M.C. White. Chem 153 LM Polymerization-307- Week of november 18. 2002 Grubbs,neutral nill polymerization catalyst Unlike heterogeneous Natta and homogeneous cationic metallocer polymerization catal oned by on, and s heteroatom functional eutral Ni(lf) catalyst tolerant of oxygenated functionality. Ethlene polymerizations with 1 can be run in the presence of up to 1500 eq of ether, ketone, and ester additives without significantly inhibiting catalyst activity (-7am) 109C external bath (7 atm) toluene. 10 C external bath Inea Mw>25000 incorporation of polar polymerization catalysts, catalyst 1 monomer: 22 Wgt% produces highly linear PE activity=3.7x 10g PE/mol Ni/r Branch/1000C= 9 >10 branches/1000 C's Mw=73,800 Proposed catalytic cycle The rate of associative displacement of the olefin (leading to chain termination and oligomeric products)may be retarded in these systems(as in the Brookhart system) by the steric H bulk of the ligand which blocks the axial positions above and O PPh3 elow the plane of the Ni complex. The resting state of the styrene, PR catalyst appears to be the phosphine complex(observed by (as in SHOP NMR at various stages throughout the cycle). Neutral Ni(l) complexes are less prone to B-hydride elimination that cationic Ni(l). This may account for the more linear PE bserved in these systems vs the cationic brookhart systems observed byP NMR observed by 3IPNMRM.C. White, Chem 153 LM Polymerization -307- Week of November 18, 2002 Grubbs’neutral Ni(II) polymerization catalyst N O i-Pr NiII Ph i-Pr PPh3 (~7 atm) toluene, 10oC external bath n Mw > 250,000 activity = 3.7x 106 g PE/mol Ni/hr >10 branches/1000 C's linear polyethylene (PE) 1 cat. + (~7 atm) OH toluene, 10oC external bath 1, cat (225 eq.) OH n m incorporation of polar monomer: 22 Wgt % Branch/1000 C = 9 Mw = 73, 800 Unlike heterogeneous Ziegler Natta and homogeneous cationic metallocene polymerization catalysts (poisoned by O,N, and S heteroatom functionality), neutral Ni(II) catalyst 1 is highly tolerant of oxygenated functionality. Ethlene polymerizations with 1 can be run in the presence of up to 1500 eq. of ether, ketone, and ester additives without significantly inhibiting catalyst activity. Unlike the Brookhart cationic Ni(II) polymerization catalysts, catalyst 1 produces highly linear PE. NiII N Ph O PPh3 styrene, PR3 (as in SHOP) NiII N O H NiII N O H NiII N O NiII N O PR3 NiII N O PR3 observed by 31P NMR propagation NiII N O H n NiII N O H n PR3 NiII N O H PR3 observed by 31P NMR n Grubbs Science 2000 (287) 460. Proposed catalytic cycle: The rate of associative displacement of the olefin (leading to chain termination and oligomeric products) may be retarded in these systems (as in the Brookhart system) by the steric bulk of the ligand which blocks the axial positions above and below the plane of the Ni complex. The resting state of the catalyst appears to be the phosphine complex (observed by NMR at various stages throughout the cycle). Neutral Ni(II) complexes are less prone to β-hydride elimination that cationic Ni(II). This may account for the more linear PE observed in these systems vs. the cationic Brookhart systems