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.