Synthesis of group 4 complexes that contain the tridentate diamido/donor ligands [(ArylNCH{sub 2}CH{sub 2}){sub 2}O]{sup 2{minus}} and zirconium complexes that contain [(ArylNCH{sub 2}CH{sub 2}){sub 2}S]{sup 2{minus}} and an evaluation of their activity for the polymerization of 1-hexene
- Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Chemistry
Compounds of the type (ArylNHCH{sub 2}CH{sub 2}){sub 2}O (Aryl = 2,6-Me{sub 2}C{sub 6}H{sub 3} (H{sub 2}[1a])), 2,6-Et{sub 2}C{sub 6}H{sub 3} (H{sub 2}[1b]), 2,6-i-Pr{sub 2}C{sub 6}H{sub 3} (h{sub 2}[1c]) can be prepared by treating (TsOCH{sub 2}CH{sub 2}){sub 2}O (TsO = tosylate) with the lithium anilides in THF. [1a,b]TiCl{sub 2}, [1a,b]TiMe{sub 2}, [1a]Ti(CH{sub 2}Ph){sub 2}, [1a-c]M(NMe{sub 2}){sub 2} (M = Zr or Hf), [1a-c]MCl{sub 2}, and [1a-c]MR{sub 2} (R = Me, Et, i-Bu) were prepared. An X-ray study of [1a] Ti(CH{sub 2}Ph){sub 2} revealed the structure to be a distorted trigonal bipyramid (type B) in which the two amido nitrogens and one benzyl ligand occupy equatorial positions. An X-ray study of [1a]ZrMe{sub 2} showed it to be a distorted trigonal bipyramid that contains axial amido groups (type A), while an X-ray study of [1c]HfEt{sub 2} revealed it to have a structure halfway between type A and type B, i.e,, a distorted square pyramid with one alkyl in the apical position. Zr and Hf dimethyl complexes that contain an oxygen donor or a sulfur donor ligand can be activated with [Ph{sub 3}C][B(C{sub 6}F{sub 5}){sub 4}] to yield efficient catalysts for polymerization of 1-hexene, although the molecular weight of the poly(1-hexene) chains is limited to {approximately}20,000-{approximately}25,000 under the conditions employed. Neither {l_brace}[1c]ZrMe(ether){r_brace}[B(C{sub 6}F{sub 5}){sub 4}] nor {l_brace}[1c]HfMe(ether){r_brace}[B(C{sub 6}F{sub 5}){sub 4}] will polymerize 1-hexene in C{sub 6}D{sub 5}Br at room temperature, and neither will polymerize ethylene readily at 1 atm and 25 C. It is proposed that a solvated five-coordinate cation must lose the solvent in order to react with an olefin and that {beta}-hydride elimination in the four-coordinate cation limits chain length.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-86ER13564
- OSTI ID:
- 315973
- Journal Information:
- Organometallics, Vol. 17, Issue 22; Other Information: PBD: 26 Oct 1998
- Country of Publication:
- United States
- Language:
- English
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