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Six examples of newly synthesized α,α'‐bis (aryl)‐2,3:5,6‐bis (pentame thylene)pyridyliron complexes [2,3:5,6‐{C4H8C(NAr)}2C5HN]FeCl2 (Ar = 2‐(c‐C5H9)‐6‐MeC6H3Fe1, 2‐(c‐C6H11)‐6‐MeC6H3Fe2, 2‐(c‐C8H15)‐6‐MeC6H3Fe3, 2‐(c‐C5H9)‐4,6‐Me2C6H2Fe4, 2‐(c‐C6H11)‐4,6‐Me2C6H2Fe5, 2‐(c‐C8H15)‐4,6‐Me2C6H2Fe6; c refers as cyclic), on activation with methylalumoxane (MAO) or modified MAO (MMAO), exhibit high activities towards ethylene polymerization, producing strictly linear polyethylenes with terminal vinyl groups. The catalytic performances are systematically investigated along with various polymerization parameters as well as the microstructures of resultant polyethylenes. The steric hindrances of ortho‐cycloalkyl substituents of Nimino‐aryl groups significantly affect the activities of the corresponding iron precatalysts as well as the microstructures of resultant polyethylenes: higher steric hindrance the ortho‐cycloalkyl substituents, higher activity the iron precatalyst, lower molecular weight the resultant polyethylenes. Experimental observations are additionally supported by the computational study. The resultant polyethylenes exhibited excellent hydrophobicity. [ABSTRACT FROM AUTHOR]

Recent progress concerning the application of compartmentalized bimetallic complexes as homogeneous catalysts in ethylene polymerization is reviewed with particular regard to metal-metal combinations based on either early- (Ti, Zr, Hf and V) or late-transition metals (Fe, Co and Ni). The effect of positioning two polymerization-active metal centers in close proximity on catalytic activity, molecular weight, molecular weight distribution and levels of branching are thoroughly documented. Compartmental ligands comprising binding domains consisting of phenoxyimines, ansa -bridged cyclopentadienyl-amides, α-diimines and iminopyridines are described as is their capacity to serve as compatible binucleating supports for homobimetallic and also for the less investigated heterobimetallic counterparts. By comparison with their mononuclear analogues, any synergic properties exhibited by these binuclear catalysts represents an underlying theme to be developed where possible throughout this review. [ABSTRACT FROM AUTHOR]

ABSTRACT A series of 2-(arylimino)benzylidene-9-arylimino-5,6,7,8-tetrahydrocyclohepta [b]pyridyliron(II) chlorides was synthesized and characterized using FT-IR and elemental analysis, and the molecular structures of complexes Fe3 and Fe4 have been confirmed by the single-crystal X-ray diffraction as a pseudo-square-pyramidal or distorted trigonal-bipyramidal geometry around the iron core. On activation with methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), all iron precatalysts exhibited high activities toward ethylene polymerization with a marvelous thermo-stability and long lifetime. The Fe4/MAO system showed highest activity of 1.56 × 107 gPE·mol−1(Fe)·h−1 at 70 °C, which is one of the highest activities toward ethylene polymerization by iron precatalysts. Even up to 80 °C, Fe3/MAO system still persist high activity as 6.87 × 106 g(PE)·mol−1(Fe)·h−1, demonstrating remarkable thermal stability for industrial polymerizations (80-100 °C). This was mainly attributing to the phenyl modification of the framework of the iron precatalysts. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 830-842 [ABSTRACT FROM AUTHOR]

Six structurally related bis(arylimino)trihydroquinolyl-cobalt (II) chloride complexes [2-(ArN CCH 3)-8-(ArN)-5,6,7-C 9 H 8 N]CoCl 2 (Ar = 2-(C 5 H 9)-6-MeC 6 H 3 Co1 , 2-(C 6 H 11)-6-MeC 6 H 3 Co2 , 2-(C 8 H 15)-6-MeC 6 H 3 Co3 , 2-(C 5 H 9)-4,6-Me 2 C 6 H 2 Co4 , 2-(C 6 H 11)-4,6-Me 2 C 6 H 2 Co5 , 2-(C 8 H 15)-4,6-Me 2 C 6 H 2 Co6), distinguishable by the ring size of the ortho -cycloalkyl substituent and type of para -R group, have been synthesized and characterized. A distorted square pyramidal geometry is a feature of the molecular structure of Co4 with the two ortho -cyclopentyl groups located on neighboring N -aryl groups trans -configured. Compounds Co1 – Co6 , on activation with methylaluminoxane (MAO) or modified MAO (MMAO), proved highly productive catalysts for ethylene polymerization at 60 °C [up to 17.1 × 106 g (PE) mol−1(Co) h−1 for cyclopentyl-containing Co4 /MAO]; even at 90 °C significant activity was attainable (up to 6.75 × 106 g (PE) mol−1(Co) h−1). Strictly linear polyethylene waxes of low molecular weight (ca. 1.50 kg mol−1), narrow dispersity (M w / M n range: 1.1–2.4) and incorporating high levels of vinyl end-groups were generated. Post-functionalization of these PE waxes by epoxidation, thiol-ene addition and cross-olefin metathesis to form e-PE, PE-S-CH 2 CH 2 NH 2 ·HCl and PE-MMA, respectively, has been demonstrated. For comparative purposes, [2-(ArN CCH 3)-8-ArN-5,6,7-C 9 H 8 N]CoCl 2 (Ar = 2,4,6-Me 3 C 6 H 2 Co o -Me , 2-(Ph 2 CH)-4,6-Me 2 C 6 H 2 Co o -CHPh2) have also been prepared and evaluated as polymerization catalysts. Image 1 • Cobalt ethylene polymerization catalysts capable of running at temperatures up to 90 °C. • ortho -Cycloalkyl ring-size variation allows fine control of catalytic performance. • PE waxes with narrow dispersities and high levels of vinyl end-groups are produced. • Amenability of the PE waxes to post-functionalization by epoxidation, thiol-ene addition and cross-olefin metathesis has been demonstrated. • Ready synthesis of catalysts and characteristic vinyl-polyethylenes offer industrial potential. [ABSTRACT FROM AUTHOR]

Five examples of bis(arylimino)tetrahydrocyclohepta[b]pyridine dichloroiron(II) complex, [2-{(Ar)N=CMe}-9-{N(Ar)}C10H10N]FeCl2 (Ar = 2-(C5H9)-4,6-(CHPh2)2C6H2Fe1, 2-(C6H11)-4,6-(CHPh2)2C6H2Fe2, 2-(C8H15)-4,6-(CHPh2)2C6H2Fe3, 2-(C12H23)-4,6-(CHPh2)2C6H2Fe4, and 2,6-(C5H9)2-4-(CHPh2)C6H2Fe5), incorporating ortho-pairings based on either benzhydryl/cycloalkyl (ring sizes ranging from 5 to 12) or cyclopentyl/cyclopentyl groups, have been prepared in reasonable yield by employing a simple one-pot template strategy. Each complex was characterized by FT-IR spectroscopy, elemental analysis, and for Fe3 and Fe5 by single crystal X-ray diffraction; pseudo-square pyramidal geometries are a feature of their coordination spheres. On treatment of Fe1–Fe5 with modified methylaluminoxane (MMAO) or methylaluminoxane (MAO), a range in catalytic activities for ethylene polymerization were observed with benzhydryl/cyclopentyl-containing Fe1/MMAO achieving the maximum level of 15.3 × 106 g PE mol−1 (Fe) h−1 at an operating temperature of 70 °C. As a key trend, the activity was found to drop as the ortho-cycloalkyl ring size increased: Fe1C5H9/CHPh2~Fe5C5H9/C5H9 > Fe2C6H11/CHPh2 > Fe3C8H15/CHPh2 > Fe4C12H23/CHPh2. Furthermore, strictly linear polyethylenes (Tm > 126 °C) were formed with molecular weights again dependent on the ortho-cycloalkyl ring size (up to 55.6 kg mol−1 for Fe1/MAO); narrow dispersities were a characteristic of all the polymers (Mw/Mn range: 2.3–4.7), highlighting the well-controlled nature of these polymerizations. [ABSTRACT FROM AUTHOR]

The unsymmetrical bis (arylimino)pyridines, 2‐[CMeN{2,6‐{(4‐FC6H4)2CH}2–4‐t‐BuC6H2}]‐6‐(CMeNAr)C5H3N (Ar = 2,6‐Me2C6H3L1, 2,6‐Et2C6H3L2, 2,6‐i‐Pr2C6H3L3, 2,4,6‐Me3C6H2L4, 2,6‐Et2–4‐MeC6H2L5), each containing one N‐aryl group bedecked with ortho‐substituted fluorobenzhydryl groups, have been employed in the preparation of the corresponding five‐coordinate cobalt (II) chelates, LCoCl2 (Co1 – Co5); the symmetrical comparator [2,6‐{CMeN(2,6‐(4‐FC6H4)2CH)2–4‐t‐BuC6H2}2C5H3N]CoCl2 (Co6) is also reported. All cobaltous complexes are paramagnetic and have been characterized by 1H/19F NMR spectroscopy, FT‐IR spectroscopy and elemental analysis. The molecular structures of Co3 and Co6 highlight the different degrees of steric protection given to the metal center by the particular N‐aryl group combination. Depending on the aluminoxane co‐catalyst employed to activate the cobalt precatalyst, distinct variations in thermal stability and activity of the catalyst towards ethylene polymerization were exhibited. In particular with MAO, the resultant catalysts reached their optimal performance at 70 °C delivering high activities of up to 10.1 × 106 g PE (mol of Co)−1 h−1 with Co1 > Co4 > Co2 > Co5 > Co3 >> Co6. On the other hand, using MMAO, the catalysts operate most effectively at 30 °C but are by comparison less productive. In general, the polyethylenes were highly linear, narrowly disperse and displayed a wide range of molecular weights [Mw range: 18.5–58.7 kg mol−1 (MAO); 206.1–352.5 kg mol−1 (MMAO)]. [ABSTRACT FROM AUTHOR]