Manganese Catalysts with Scorpionate Ligands for Olefin Polymerization

Abstract

The catalyst systems composed of hydrotris-(pyrazolyl)borate (Tp) manganese and coactivators showed good activity for ethylene polymerization and ethylene-R-olefin lymerizations goes up to 1.6 × 10 7 g mol(cat) -1 h -1 , giving ethylene-1-butene copolymer with a narrow molecular weight distribution (M w /M n ) 1.8) and a high melting point (120°C). This system is also active toward propylene and gives isotactic polypropylene with a triad mm fraction of 0.905.Since the discovery of group 4 metallocene single-site catalysts, 1 many efforts have been made for the survey of new transition metal complex catalysts. 2 In particular, Ni-or Pd-based non-metallocene catalysts were the most spectacular breakthroughs in this field. 3 Afterward, many transition metal complex catalysts based on vanadium, 4 chromium, 5 iron and cobalt, 6 and lanthanides 7 have been reported. However, less attention has been paid to group 7 metal catalysts. 8 Mn-based catalysts would be expected to have unique features different from both early and late transition metal catalysts. H. T. Ban and co-workers have reported Mn-(acac) 3 -, Cp 2 Mn-, and Mn(salen)Cl-catalyzed ethylene polymerization when methylaluminoxane (MAO) was used as an activator. 8 In their report, they obtained linear polyethylene having a relatively narrow molecular weight distribution (M w /M n ) 2.8). Among these catalysts, Cp 2 Mn/MAO showed the highest activity of 6.3 kg mol(cat) -1 h -1 , but this level is insufficient for practical use. In this report, we demonstrated three * Corresponding authors.

Manganese(II) halogeno complexes with neutral tris(3,5-diisopropyl-1-pyrazolyl)methane ligand: Synthesis and ethylene polymerization

“…In all cases, the ethylene polymerization activity of a and b activated by TIBA/TB(II) was greater than that activated by MMAO(I). This tendency was the same as the related manganese(II) chloro complex c with the anionic borate ligand [16]. In particular, when MMAO was used as an activator, a negligible weight of polymer was obtained ( Table 1, entries 1 and 3).…”

“…The sterically crowded tris(pyrazolyl)methane ligand L1 was synthesized by the reaction between 3,5-diisopropylpyrazole and CHCl 3 [16,18]. The reaction of L1 with 0.9 equiv.…”

“…Recently, we demonstrated that Mn II -based complexes, [Mn(X)(L3)] (X = Cl, Br, or NO 3 ; L3 − = hydrotris(3-tertiary butyl-5-isopropyl-1-pyrazolyl)borate anion) could compete with the general metallocene catalyst systems, having relatively narrow molecular weight distribution (M w /M n = 1.8) [16]. In this paper, we report syntheses and characterizations of manganese(II) halogeno complexes (a and b) with a neutral tris(3,5-diisopropyl-1-pyrazolyl)methane (HC(3,5-iPr 2 pz) 3 ligand, referred to as L1 ) and the polymerization reaction of ethylene and ethylene/1-hexene under activation conditions, as compared with the related manganese(II) chloro complex (c) with the anionic borate ligand L3 − (Fig.…”

Influences of steric bulkiness in hydrotris(pyrazolyl)borate ligands on ethylene polymerization reaction

“…We developed the manganese(II) based catalysts with N3 tripod hydrotris(pyrazolyl)borate ligands. We have reported that Mn II ‐based complexes, [Mn(L3)(X)] (X = Cl, Br, or NO 3 ; L3 – = hydrotris(3‐tertiary butyl‐5‐isopropyl‐1‐pyrazolyl)borate anion) showed to compete with the general metallocene catalyst systems, having relatively narrow molecular weight distribution ( M w / M n = 1.8),16 and [Mn(L1′)(X) 2 ] (X = Cl or Br; L1′ = tris(3,5‐diisopropyl‐1‐pyrazolyl)methane) displayed better 1‐hexene reactivity of ethylene/1‐hexene copolymerization than [Mn(L3)(X)] 17…”

Transformation of 2-alkoxyimidate-1,10-phenanthroline metal (Mn2+, Co2+ and Ni2+) chlorides from bis(2-cyano-1,10-phenanthroline) metal chlorides: Syntheses, characterizations and their catalytic behavior toward ethylene oligomerization

“…Manganese compounds are frequently used as catalytic precursors in epoxidation of alkenes [19][20][21], oxidation of sulfides [22,23] and hydrocarbons [24,25] as well as various asymmetric reactions [26]. Recently, a few of manganese complexes have also been reported in olefin polymerization [27][28][29][30]. Therefore, the relevant complexes of manganese, cobalt and nickel would be interestingly investigated together.…”