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Synthesis, Structure, and Solution Behavior of 1-Chloro-2,2-difluorovinyl Titanocene Derivatives:  The First X-ray Study of a Titanium Fluorovinyl Compound and Spectroscopic Elucidation of the [Cp2TiMe(η2-CF2CClH)] Complex

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posted on 24.05.2004, 00:00 by Nicholas A. Barnes, Alan K. Brisdon, Ian R. Crossley, Robin G. Pritchard, John E. Warren
The first early-transition-metal 1-chloro-2,2-difluorovinyl complexes [Cp2TiXn(CClCF2)2-n] (X = Cl, F; n = 0, 1) have been synthesized by the low-temperature reaction of Cp2TiX2 (X = Cl, F) with (1-chloro-2,2-difluorovinyl)lithum, generated in situ from HCFC-133a (CF3CH2Cl) and n-butyllithium. The complexes have been characterized by spectroscopy and, in the case of [Cp2TiCl(CClCF2)], by single crystal X-ray diffraction, making this the first structurally characterized titanium-based fluorovinyl compound. The marked solution-phase instability of these materials has been explored in an attempt to identify key characteristics that might lead to stabilized systems. To this end, syntheses of the compounds [Cp*2TiFn(CFCF2)2-n] (n = 0, 1) and [Cp2TiMe(CClCF2)] have been reported and their stabilities investigated further. In the case of [Cp2TiMe(CClCF2)], this has led to the spectroscopic characterization of the π-complex [Cp2TiMe(η2-CF2CClH)] as an intermediate in the solution-phase decomposition pathway.