B(C6F5)3 as C6F5 Transfer Agent in Zirconium Chemistry: Borole Sandwich and Borole-Bridged Triple-Decker Complexes

Woodman, TJ, Thornton-Pett, M, Hughes, DL and Bochmann, M (2001) B(C6F5)3 as C6F5 Transfer Agent in Zirconium Chemistry: Borole Sandwich and Borole-Bridged Triple-Decker Complexes. Organometallics, 20 (19). pp. 4080-4091.

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Abstract

Treatment of Cp‘‘Zr(C6F5)(OEt2){?5-(3-RC4H3BC6F5)} ( 1H , R = H; 1Me , R = Me; Cp‘‘ = 1,3-C5H3(SiMe3)2) in toluene with nitriles R‘CN gives rise to the adducts Cp‘‘Zr(C6F5)(NCR‘){?5-(3-RC4H3BC6F5)} ( 2H , R = H, R‘ = Me; 3H , R = H, R‘ = tBu; 3Me , R = Me, R‘ = tBu) in high yields. The reaction of 1H and 1Me with a 4-fold excess of tert-butylisocyanide in toluene at -20 °C leads to the formation of Cp‘‘Zr(C6F5)(CNtBu)2{?5-(3-RC4H3BC6F5)} ( 4H , R = H; 4Me , R = Me), while warming to room temperature results in the insertion of one molecule of isocyanide into the zirconium-C6F5 bond to give the ?2-iminoacyl complexes Cp‘‘Zr{?2-(C6F5CNtBu)}(CNtBu){?5-(3-RC4H3BC6F5)} ( 5H , R = H; 5Me , R = Me). The structures of 3H and 5H were confirmed by X-ray diffraction. The reaction of the diene complexes CpRZr(?3-crotyl)(?4-butadiene) ( 6a , CpR = C5H4SiMe3; 6b , C5H4Me; 6c , Cp; 6d , Cp‘‘) with B(C6F5)3 in toluene solution at room temperature proceeds quantitatively with C-H activation, butene elimination, and C6F5 transfer to generate CpRZr(C6F5){?4-CH2CHCHCHB(C6F5)2} ( 7a - d ). These boryldiene complexes are thermally unstable and smoothly rearrange to give the triple-decker complexes Zr2(CpR)2(C6F5)2{µ-?5:?5-C4H4BCH2-?3,?F-CHCHCHB(C6F5)3} ( 8a - d ). The formation of these complexes involves the complete transfer of all three C6F5 substituents of one B(C6F5)3 molecule, as well as C-H activation and the loss of one C6F5 group as pentafluorobenzene. The triple-decker complexes feature a Zr2C4B core, a zwitterionic structure, and an unusually strong Zr-F donor interaction. On activation with methylalumoxane (MAO), 8a - d polymerize ethene.

Item Type: Article
Faculty \ School: Faculty of Science > School of Chemistry
Related URLs:
Depositing User: Rachel Smith
Date Deposited: 02 Nov 2010 17:48
Last Modified: 24 Jul 2019 17:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/10476
DOI: 10.1021/om010348i

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