The mechanisms and steric course of substitution at a divalent ruthenium centre

Abstract

The thermal rates of substitution of one pyridine group coordinated to the optically active complex cation cis-[Ru phen₂ py₂]²⁺ (phen = o- phenanthroline, py = pyridine) dissolved in dry acetone have been measured using the anions Cl-, Br-, I-, NCS-, N^-₃, and NO^-₂. It was found that for all anions monosubstitution proceeded with complete retention of absolute configuration. The anions Cl-, Br-, I-, and NCS- substituted at a rate which was independent of their nature and concentration. The kinetics of substitution of the anions N^-₃ and NO^-₂ have not been fully resolved, but the rates of reaction of these two anions appear to be faster than the other four.