Exploring the first steps of an electrochemically-triggered controlled polymerization sequence: Activation of alkyl- and benzyl halide initiators by an electrogenerated FeIISalen complex.

This works studies the mechanistic features related to the reactions between FeIISalen and several org. halides used as initiators in Atom Transfer Radical Polymn. Within the time scale of cyclic voltammetry, a fast reaction is obsd. between electrogenerated FeIISalen and either Et 2-bromoisobutyrate, CCl4 or 1-chloro-1-phenylethane. Since no catalytic current is obsd. in cyclic voltammetry in the presence of RX, no fast mediated reductive cleavage of RX into R + X- occurred. An intermediate [RXFeSalen] complex was formed which was either relatively stable (Et 2-bromoisobutyrate and 1-chloro-1-phenylethane) or underwent further redn. (CCl4). In the presence of styrene and at 110, polymn. is obsd. and the polydispersity of the resulting polystyrene appears to depend on the FeIIISalen/FeIISalen initial ratio. The role of both FeIIISalen and FeIISalen in the regulation of radical concn. provided a controlled character to the polymn.