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

The first early-transition-metal 1-chloro-2,2-difluorovinyl complexes [Cp₂TiX_n(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*₂TiF_n(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.