Unstoichiometric Suzuki-Miyaura cyclic polymerization of extensively conjugated monomers

Suzuki-Miyaura polycondensation of an excess of linearly extended, conjugated dibromo monomer with meta -phenylenediboronate and of an excess of the extensively conjugated, kinked dibromo monomer with para -phenylenediboronate in the presence of t Bu 3 PPd(0) precatalyst, which has a strong propensity for intramolecular π-face transfer, afforded cyclic polymers with M n 12 400-6400, although unstoichiometric polycondensation generally affords linear polymers. Suzuki-Miyaura polycondensation of an excess of extensively conjugated aromatic dibromide with 1.0 equivalent of phenylenediboronate in the presence of t Bu 3 PPd(0) precatalyst afforded cyclic polymers.