Molecular weight control of polyolefins using halogenated bis-phenylphenoxy catalysts

A process for preparing an olefin homopolymer or copolymer, comprising

• contacting ethylene, an alpha-olefin, or a combination thereof, and a catalytic amount of a metal-ligand complex catalyst of the formula
• wherein M is titanium, zirconium, or hafnium, each independently being in a formal oxidation state of +2, +3, or +4;
• n is an hydrocarbyl;
• (C1-C40)heterohydrocarbyl;
• Si(RC)3, Ge(RC)3, P(RP)2, N(RN)2, ORC, SRC, NO2, CN, F3C, F3CO, RCS(O)—, RCS(O)2—, (RC)2C═N—, RCC(O)O—, RCOC(O)—, RCC(O)N(R)—, (RC)2NC(O)— or halogen atom;
• each of R5c and R5d is independently a (C6-C40)aryl or (C1-C40)heteroaryl;
• and each of the aryl, heteroaryl, hydrocarbyl, heterohydrocarbyl, hydrocarbylene, and heterohydrocarbylene groups is independently unsubstituted or substituted with one or more substituents RS;
• and each RS is independently a halogen atom, polyfluoro substitution, perfluoro substitution, unsubstituted (C1-C18)alkyl, F3C—, FCH2O—, F2HCO—, 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;
• each Z moiety independently is O, S, N(C1-C40) hydrocarbyl, or P(C1-C40) hydrocarbyl;
• L is (C1-C40)hydrocarbylene or (C1-C40)heterohydrocarbylene, provided such has a portion that comprises a 2- to 8-carbon atom linker backbone linking the Z moieties, each atom of such 2- to 8-atom linker being independently a carbon atom or a heteroatom, wherein each heteroatom independently is O, S, S(O), S(O)2, Si(RC)2, Ge(RC)2, P(RP), or N(RN);
• R1a, R1b, or both is a halogen atom;
• and R2a, R3a, R4a, R2b, R3b, R4b, R6c, R7c, R8c, R6d, R7d, and R8d independently is a hydrogen atom;
• (C1-C40) F3CO—, R3Si—, R3Ge—, RO—, RS—, RS(O)—, RS(O)2—, R2P—, R2N—, R2C═N—, NC—, RC(O)O—, ROC(O)—, RC(O)N(R)—, or R2NC(O)—, or two of the RS are taken together to form an unsubstituted (C1-C18)alkylene, wherein each R independently is an unsubstituted (C1-C18)alkyl;.
• under conditions such that an ethylene homopolymer, an alpha-olefin homopolymer, or an ethylene/alpha-olefin copolymer is formed,
• such having a weight average molecular weight that is reduced by at least 20 percent when compared with an otherwise identical ethylene homopolymer, alpha-olefin homopolymer or ethylene/alpha-olefin copolymer prepared under identical conditions with a catalyst that is otherwise identical but wherein neither R1a nor R1b is a halogen atom.