Ligand replacement reactions of ferrous phthalocyanine in dimethylsulphoxide: confirmation that both steps can be observed

Reactions of ferrous phthalocyanine with 4-aminopyridine, imidazole or pyri dine in dimethylsulphoxide have been re-investigated using exacting stopped -flow techniques focusing attention on the rapid first stage forming the in termediate FePc(dmso)(base). Effects of impurities in ferrous phthalocyanin e samples formed during storage, and the presence of mu-oxo dimer, on the o bserved kinetic behaviour with base were examined. The correctness of the f indings of an Italian group that kinetic data can be obtained for the first step was affirmed. New results and reassigned published data enabled rate and equilibrium constants to be assigned to the first and second steps for reactions of ferrous phthalocyanine with each of the three nitrogenous base s employed.