Quantitative Structure-Thermostability Relationship of Late Transition Metal Catalysts in Ethylene Oligo/Polymerization

Abstract

Quantitative structure-thermostability relationship was carried out for four series of bis(imino)pyridine iron (cobalt) complexes and α-diimine nickel complexes systems in ethylene oligo/polymerization. Three structural parameters were correlated with thermal stability, including bond order of metal-nitrogen (B), minimum distance (D) between central metal and ortho-carbon atoms on the aryl moiety and dihedral angle (α) of a central five-membered ring. The variation degree of catalytic activities between optimum and room temperatures (A T ) was calculated to describe the thermal stability of the complex. By multiple linear regression analysis (MLRA), the thermal stability presents good correlation with three structural parameters with the correlation coefficients (R 2 ) over 0.95. Furthermore, the contributions of each parameter were evaluated. Through this work, it is expected to help the design of a late transition metal complex with thermal stability at the molecular level.

Recent advances in thermally robust, late transition metal‐catalyzed olefin polymerization

“…A primary hurdle that remains in this quest is our limited knowledge of the potentially numerous catalyst deactivation and degradation pathways that exist for each catalyst class. Additionally, it is envisioned that the design of future thermally stable late transition metal catalysts may be guided by the use of predictive computational models; preliminary support of which has been provided by Sun and co‐workers …”

“…However, when 15 was activated with diethylaluminium chloride instead of MAO, its activity decreased to 4.87 × 10 5 g (mol Ni) −1 h −1 , highlighting the importance of activator choice and equivalence for many of these late transition metal catalysts. Further insight into this fluorinated class of catalysts was provided by a recent report in which quantum mechanical calculations were used to determine key factors that contribute to the thermal stability of this and other acenaphthenequinone‐derived catalysts . One of those key contributing factors was the bond order from the active metal center to the coordinating nitrogen atoms.…”

Research progress of iron-based catalysts for selective oligomerization of ethylene

“…WenHong Yang et al 64 studied the properties of bis(imine) pyridine ligands and explored the factors affecting the thermal stability of the series ligands during ethylene oligomerization. The molecular structure of the selected ligands is shown in Fig.…”

N , N -chelated nickel catalysts for highly branched polyolefin elastomers: a survey

“…With further increases in the negative electronic effect of the R group and the incorporated F substituent, catalytic performance of complex 9 ( figure 7 ) slightly improved to 1.27 × 10 7 g (PE) mol −1 (Ni) h −1 and produced polyethylene with ultra-high molecular weight [ 110 , 117 , 118 ]. Computational studies on late-transition metal complexes for ethylene polymerization also justify these values of high activities due to the negative electronic effect of substituents and their ultimate effect on the net charge of the active species [ 119 ]. A high number of branches (132 branches per 1000 carbon atoms at 30°C) and narrow molecular-weight distributions are features of the resultant polyethylene.…”