Adducts of antimony(V) pentachloride with neutral lewis bases. Part II. Kinetics and reaction mechanism: a variable temperature and variable pressure proton NMR study

Abstract

The ligand exchange reaction SbCl 5·L + *L⇌ SbCl 5· *L + L has been studied in CH 2Cl 2 and (CHCl 2) 2 as a function of temperature and of pressure by using 1H NMR. First order rate laws, positive activation entropies ranging from +9.8 to +37.3 cal K −1 mol −1, positive activation volumes from +18.2 to +30.0 cm 3 mol −1 and a linear free energy relationship of slope -1.09 ± 0.06 have been observed for a series of L including nitriles, ethers, amides and -PO donor ligands. It is concluded that a limiting dissociative, D, mechanism exists for the whole series of ligand exchange reactions studied.