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Kinetic and Equilibrium Studies of Reactions of N‐Heterocycles with Dimeric and Monomeric Oxorhenium( V ) Complexes
Author(s) -
Espenson James H.,
Nabavizadeh S. Masoud
Publication year - 2003
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/ejic.200200601
Subject(s) - chemistry , quinoline , steric effects , imidazole , medicinal chemistry , stereochemistry , kinetics , monomer , picoline , equilibrium constant , reaction rate constant , pyrimidine , pyridine , organic chemistry , physics , quantum mechanics , polymer
Equilibrium constants have been evaluated for the reaction {MeReO(edt)} 2 + 2 L ⇄ 2 MeReO(edt)L, where edt is 1,2‐ethanedithiolate and L is any of 13 N‐donor heterocyclic ligands. The values of K range from 1.37(27)×10 −2 for pyrimidine to 1.95(6)×10 6 for imidazole at 25 °C in chloroform. A successful correlation of log K with log ( K a ) of HL + was realized except in the case of the 2‐substituted ligands 2‐picoline and quinoline, where steric effects make K smaller than expected from the proton basicity of L. The kinetics of the same reactions were studied; the rate law for the reaction in the forward direction is given by −d[{MeReO(edt)} 2 ]/d t = { k a + k b [L]}[L] × [{MeReO(edt)} 2 ]. Except for 2‐picoline and quinoline, the major pathway is provided by the term that shows the quadratic dependence on [L]. Values of log ( k b ) also correlate with log K , and therefore necessarily with log ( K a ).