The introduction of even a small amount of polar functional groups into polyolefins could excise great control over important material properties. As the most direct and economic strategy, the transition-metal-catalyzed copolymerization of olefins with polar, functionalized monomers represents one of the biggest challenges in this field. The presence of polar monomers usually dramatically reduces the catalytic activity and copolymer molecular weight (to the level of thousands or even hundreds Da), rendering the copolymerization process and the copolymer materials far from ideal for industrial applications. In this contribution, we demonstrate that these obstacles can be addressed through rational catalyst design. Copolymers with highly linear microstructures, high melting temperatures, and very high molecular weights (close to or above 1 000 000 Da) were generated. The direct synthesis of polar functionalized high-molecular-weight polyethylene was thus achieved.

Four manganese carbonyl complexes of the type [MnBr(CO)3(NˆN)] (NˆN = α-diimine ligands) namely [MnBr(CO)3(bpy)] (1), [MnBr(CO)3(phen)] (2), [MnBr(CO)3(dafo)] (3) and [MnBr(CO)3(pyzphen)] (4) (where bpy = bipyridine, phen = 1,10-phenanthroline, dafo = 4,5-diazafluoren-9-one and pyzphen = pyrazino[2,3-f][1,10]-phenanthroline) have been synthesized and structurally characterized. These four complexes containing the fac-[Mn(CO)3] motif release CO upon illumination with low power visible and UV light. The CO release rates and the absorption maxima of the complexes are however very similar despite systematic increase in structural complexity in the rigid α-diimine ligand frames. This is quite in contrary to manganese carbonyl complexes derived from α-diimine ligands in which at least one of the imine functions is not part of the rigid ring systems. Results of this study will provide help in the future design of ligand frames suitable for the syntheses of photoCORMs to deliver CO to biological targets under the control of light.