Übergangsmetall‐katalysierte kondensations‐ und polykondensationsreaktionen

While metal‐catalysed polymerizations are chain reaction with constant valence of the metal, metal‐catalysed polycondensations are step polymerizations with changing valence of the metal. Taking as examples the Pd‐catalysed vinyl polymerization of norbornene, the alternating copolymerization of ethylene and carbon monoxide, and the Heck reaction, the essential structural prerequisties of the catalyst to control those reactions are presented. Metal‐catalysed polycondensations may occur as one‐ or two‐electron processes. The oxidative polymerization of 2,6‐dimethylphenol, the Heck reaction, and the Ni‐catalysed polyphenylene synthesis are discussed.