| Abstract
| - Treatment of Cp‘ ‘Zr(C6F5)(OEt2){η5-(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‘){η5-(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-butylisocyanidein toluene at −20 °C leads to the formation of Cp‘ ‘Zr(C6F5)(CNtBu)2{η5-(3-RC4H3BC6F5)}(4H, R = H; 4Me, R = Me), while warming to room temperature results in the insertion ofone molecule of isocyanide into the zirconium−C6F5 bond to give the η2-iminoacyl complexesCp‘ ‘Zr{η2-(C6F5CNtBu)}(CNtBu){η5-(3-RC4H3BC6F5)} (5H, R = H; 5Me, R = Me). Thestructures of 3H and 5H were confirmed by X-ray diffraction. The reaction of the dienecomplexes CpRZr(η3-crotyl)(η4-butadiene) (6a, CpR = C5H4SiMe3; 6b, C5H4Me; 6c, Cp; 6d,Cp‘ ‘) with B(C6F5)3 in toluene solution at room temperature proceeds quantitatively withC−H activation, butene elimination, and C6F5 transfer to generate CpRZr(C6F5){η4-CH2CHCHCHB(C6F5)2} (7a−d). These boryldiene complexes are thermally unstable andsmoothly rearrange to give the triple-decker complexes Zr2(CpR)2(C6F5)2{μ-η5:η5-C4H4BCH2-η3,κF-CHCHCHB(C6F5)3} (8a−d). The formation of these complexes involves the completetransfer of all three C6F5 substituents of one B(C6F5)3 molecule, as well as C−H activationand the loss of one C6F5 group as pentafluorobenzene. The triple-decker complexes featurea Zr2C4B core, a zwitterionic structure, and an unusually strong Zr−F donor interaction.On activation with methylalumoxane (MAO), 8a−d polymerize ethene.
- The reaction of Cp‘ ‘Zr(crotyl)(diene) (Cp‘ ‘ = C5H3(SiMe3)2) with B(C6F5)3 gives mononuclear borole complexes Cp‘ ‘Zr(C6F5)(OEt2){η5-C4H3-3-R-1-B(C6F5)}, which form adducts with donor ligands and insert isocyanides into the Zr−C6F5 bond. By contrast, the reaction of CpRZr(η3-crotyl)(η4-butadiene) (CpR = C5H4SiMe3, C5H4Me, Cp, Cp‘ ‘) with B(C6F5)3 at 40−60 °C gives the triple-decker complexes Zr2(CpR)2(C6F5)2{μ-η5:η5-C4H4BCH2-η3,κF-CHCHCHB(C6F5)3}. Their formation involves the complete transfer of all three C6F5 substituents of one B(C6F5)3 molecule. The compounds polymerize ethene on activation with methylalumoxane.
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