A procatalyst according to formula (I): where: M is nickel(II) or palladium(II); X is a ligand chosen from (C 1 -C 40 )hydrocarbyl, (C 1 -C 40 )heterohydrocarbyl, -H, -CH 2 Si(R C ) 3-Q (OR C ) Q , -Si(R C ) 3-Q (OR C ) Q , -OSi(R C ) 3-Q (OR C ) Q , -Ge(R C ) 3-Q (OR C ) Q , -P(R C ) 2-W (OR C ) W , -P(O)(R C ) 2-W (OR C ) W , -N(R C ) 2 , -N(Si(R C ) 3 ) 2 , -NR C Si(R C ) 3 , -OR C , -SR C , -NO 2 , -CN, -CF 3 , -OCF 3 , -S(O)R C , -S(O) 2 R C , -OS(O) 2 R C , -N=C(R C ) 2 , -N=CH(R C ), -N=CH 2 , -N=P(R C ) 3 , -OC(O)R C , -C(O)OR C , -C(O)R C , -C(O)H, -N(R C )C(O)R C , -N(R C )C(O)H, -NHC(O)R C , -NHC(O)H, -C(O)N(R C ) 2 , -C(O)NHR C , -C(O)NH 2 , or a halogen, wherein each R C is independently (C 1 -C 30 )hydrocarbyl optionally substituted with one or more R S or (C 1 -C 30 )heterohydrocarbyl optionally substituted with one or more R S , wherein subscript Q is 0, 1, 2, or 3, and wherein subscript W is 0, 1, or 2; Y is a Lewis base; optionally, Y and X are covalently connected; R 1 is chosen from unsubstituted (C 6 -C 40 )aryl, substituted (C 6 -C 40 )aryl, unsubstituted (C 1 -C 40 )heteroaryl having its radical on a carbon atom, substituted (C 1 -C 40 )heteroaryl having its radical on a carbon atom, or substituted (C 4 -C 20 )alkyl having at least one tertiary carbon atom and its radical on the tertiary carbon atom of the (C 4 -C 20 )alkyl, provided that: R 2 and R 3 are independently selected from radicals having formula (II): where: each R 11 , R 12 , R 13 , R 14 , and R 15 are independently, (C 1 -C 30 )hydrocarbyl, (C 1 -C 30 )heterohydrocarbyl, -OR N , -NR N 2 , -SR N , halogen, or -H, where R N is (C 1 -C 30 )hydrocarbyl; provided that at least one of R 11 and R 15 is not -H; and each R S in formula (I) is independently (C 1 -C 20 )hydrocarbyl or halogen. M is nickel(II) or palladium(II); X is a ligand chosen from (C 1 -C 40 )hydrocarbyl, (C 1 -C 40 )heterohydrocarbyl, -H, -CH 2 Si(R C ) 3-Q (OR C ) Q , -Si(R C ) 3-Q (OR C ) Q , -OSi(R C ) 3-Q (OR C ) Q , -Ge(R C ) 3-Q (OR C ) Q , -P(R C ) 2-W (OR C ) W , -P(O)(R C ) 2-W (OR C ) W , -N(R C ) 2 , -N(Si(R C ) 3 ) 2 , -NR C Si(R C ) 3 , -OR C , -SR C , -NO 2 , -CN, -CF 3 , -OCF 3 , -S(O)R C , -S(O) 2 R C , -OS(O) 2 R C , -N=C(R C ) 2 , -N=CH(R C ), -N=CH 2 , -N=P(R C ) 3 , -OC(O)R C , -C(O)OR C , -C(O)R C , -C(O)H, -N(R C )C(O)R C , -N(R C )C(O)H, -NHC(O)R C , -NHC(O)H, -C(O)N(R C ) 2 , -C(O)NHR C , -C(O)NH 2 , or a halogen, wherein each R C is independently (C 1 -C 30 )hydrocarbyl optionally substituted with one or more R S or (C 1 -C 30 )heterohydrocarbyl optionally substituted with one or more R S , wherein subscript Q is 0, 1, 2, or 3, and wherein subscript W is 0, 1, or 2; Y is a Lewis base; optionally, Y and X are covalently connected; R 1 is chosen from unsubstituted (C 6 -C 40 )aryl, substituted (C 6 -C 40 )aryl, unsubstituted (C 1 -C 40 )heteroaryl having its radical on a carbon atom, substituted (C 1 -C 40 )heteroaryl having its radical on a carbon atom, or substituted (C 4 -C 20 )alkyl having at least one tertiary carbon atom and its radical on the tertiary carbon atom of the (C 4 -C 20 )alkyl, provided that: R 2 and R 3 are independently selected from radicals having formula (II): where: each R 11 , R 12 , R 13 , R 14 , and R 15 are independently, (C 1 -C 30 )hydrocarbyl, (C 1 -C 30 )heterohydrocarbyl, -OR N , -NR N 2 , -SR N , halogen, or -H, where R N is (C 1 -C 30 )hydrocarbyl; provided that at least one of R 11 and R 15 is not -H; and each R S in formula (I) is independently (C 1 -C 20 )hydrocarbyl or halogen. <EOS>