Synthesis of side-chain regioregular and main-chain alternating poly(bichalcogenophene)s and an ABC-type periodic poly(terchalcogenophene).

Three unsymmetrical diiodobichalcogenophenes , , and and a diiodoterchalcogenophene were prepared. Grignard metathesis of , , , and occurred regioselectively at the lighter chalcogenophene site because of its relatively lower electron density and less steric bulk. Nickel-catalyzed Kumada catalyst-transfer polycondensation of these Mg species provided a new class of side-chain regioregular and main-chain AB-type alternating poly(bichalcogenophene)s-, , and -through a chain-growth mechanism.