A procatalyst comprising a metal-ligand complex according to formula: where: M is hafnium, the metal being in a formal oxidation state of +2, +3, or +4; n is 0, 1, 2, or 3; m is 1 or 2; the metal-ligand complex has 6 or fewer metal-ligand bonds and is overall charge-neutral; each R 1 and each R 2 is independently chosen from (C 1 -C 40)hydrocarbyl, (C 1 -C 40)heterohydrocarbyl, (C 1 -C 40)aryl, (C 1 -C 40)heteroaryl, halogen, and -H, and R 1 and R 2 are optionally covalently linked to each other; when m is 1, each X is a monodentate or bidentate ligand independently selected from the group consisting of (C 1 -C 40)hydrocarbyl, (C 1 -C 40)hydrocarbylene, (C 6 -C 20)aryl, (C 5 -C 20)heteroaryl, cyclopentadienyl, or a substituted cyclopentadienyl, and R 3 is chosen from (C 1 -C 40)hydrocarbyl, (C 5 -C 20)heteroaryl, (C 6 -C 40)aryl, (C 5 -C 40)heteroaryl, unsubstituted (C 1 -C 40)alkyl, or a halogenated phenyl radical and is optionally covalently linked to R 2, provided that when any X is substituted or unsubstituted cyclopentadienyl, R 3 is selected from the group consisting of (C 6 -C 40)aryl substituted with at least one R S and (C 5 -C 40)heteroaryl substituted with at least one R S, where R S is selected from the group consisting of (C 1 -C 40)hydrocarbyl and (C 1 -C 40)heterohydrocarbyl; and; when m is 2, each X is a monodentate or bidentate ligand independently selected from the group consisting of (C 1 -C 40)hydrocarbyl, (C 1 -C 40)hydrocarbylene, (C 6 -C 20)aryl, (C 5 -C 20)heteroaryl, and a substituted or unsubstituted cyclopentadienyl, and each R 3 is independently chosen from (C 1 -C 40)hydrocarbyl, (C 5 -C 20)heteroaryl, (C 6 -C 40)aryl, (C 5 -C 40)heteroaryl, unsubstituted (C 1 -C 40)alkyl, or a halogenated phenyl radical, provided that when no X is a substituted or unsubstituted cyclopentadienyl, R 3 is selected from the group consisting of a (C 6 -C 40)aryl substituted with at least one R S and a (C 5 -C 40)heteroaryl substituted with at least one R S, where R S is selected from the group consisting of (C 1 -C 40)hydrocarbyl and (C 1 -C 40)heterohydrocarbyl. M is hafnium, the metal being in a formal oxidation state of +2, +3, or +4; n is 0, 1, 2, or 3; m is 1 or 2; the metal-ligand complex has 6 or fewer metal-ligand bonds and is overall charge-neutral; each R 1 and each R 2 is independently chosen from (C 1 -C 40)hydrocarbyl, (C 1 -C 40)heterohydrocarbyl, (C 1 -C 40)aryl, (C 1 -C 40)heteroaryl, halogen, and -H, and R 1 and R 2 are optionally covalently linked to each other; when m is 1, each X is a monodentate or bidentate ligand independently selected from the group consisting of (C 1 -C 40)hydrocarbyl, (C 1 -C 40)hydrocarbylene, (C 6 -C 20)aryl, (C 5 -C 20)heteroaryl, cyclopentadienyl, or a substituted cyclopentadienyl, and R 3 is chosen from (C 1 -C 40)hydrocarbyl, (C 5 -C 20)heteroaryl, (C 6 -C 40)aryl, (C 5 -C 40)heteroaryl, unsubstituted (C 1 -C 40)alkyl, or a halogenated phenyl radical and is optionally covalently linked to R 2, provided that when any X is substituted or unsubstituted cyclopentadienyl, R 3 is selected from the group consisting of (C 6 -C 40)aryl substituted with at least one R S and (C 5 -C 40)heteroaryl substituted with at least one R S, where R S is selected from the group consisting of (C 1 -C 40)hydrocarbyl and (C 1 -C 40)heterohydrocarbyl; and; when m is 2, each X is a monodentate or bidentate ligand independently selected from the group consisting of (C 1 -C 40)hydrocarbyl, (C 1 -C 40)hydrocarbylene, (C 6 -C 20)aryl, (C 5 -C 20)heteroaryl, and a substituted or unsubstituted cyclopentadienyl, and each R 3 is independently chosen from (C 1 -C 40)hydrocarbyl, (C 5 -C 20)heteroaryl, (C 6 -C 40)aryl, (C 5 -C 40)heteroaryl, unsubstituted (C 1 -C 40)alkyl, or a halogenated phenyl radical, provided that when no X is a substituted or unsubstituted cyclopentadienyl, R 3 is selected from the group consisting of a (C 6 -C 40)aryl substituted with at least one R S and a (C 5 -C 40)heteroaryl substituted with at least one R S, where R S is selected from the group consisting of (C 1 -C 40)hydrocarbyl and (C 1 -C 40)heterohydrocarbyl.