Polymerization of Aryl Polyisocyanides Catalyzed by N-Heterocyclic Carbene-Ligated Scandium Trialkyl Complex

Polyisocyanide has attracted continuous attention because of its stable helical rod structure and its wide application, it has a unique π-conjugated system in which the carbon-nitrogen double bond in each unit is twisted along the polymeric backbone to form a helical configuration. In this paper, a series of aryl isocyanides polymers are prepared using N-heterocyclic carbene-ligated scandium trialkyl complex 1 (IPr)Sc(CH2SiMe3)3 as the catalyst and 2 equiv. [Ph3C][B(C6F5)4] as the co-catalyst. The catalyst can convert 96% of 100 equiv. monomer in 5 minutes and the activity of the polymerization can reach 329 kg of polymer molSc-1 h-1. Two optically active polymers are obtained by using chiral monomers, they show strong CD signal at 364 nm and the two signals are opposite.