A molecular transition metal complex selected from Formula 1: wherein M is zirconium, or hafnium, each independently being in a formal oxidation state of +2, +3, or +4; n is an integer of from 0 to 3, wherein, when n is 0, X is absent; each X is independently a monodentate ligand that is neutral, monoanionic, or dianionic, or two X are taken together to form a bidentate ligand that is neutral, monoanionic, or dianionic; X and n are selected such that the metal-ligand complex is neutral; Z 1 and Z 2 are each -O-; Y is a single atom bridge selected from the following: -CHR-, -CRR'-, -CR 2 -,-CH 2 -, -SiR 2 -, -SiRR'-, -GeR 2 -, -NR-, -CHOR-, -N-NR 2, or -PR-, and wherein each R is independently an alkyl or an aryl, and wherein each R' is independently an alkyl or an aryl; wherein R 1a, R 2a, R 3a, R 4a, R 1b, R 2b, R 3b, R 4b, R 6c, R 7c, R 8c, R 6d, R 7d and R 8d are each, independently, selected from the following: a substituted or unsubstituted (C 1 -C 40)-hydrocarbyl, a substituted or unsubstituted (C 1 -C 40)heterohydrocarbyl, -Si(R C) 3, -OSi(R C) 3, -Ge(R C) 3, -P(R C) 2, -N(R C) 2, -OR C, -SR C, -NO 2, -CN, -CF 3, -OCF 3, -S R C, -S 2 R C, -N=C(R C) 2, -OC R C, -C OR C, -N C R C, -C N(R C) 2, a halogen, or a hydrogen; and wherein each R C is independently a substituted or unsubstituted (C 1 -C 30)hydrocarbyl, or a substituted or unsubstituted (C 1 -C 30) heterohydrocarbyl; and wherein, for Formula 1, two or more of R 1a, R 2a, R 3a, R 4a, R 4a, R 2b, R 3b, R 4a, R 6c, R 7c, R 8c, R 6d, R 7d and R 8d may optionally form one or more ring structures; and wherein either Z 1 or Z 2 is dative covalent (coordinate) to M; wherein the term "substituted hydrocarbyl" refers to a hydrocarbyl in which at least one hydrogen atom is substituted with a substituent that comprises at least one heteroatom; wherein the term "substituted heterohydrocarbyl" refers to a heterohydrocarbyl in which at least one hydrogen atom is substituted with a substituent that comprises at least one heteroatom; and wherein R 5c and R 5d are each, independently, selected from the following groups g1) through g14): wherein M is zirconium, or hafnium, each independently being in a formal oxidation state of +2, +3, or +4; n is an integer of from 0 to 3, wherein, when n is 0, X is absent; each X is independently a monodentate ligand that is neutral, monoanionic, or dianionic, or two X are taken together to form a bidentate ligand that is neutral, monoanionic, or dianionic; X and n are selected such that the metal-ligand complex is neutral; Z 1 and Z 2 are each -O-; Y is a single atom bridge selected from the following: -CHR-, -CRR'-, -CR 2 -,-CH 2 -, -SiR 2 -, -SiRR'-, -GeR 2 -, -NR-, -CHOR-, -N-NR 2, or -PR-, and wherein each R is independently an alkyl or an aryl, and wherein each R' is independently an alkyl or an aryl; wherein R 1a, R 2a, R 3a, R 4a, R 1b, R 2b, R 3b, R 4b, R 6c, R 7c, R 8c, R 6d, R 7d and R 8d are each, independently, selected from the following: a substituted or unsubstituted (C 1 -C 40)-hydrocarbyl, a substituted or unsubstituted (C 1 -C 40)heterohydrocarbyl, -Si(R C) 3, -OSi(R C) 3, -Ge(R C) 3, -P(R C) 2, -N(R C) 2, -OR C, -SR C, -NO 2, -CN, -CF 3, -OCF 3, -S R C, -S 2 R C, -N=C(R C) 2, -OC R C, -C OR C, -N C R C, -C N(R C) 2, a halogen, or a hydrogen; and wherein each R C is independently a substituted or unsubstituted (C 1 -C 30)hydrocarbyl, or a substituted or unsubstituted (C 1 -C 30) heterohydrocarbyl; and wherein, for Formula 1, two or more of R 1a, R 2a, R 3a, R 4a, R 4a, R 2b, R 3b, R 4a, R 6c, R 7c, R 8c, R 6d, R 7d and R 8d may optionally form one or more ring structures; and wherein either Z 1 or Z 2 is dative covalent (coordinate) to M; wherein the term "substituted hydrocarbyl" refers to a hydrocarbyl in which at least one hydrogen atom is substituted with a substituent that comprises at least one heteroatom; wherein the term "substituted heterohydrocarbyl" refers to a heterohydrocarbyl in which at least one hydrogen atom is substituted with a substituent that comprises at least one heteroatom; and wherein R 5c and R 5d are each, independently, selected from the following groups g1) through g14):