Mechanisms of Photolysis of Iron-Arene Cationic Photoinitiators In Different Solvents

Introduction

Polymerization mechanism of epoxy resins photoinitiated by iron
arenecationic-initiators has been proposed by Meier and Zweifel
(ref.l).Photolysis of the iron arene-salts in the presenceof
 monodentate ligands, leads to new complexes of the type3 (ref.2),whereas in pure aprotic solvents, ferrocene and iron salts are' formed (ref.3 and ref.4). The reaction rate of the iron
catalysed polymerization depends upon the nucleophilicityof the
anion employed as well as uponthe. structure of the_epoxy _group.
The_polymerization rate decreases in the order(ref.5).

Iron arene-salts in the presence of an oxidant or radical from
a radical initiator (hybrid systems) may photoinitai.te polymerization of acrylates or acrylic epoxide monomers (ref.6).