,-Bis(2,4-Dibenzhydryl-6-cycloalkylphenyl)butane-2,3-diimine-Nickel Complexes as Tunable and Effective Catalysts for High-Molecular-Weight PE Elastomers.

Four examples of ,-bis(aryl)butane-2,3-diimine-nickel(II) bromide complexes, [ArN=C(Me)-C(Me)=NAr]NiBr (where Ar = 2-(CH)-4,6-(CHPh)CH (), Ar = 2-(CH)-4,6-(CHPh)CH (), 2-(CH)-4,6-(CHPh)CH () and 2-(CH)-4,6-(CHPh)CH ()), disparate in the ring size of the -cycloalkyl substituents, were prepared using a straightforward one-pot synthetic method. The molecular structures of and highlight the variation in the steric hindrance of the -cyclohexyl and -cyclododecyl rings exerted on the nickel center, respectively. By employing EtAlCl, EtAlCl or MAO as activators, - displayed moderate to high activity as catalysts for ethylene polymerization, with levels falling in the order (cyclohexyl) > (cyclopentyl) > (cyclododecyl) > (cyclooctyl).

High molecular weight polyethylenes of narrow dispersity promoted using bis(arylimino)cyclohepta[b]pyridine-cobalt catalysts ortho-substituted with benzhydryl & cycloalkyl groups.

A one-pot template strategy has been utilized to synthesize sterically enhanced bis(imino)cyclohepta[b]pyridine-cobalt(ii) chlorides, [2-{(Ar)N[double bond, length as m-dash]CMe}-9-{N(Ar)}C10H10N]CoCl2 (Ar = 2-(C5H9)-4,6-(CHPh2)2C6H2Co1, 2-(C6H11)-4,6-(CHPh2)2C6H2Co2, 2-(C8H15)-4,6-(CHPh2)2C6H2Co3, 2-(C12H23)-4,6-(CHPh2)2C6H2Co4, 2,6-(C5H9)2-4-(CHPh2)C6H2Co5). All five complexes have been characterized by a combination of FT-IR spectroscopy, elemental analysis and single crystal X-ray diffraction. The molecular structures of Co1, Co3 and Co5 highlight the substantial steric hindrance imparted by the 2-cycloalkyl-6-benzhydryl or 2,6-dicyclopentyl ortho-substitution pattern; distorted square pyramidal geometries are exhibited in each case.

Probing the effect of ortho-cycloalkyl ring size on activity and thermostability in cycloheptyl-fused N,N,N-iron ethylene polymerization catalysts.

The syntheses of six bis(imino)-5,6,7,8-tetrahydrocycloheptapyridine-iron(ii) chloride complexes, [2-{(Ar)NCMe}-9-{N(Ar)}CHN]FeCl (Ar = 2-(CH)-6-MeCHFe1, 2-(CH)-6-MeCHFe2, 2-(CH)-6-MeCHFe3, 2-(CH)-4,6-MeCHFe4, 2-(CH)-4,6-MeCHFe5, 2-(CH)-4,6-MeCHFe6), are reported in which the ring size of the ortho-cycloalkyl group has been varied as has the type of para-substituent. The molecular structures of Fe3 and Fe6 reveal square pyramidal geometries at iron while the ortho-cyclooctyl rings adopt boat-chair conformations. On treatment with either methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), all six complexes showed optimal activities at 80 °C [up to 1.

Highly Linear Polyethylenes Achieved Using Thermo-Stable and Efficient Cobalt Precatalysts Bearing Carbocyclic-Fused -Pincer Ligand.

Six examples of 2-(1-arylimino)ethyl-9-arylimino-5,6,7,8-tetrahydrocycloheptapyridine-cobalt(II) chloride complexes, [2-(1-ArN)C₂H₃-9-ArN-5,6,7,8-C₅H₈C₅H₃N]CoCl₂, (Ar = 2-(C₅H₉)-6-MeC₆H₃ , 2-(C₆H)-6-MeC₆H₃ , 2-(C₈H)-6-MeC₆H₃ , 2-(C₅H₉)-4,6-Me₂C₆H₂ , 2-(C₆H)-4,6-Me₂C₆H₂ , and 2-(C₈H)-4,6-Me₂C₆H₂ ), were synthesized by the direct reaction of the corresponding -cycloalkyl substituted carbocyclic-fused bis(arylimino)pyridines (⁻) and cobalt(II) chloride in ethanol with good yields. All the synthesized ligands (⁻) and their corresponding cobalt complexes (⁻) were fully characterized by FT-IR, ¹H/C-NMR spectroscopy and elemental analysis. The crystal structure of and revealed that the ring puckering of both the -cyclohexyl/cyclooctyl substituents and the one pyridine-fused seven-membered ring; a square-based pyramidal geometry is conferred around the metal center.

ortho-Cycloalkyl substituted N,N'-diaryliminoacenaphthene-Ni(ii) catalysts for polyethylene elastomers; exploring ring size and temperature effects.

A family of six unsymmetrical N,N'-diiminoacenaphthene-nickel(ii) bromide complexes, [1-{2,6-(PhCH)-4-MeCHN}-2-(ArN)CCH]NiBr (Ar = 2-(CH)-6-MeCHNi1, 2-(CH)-6-MeCHNi2, 2-(CH)-6-MeCHNi3, 2-(CH)-4,6-MeCHNi4, 2-(CH)-4,6-MeCHNi5, 2-(CH)-4,6-MeCHNi6), each bearing one ring-size variable 4-R-2-methyl-6-cycloalkyl-substituted N-aryl group and one N'-4-methyl-2,6-dibenzhydrylphenyl group, have been prepared and fully characterized. The molecular structures of Ni1, Ni2, Ni3 and Ni5 reveal distorted tetrahedral geometries with different degrees of steric protection imparted by the two inequivalent N-aryl groups. On activation with either EASC or MMAO, all the precatalysts are highly active (up to 17.