IRON ARENE COMPLEXES AS FREE-RADICAL AND CATIONIC PHOTOINITIATORS

Evidence is presented that iron (II)-arene complexes can initiate free radical polymerization reactions with low efficiency. Oxygen appears to play a positive role; probably by oxidizing the iron (II) to an iro n (III) species. Cationic curing of an epoxide by an iron-arene comple x was monitored by photodifferential scanning calorimetry and again ox ygen was found to play a positive role. The finding that a decompositi on product of eta6-thioxanthene-eta5-cyclopentadienyliron hexafluoroph osphate is thioxanth-9-one suggests that peroxyl radicals are produced during reaction.