A catalyst system comprising a metal-ligand complex according to formula (I): where M is a metal chosen from titanium, zirconium, or hafnium, the metal having a formal oxidation state of +2, +3, or +4; each X is a monodentate or bidentate ligand independently chosen from unsaturated (C 2 -C 20 )hydrocarbon, unsaturated (C 2 -C 50 )heterohydrocarbon, (C 1 -C 50 )hydrocarbyl, (C 6 -C 50 )aryl, (C 6 -C 50 )heteroaryl, cyclopentadienyl, substituted cyclopentadienyl, (C 4 -C 12 )diene, halogen, -N(R N ) 2 , and -NCOR C ; n is 1, 2 or 3; m is 1 or 2; the metal-ligand complex has 6 or fewer metal-ligand bonds; each Y is independently selected from oxygen or sulfur; each R 1 , R 2 , R 3 , and R 4 is independently selected from the group consisting of (C 1 -C 50 )hydrocarbyl, (C 1 -C 50 )heterohydrocarbyl, (C 6 -C 50 )aryl, (C 4 -C 50 )heteroaryl, -Si(R C ) 3 , -Ge(R C ) 3 , -P(R P ) 2 , -N(R N ) 2 , -OR C , -SR C , -NO 2 , -CN, -CF 3 , R C S(O)-, R C S(O) 2 -, (R C ) 2 C=N-, R C C(O)O-, R C OC(O)-, R C C(O)N(R)-, (R C ) 2 NC(O)-, halogen, and -H; each R 5 is independently chosen from (C 1 -C 50 )hydrocarbyl, (C 1 -C 50 )heterohydrocarbyl, (C 6 -C 50 )aryl, (C 4 -C 50 )heteroaryl, -Si(R C ) 3 , and -Ge(R C ) 3 , and, when m is 2, two R 5 are optionally covalently linked; for each individual ring containing groups z 1 , z 2 , and z 3 , each of z 1 , z 2 , and z 3 is independently selected from the group consisting of sulfur, oxygen, -N(R R )-, or -C(R R )-, provided that at least one and not more than two of z 1 , z 2 , and z 3 are -C(R R )-, where R R is -H or (C 1 -C 30 )hydrocarbyl, wherein any two R R groups bonded to neighboring atoms are optionally linked; each R C , R N , and R P in formula (I) is independently a (C 1 -C 30 )hydrocarbyl. M is a metal chosen from titanium, zirconium, or hafnium, the metal having a formal oxidation state of +2, +3, or +4; each X is a monodentate or bidentate ligand independently chosen from unsaturated (C 2 -C 20 )hydrocarbon, unsaturated (C 2 -C 50 )heterohydrocarbon, (C 1 -C 50 )hydrocarbyl, (C 6 -C 50 )aryl, (C 6 -C 50 )heteroaryl, cyclopentadienyl, substituted cyclopentadienyl, (C 4 -C 12 )diene, halogen, -N(R N ) 2 , and -NCOR C ; n is 1, 2 or 3; m is 1 or 2; the metal-ligand complex has 6 or fewer metal-ligand bonds; each Y is independently selected from oxygen or sulfur; each R 1 , R 2 , R 3 , and R 4 is independently selected from the group consisting of (C 1 -C 50 )hydrocarbyl, (C 1 -C 50 )heterohydrocarbyl, (C 6 -C 50 )aryl, (C 4 -C 50 )heteroaryl, -Si(R C ) 3 , -Ge(R C ) 3 , -P(R P ) 2 , -N(R N ) 2 , -OR C , -SR C , -NO 2 , -CN, -CF 3 , R C S(O)-, R C S(O) 2 -, (R C ) 2 C=N-, R C C(O)O-, R C OC(O)-, R C C(O)N(R)-, (R C ) 2 NC(O)-, halogen, and -H; each R 5 is independently chosen from (C 1 -C 50 )hydrocarbyl, (C 1 -C 50 )heterohydrocarbyl, (C 6 -C 50 )aryl, (C 4 -C 50 )heteroaryl, -Si(R C ) 3 , and -Ge(R C ) 3 , and, when m is 2, two R 5 are optionally covalently linked; for each individual ring containing groups z 1 , z 2 , and z 3 , each of z 1 , z 2 , and z 3 is independently selected from the group consisting of sulfur, oxygen, -N(R R )-, or -C(R R )-, provided that at least one and not more than two of z 1 , z 2 , and z 3 are -C(R R )-, where R R is -H or (C 1 -C 30 )hydrocarbyl, wherein any two R R groups bonded to neighboring atoms are optionally linked; each R C , R N , and R P in formula (I) is independently a (C 1 -C 30 )hydrocarbyl. <EOS>