Catalytic isomerization and disproportionation of olefins promoted by group 4/d0 benzamidinate complexes

Claudia Averbuj, Moris S. Eisen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

56 Scopus citations

Abstract

The group 4/d0 benzamidinate complexes cis-[p-CH3- C6H4C(NSiMe3)2]2Zr(CH3)2 (1), C3-tris([N-trimethylsilyl][N'- myrtanyl]benzamidinate)zirconium chloride (2) and cis-[p- CH3C6H4C(NSiMe3)2]2Ti(CH3)2 (3) were found to be active catalytic precursors, in the presence of MAO (methylalumoxane), for the isomerization of aliphatic olefins (I-octene, 2-E-octene, 3-methyl-1-butene, 2-methyl-1- butene, allylbenzene) and the disproportionation of 1,4- and 1,3- cyclohexadienes. The active species was found to be the cationic hydride complex obtained for aliphatic olefins by the insertion of the methyl ligand with concomitant β-hydrogen elimination, and for the alicyclic dienes by an activation of the allylic hydrogen and accompanying elimination of methane. Kinetic studies and Eyring analysis for the isomerization of allylbenzene show that the reaction is first order in both complex and olefin with ΔH = 17.8(6) kcal · mol-1 and ΔS = -25.1(2) eu. These findings support the epimerization mechanism proposed for these types of cationic complexes, in the polymerization of propylene, toward isotactic polypropylene. To the best of our knowledge, this is the first study in which high oxidation state group 4 complexes are able to induce the catalytic isomerization of olefins or the disproportionation of cyclic olefins.

Original languageEnglish
Pages (from-to)8755-8759
Number of pages5
JournalJournal of the American Chemical Society
Volume121
Issue number38
DOIs
StatePublished - 29 Sep 1999
Externally publishedYes

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