Modulating co-monomer selectivity using non-covalent dispersion interactions in group 4 olefin polymerization catalysts

A method for designing a Group 4 metallocene olefin polymerization catalyst, the method comprising:

• (a) selecting a first metallocene catalyst framework comprising a Group 4 metal bonded to a hydrocarbyl ligand and to one or two independently selected substituted or unsubstituted η5-cycloalkadienyl ligands, and generating a first ground state model structure (GSA) derived from the first metallocene catalyst framework;
• (b) generating (1) a first transition state model structure (TSA1) derived from migratory insertion of an ethylene molecule into a metal-hydrocarbyl ligand bond of the first metallocene catalyst framework and (2) a second transition state model structure (TSA2) derived from migratory insertion of an α-olefin co-monomer molecule into the metal-hydrocarbyl ligand bond of the first metallocene catalyst framework;
• (c) determining, by at least one processor of a device, relative energies of each of the first ground state model structure (GSA), the first transition state model structure (TSA1), a dispersion energy (Disp EA1) associated with TSA1, the second transition state model structure (TSA2), and a dispersion energy (Disp EA2) associated with TSA2, and determining values for ΔG‡A1 (TSA1−GSA), ΔG‡A2 (TSA2−GSA), and ΔΔG‡A (TSA2−TSA1) for migratory insertion of the ethylene molecule versus the α-olefin molecule in the first metallocene catalyst framework;
• (d) determining, by at least one processor of a device, a number of stabilizing, non-covalent (dispersion-type) interactions (NCI) within a distance of from 2.5 Å to 4.0 Å, inclusive, between (1) the ethylene molecule and the substituted or unsubstituted η5-cycloalkadienyl ligands in the first transition state model structure TSA1 (NCIA1), and (2) the α-olefin molecule and the substituted or unsubstituted η5-cycloalkadienyl ligands in the second transition state model structure TSA2 (NCIA2), and difference between the number of these NCI interactions (ΔNCIA);
• (e) repeating steps (a)-(d) using a second metallocene catalyst framework comprising the Group 4 metal bonded to the hydrocarbyl ligand and to the one or two independently selected η5-cycloalkadienyl ligands, wherein at least one of the η5-cycloalkadienyl ligands comprises a first test substituent, and generating a corresponding second ground state model structure (GSB), third transition state model structure (TSB1), and fourth transition state model structure (TSB2), and determining, by at least one processor of a device, relative energies of each of a GSB, TSB1, including a dispersion energy (Disp EB1) associated with TSB1, TSB2, and a dispersion energy (Disp EB2) associated with TSB2, and determining values for ΔG‡B1 (TSB1-GSB), ΔG‡B2 (TSB2-GSB), ΔΔG‡B (TSB2−TSB1) and a number of stabilizing, non-covalent (dispersion-type) interactions in TSB1 (NCIB1) and TSB2 (NCIB2), and difference between the numbers of these NCI interactions (ΔNCIB), for migratory insertion of the ethylene molecule versus the α-olefin molecule in the second metallocene catalyst framework;
• and
• (f) identifying the first test substituent of the second metallocene catalyst framework as (1) enhancing α-olefin co-monomer incorporation into a polyethylene co-polymer relative to the first metallocene catalyst framework when ΔΔG‡B<ΔΔG‡A, when ΔNCIB>ΔNCIA, or a combination thereof, or (2) enhancing ethylene incorporation into a polyethylene co-polymer relative to the first metallocene catalyst framework when ΔΔG‡B>ΔΔG‡A, when ΔNCIB<ΔNCIA, or a combination thereof.

A catalyst system for polymerizing olefins, comprising:

• a Group 4 metallocene olefin polymerization catalyst designed according to a method comprising:
• (a) selecting a first metallocene catalyst framework comprising a Group 4 metal bonded to a hydrocarbyl ligand and to one or two independently selected substituted or unsubstituted η5-cycloalkadienyl ligands, and generating a first ground state model structure (GSA) derived from the first metallocene catalyst framework;
• (b) generating (1) a first transition state model structure (TSA1) derived from migratory insertion of an ethylene molecule into a metal-hydrocarbyl ligand bond of the first metallocene catalyst framework and (2) a second transition state model structure (TSA2) derived from migratory insertion of an α-olefin co-monomer molecule into the metal-hydrocarbyl ligand bond of the first metallocene catalyst framework;
• (c) determining, by at least one processor of a device, relative energies of each of the first ground state model structure (GSA), the first transition state model structure (TSA1), a dispersion energy (Disp EA1) associated with TSA1, the second transition state model structure (TSA2), and a dispersion energy (Disp EA2) associated with TSA2, and determining values for ΔG‡A1 (TSA1−GSA), ΔG‡A2 (TSA1−GSA), ΔΔG‡A (TSA2−TSA1), and an absolute difference in dispersion energies |ΔDisp EA| calculated as |Δ(Disp EA2−Disp EA1)| for migratory insertion of the ethylene molecule versus the α-olefin co-monomer molecule in the first metallocene catalyst framework;
• (d) repeating steps (a)-(c) using a second metallocene catalyst framework comprising the Group 4 metal bonded to the hydrocarbyl ligand and to the one or two independently selected η5-cycloalkadienyl ligands, wherein at least one of the η5-cycloalkadienyl ligands comprises a first test substituent, and generating a corresponding second ground state model structure (GSB), third transition state model structure (TSB1), and fourth transition state model structure (TSB2), and determining, by at least one processor of a device, relative energies of each of a GSB, TSB1, a dispersion energy (Disp EB1) associated with TSB1, TSB2, and a dispersion energy (Disp EB2) associated with TSB2, and determining values for ΔG‡B1 (TSB1-GSB), ΔG‡B2 (TSB2-GSB), ΔΔG‡B (TSB2−TSB1), and an absolute difference in dispersion energies |ΔDisp EB| calculated as |Δ(Disp EB2−Disp EB1)| for migratory insertion of the ethylene molecule versus the α-olefin co-monomer molecule in the second metallocene catalyst framework;
• and
• (e) identifying the first test substituent of the second metallocene catalyst framework as (1) enhancing α-olefin co-monomer incorporation into a polyethylene co-polymer relative to the first metallocene catalyst framework when ΔΔG‡B<ΔΔG‡A, when |ΔDisp EB|>|ΔDisp EA|, or a combination thereof, or (2) enhancing ethylene incorporation into a polyethylene co-polymer relative to the first metallocene catalyst framework when ΔΔG‡B>ΔΔG‡A, when |ΔDisp EB|<|ΔDisp EA|, or a combination thereof;
• wherein the Group 4 metal is bonded to the hydrocarbyl ligand and to the one or two independently selected substituted or unsubstituted η5-cycloalkadienyl ligands;
• wherein at least one of the η5-cycloalkadienyl ligands comprises the first test substituent which is identified as enhancing olefin co-monomer incorporation into a polyethylene co-polymer, relative to an olefin co-monomer incorporation of the first metallocene catalyst framework, and
• wherein the first metallocene catalyst framework comprises the following structure: