Zur Rolle von EDA-Komplexen bei kationischen Polymerisationen. IV. Untersuchungen an Modellsystemen in Lösung

On the Role of Charge-Transfer Complexes in Cationic Polymerization. IV. Investigation of Model Systems in Solution For the purpose of modelling the influence of donors on the cationic polymerization the complex formation between triphenylmethyl salts of the type (p-R C₆H₄)₃C⁺MtX and aromatic π-and n-donors was investigated. The position of the charge-transfer bands, the equilibrium constants as well as the enthalpies and entropies of complex formation were correlated with the acceptor strength of the cations resp. the basicity of the donors. The complex formation equilibrium was found to be strongly influenced not only by electronic but also steric effects. Strong π-donors like hexamethylbenzene and anthracene as well as n-donors like dialkylethers show a deviating behaviour.