Zur Rolle von EDA-Komplexen bei kationischen Polymerisationen. VI[1]. Wechselwirkung von Halogenidionen mit organischen aπ-Elektronenacceptoren

The Role of Donor-Acceptor Complexes in Cationic Polymerisations. The Interaction of Halide Ions with Organic aπ-Acceptors The anions of salts of the type Kat⁺X⁻ (Kat⁺  Li⁺, Na⁺, Et₄N⁺; X⁻  Cl⁻, Br⁻, I⁻) form donor-acceptor complexes with organic a π-acceptors. The long-wave charge-transfer absorption show a bathochrome shift with higher periodic numbers of X⁻ and increasing electron affinity of the acceptors Acc. Strong acceptors form radical ions very rapidly with X  I and slowly with X  Br. Cl. The interactions in the system Kat⁺X⁻ → Acc are influenced by solvents in a very complex way. As acceptors they interact preferably with the halide ion X⁻ and, hence, reduce its donicity for the competing acceptor Acc. As donors they change the dissociation of the ion pair Kat⁺X⁻ by solvation of the cation Kat⁺ and influence in that indirect way also the donicity of X⁻ for the acceptor Acc.