Reaction of B(C6F5)3 with zirconium and hafnium benzyl diene complexes. The crystal and molecular structures of Cp″Zr(C6F5){η4-CH2CMeCHCHB(C6F5)2} and [Cp″Hf(2,3-Me2C4H4)(OEt2)][PhCH2B(C6F5)3] [Cp″ = 1,3-(SiMe3)2C5H3]
- 1 January 1999
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 10,p. 1663-1668
- https://doi.org/10.1039/a901347d
Abstract
The zirconium and hafnium diene complexes Cp″MCl(η4-CH2CMeCR1CH2) react with benzylmagnesium chloride to give the benzyl complexes Cp″M(η4-CH2CMeCR1CH2)(CH2Ph) (M = Zr, R1 = Me or H; M = Hf, R1 = Me) which react with B(C6F5)3 selectively under benzyl abstraction to give the zwitterionic products Cp″M(η4-diene){ηn-PhCH2B(C6F5)3}. The zirconium derivative exists as a mixture of two isomers which interchange via ring-flipping of the diene ligand, whereas the Hf compound is rigid. The isoprene analogue Cp″Zr(CH2CMeCHCH2){PhCH2B(C6F5)3} decomposes at room temperature under C–H activation and C6F5 migration from boron to zirconium to give toluene and the structurally characterised boryldiene complex Cp″Zr(C6F5){CH2CMeCHCHB(C6F5)2}. In the hafnium (but not zirconium) complexes, the [PhCH2B(C6F5)3]– anion is displaced by CH2Cl2. The addition of diethyl ether leads to the ionic compound [Cp″Hf(2,3-Me2C4H4)(OEt2)]+[PhCH2B(C6F5)3] which was characterised by X-ray diffraction.Keywords
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