Arene complexes radical polymerization

Apart from titanocene initiators, iron arene complexes have also been applied for light-induced radical polymerization, namely of acrylates [202-204]. Iron arene complexes were originally developed for cationic polymerization because they release acid upon irradiation. However, light-induced reactions include the formation of alkyl radicals, which may be utilized for radical initiation. 

Applications of Crown Ethers.—Crown ethers have been found to form molecular complexes with bromine that can be used as reagents in bromination reactions, e.g. of alkenes. The crown-halogen interaction seems not to be encapsulation but rather to be the formation of a polymeric structure. The complexes of nitro-nium tetrafluoroborate (NO2BF4) with various crown ethers, for example the 1 1 complex with 18-crown-6, have been reported to be selective nitrating agents. A new rapid synthesis of alkylseleno- and alkyltelluro-arenes from arenediazon-ium tetrafluoroborates and dialkyl diselenides or ditellurides employs KOAc and 18-crown-6 as a phase-transfer catalyst a radical mechanism has been suggested. Fluorine-19 n.m.r. evidence has been presented to show that KF forms... 

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