2017
DOI: 10.1021/acs.organomet.7b00359
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Highly Regioselective α-Olefin Dimerization Using Zirconium and Hafnium Amine Bis(phenolate) Complexes

Abstract: Five new structural analogues of a previously studied group IV amine bis(phenolate) catalyst, Zr-(ONNEt 2 O)Bn 2 , have been synthesized and tested for oligomerization activity. These structural variations encompass longer alkyl groups, propyl and butyl, on the pendant amine group and two different group IV metals, zirconium and hafnium. Remarkably, all five precatalysts, combined with tris(pentafluorophenyl)borane, oligomerized 1-hexene with almost exclusive selectivity for vinylidene end-groups with a marked… Show more

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Cited by 12 publications
(16 citation statements)
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“…Our study of the catalytic system Cp 2 ZrCl 2 -OAC-MMAO-12 proved the ability of this type of system to dimerize 1-alkenes with high chemoselectivity to give head-to-tail products with a vinylidene moiety > C=CH 2 [5,[9][10][11][12]24,53]. The other Ti subgroup metal compounds, for example, postmetallocene Zr and Hf complexes with [ONNO]-type amine bis(phenolate) ligands, activated by B(C 6 F 5 ) 3 , catalyze the 1-hexene oligomerization with the same regioselectivity [54]. Among these complexes, hafnium catalysts showed the best selectivity towards the dimers (up to 97%); moreover, the molecular weight distribution of the oligomers, obtained in Hf-catalyzed reactions, do not correspond to a typical Schulz−Flory regularity.…”
Section: Discussionmentioning
confidence: 99%
“…Our study of the catalytic system Cp 2 ZrCl 2 -OAC-MMAO-12 proved the ability of this type of system to dimerize 1-alkenes with high chemoselectivity to give head-to-tail products with a vinylidene moiety > C=CH 2 [5,[9][10][11][12]24,53]. The other Ti subgroup metal compounds, for example, postmetallocene Zr and Hf complexes with [ONNO]-type amine bis(phenolate) ligands, activated by B(C 6 F 5 ) 3 , catalyze the 1-hexene oligomerization with the same regioselectivity [54]. Among these complexes, hafnium catalysts showed the best selectivity towards the dimers (up to 97%); moreover, the molecular weight distribution of the oligomers, obtained in Hf-catalyzed reactions, do not correspond to a typical Schulz−Flory regularity.…”
Section: Discussionmentioning
confidence: 99%
“…A number of complexes-namely, WCl 6 /Et 2 AlCl [63], zirconium and hafnium adducts with tetradentate ligand 64 [64], half-sandwich complexes of Ta 65 [65,66] and Co 66 [67], a bis-indenyl complex of Y 67 [68], a zwitter-ionic zirconium complex 69 [54], and a sandwich hydride complex of Sc 68 [69]-were studied in the coordination dimerization of α-olefins (Scheme 4a). In the presence of a WCl 6 -based catalyst, a mixture of vinylidene olefins was formed (Scheme 4b); similar mixtures were obtained in the presence of 65.…”
Section: Dimerization Of α-Olefins Catalyzed By Other Complexes Of Trmentioning
confidence: 99%
“…Thus, the Cp2ZrCl2-XAlBu i 2 (X = H, Bu i ) and [Cp2ZrH2]2-ClAlEt2 systems activated by (Ph3C)[B(C6F5)4] or B(C6F5)3 are able to accomplish selective dimerization and oligomerization of alkenes to give head-to-tail vinylidene products, similarly to systems based on Zr complexes and МАО [3,[6][7][8]13,[57][58][59]. Among the post-metallocene Zr and Hf complexes with [ONNO]-type amino-bis(phenolate) ligands activated by neutral B(C6F5)3, the best selectivity to 1-hexene dimers (up to 97%) was found to hafnium catalysts [60]. Nevertheless, data on the direct participation of metal hydrides in chemo-and regioselective dimerization of alkenes are limited and are mainly concerned with Sc [61], Y [62], Ta [63], and Ru [64] complexes.…”
Section: Study Of 1-hexene Transformations Inmentioning
confidence: 99%
“…Nevertheless, certain issues remain unanswered: how the bis-zirconium structures are activated; what is the principle of formation [3,[6][7][8]13,[57][58][59]. Among the post-metallocene Zr and Hf complexes with [ONNO]-type amino-bis(phenolate) ligands activated by neutral B(C 6 F 5 ) 3 , the best selectivity to 1-hexene dimers (up to 97%) was found to hafnium catalysts [60]. Nevertheless, data on the direct participation of metal hydrides in chemo-and regioselective dimerization of alkenes are limited and are mainly concerned with Sc [61], Y [62], Ta [63], and Ru [64] complexes.…”
Section: Study Of 1-hexene Transformations Inmentioning
confidence: 99%