DFT Studies on the Early-Transition-Metal-Catalyzed Polymerization of Polar Monomers with a Methylene Spacer between Vinyl and Functional Groups

Direct (co)­polymerization of polar monomers is the most
economical
and efficient method to prepare functional olefins. However, because
some early-transition-metal catalysts are very sensitive to polar
functional groups due to Lewis acid–base interactions, metal
catalysts are highly sensitive to functional groups of polar monomers.
Thus, (co)­polymerization of polar monomers has been a long-standing
academic research challenge in polymer science, especially for early-transition-metal
complexes. Herein, we computationally demonstrate that the polymerization
of polar monomers with methylene spacers between the vinyl and functional
groups by half-sandwich Ti­(III) and Zr­(III) complexes could be achieved
without any Lewis-acidic masking reagents or bulky protective substituents.
Such a polymerization follows the mechanism of heteroatom-chelating
olefin insertion. We expect that the current results could provide
significant information to propose efficient and accessible early-transition-metal
catalysts for the synthesis of functional polyolefins.