Early Transition Metal Complexes Bearing a C-Capped Tris(phenolate) Ligand Incorporating a Pendant Imine Arm: Synthesis, Structure, and Ethylene Polymerization Behavior

Homden, D, Redshaw, C, Wright, JA, Hughes, DL and Elsegood, MRJ. (2008) Early Transition Metal Complexes Bearing a C-Capped Tris(phenolate) Ligand Incorporating a Pendant Imine Arm: Synthesis, Structure, and Ethylene Polymerization Behavior. Inorganic Chemistry, 47 (13). pp. 5799-5814.

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Abstract

The ligand 3-[2,2'-methylenebis(4,6-di-tert-butylphenol)-5-tert-butylsalicylidene-(2,6-diisopropyl)phenylimine] (L 1 H3) was reacted with MCl4 (M = Ti, Zr) or MCl5 (M = Nb, Ta) to give complexes of the type [MCl2( L 1 H2)2] (M = Ti ( 1 ); Zr ( 2 )), [NbCl3( L 1 H)] ( 3 ), or [TaCl4( L 1 H2)] ( 4 ), respectively. Single crystal X-ray diffraction of 1 - 4 revealed common “iminium” species resulting in zwitterionic complexes. Reaction of [V(Np-tol)(On-Pr)3] with L 1 H3 afforded [{(VNp-tol)( L 1 H)}2(µ-On-Pr)2] ( 5 ), and a second complex [(VO)2(µ-O)( L 3 H)2] ( 6 ) ( L 3H being derived from 3-[2,2'-methylenebis(4,6-di-tert-butylphenol)-5-tert-butylsalicylidene-p-tolylimine]). The condensation reaction between 3-[2,2'-methylenebis(4,6-di-tert-butylphenol)-5-tert-butyl-2-hydroxybenzaldehyde] ( L 0 H3) and o-phenylenediamine (1,2-diaminobenzene) afforded two products: a pseudo-16-membered hydrogen bonded macrocyclic structure {1,2-bis-3-[2,2'-methylenebis(4,6-di-tert-butylphenol)-5-tert-butylsalicylidene-benzyldiimine]} ( L 5 H6), or the benzimidazolyl bearing ligand ( L 6 H3). The reaction of L 5 H6 or L 6 H3 with [VO(On-Pr)3] under varying conditions produced the complexes [(VO)( L 5 H4)] ( 7 ), [(VO)2( L 5 H)] ( 8 ), or [VO( L 6 H2)2] ( 9 ). L 0 H3 was reacted with a number of anilines to give the proligands {3-[2,2'-methylenebis(4,6-di-tert-butylphenol)-5-tert-butylsalicylidene-R-imine]}, where R = NC6H5 ( L 2 H3), NC6H4-Me ( L 3 H3), and NC6H2-Me3 ( L 4 H3). Reactions of these ligands with [VO(On-Pr)3] formed bischelating complexes of the form [(VO)( L 2-4 H2)2] ( 10 , 11 , and 12 , respectively). The reaction of L 1 H3 with trimethylaluminum led to a bis-aluminum complex {(AlMe2)[AlMe(NCMe)] L 1 } ( 13 ). The ability of complexes 1-12 to polymerize ethylene in the presence of an organoaluminum cocatalyst was investigated. Procatalysts 1 and 2 were found to produce negligible activities in the presence of dimethylaluminum chloride (DMAC) and the reactivator ethyltrichloroacetate (ETA), whereas 3 and 4 were found to be completely inactive for polymerization using a variety of different organoaluminum cocatalysts. Using the combination of DMAC and ETA, complexes 5-12 were found to be highly active catalysts; in all cases, the polymer formed was of high molecular weight linear polyethylene.

Item Type: Article
Faculty \ School: Faculty of Science > School of Chemistry
Related URLs:
Depositing User: Rachel Smith
Date Deposited: 24 Mar 2011 15:39
Last Modified: 17 Mar 2020 15:58
URI: https://ueaeprints.uea.ac.uk/id/eprint/27146
DOI: 10.1021/ic702506w

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