Formation of stable organometallic planar-tetracoordinate carbon compounds containing a cationic ( μ-R1CCR2)[ μ-chloro(ZrCp2)2] framework

Article abstract of DOI:10.1016/0022-328X(96)06208-0

The methylzirconocene cation [Cp₂ZrCH₃(THF)⁺BPh₄^-] reacts with Cp₂Zr(Cl)(C≡C-R) reagents (5a-c, R=-CH₂Ph,-CH₂CH₂CH₃,-CH₃) to yield the dinuclear metallocene cations [(Cp₂Zr)₂(μ-Cl)(μ-η² : η²-RCCCH₃]⁺ (6a-c) (with BPh₄^- anion) that contain a planar-tetracoordinate carbon atom. Complex 6b was characterized by X-ray diffraction. The activation energy of the degenerate rearrangement of 6c was determined by temperature dependent dynamic ₁H NMR spectroscopy (ΔG?(240 K) = 11.3 ± 0.5 kcal mol^-₁).