Dirk Röttger

Reaction of dimethylzirconocene with imidazole in the presence of tris(pentafluorophenyl)borane

Abstract Dimethylzirconocene ( 1 ) reacts with the imidazole · B(C 6 F 5 ) 3 adduct ( 2 ) to give methane and the methylzirconocene/imidazole/ tris(pentafluorophenyl)borane-betaine complex 3 . Subsequent stoichiometric hydrolysis yields the corresponding dinuclear μ-hydroxy-bridged betaine complex 4 , that was characterized by an X-ray crystal structure analysis.

Hydride abstraction from (η2-acetaldehyde) zirconocene dimer using B(C6F5)3

B(C6F5)3 reacts with the (η2-acetaldehyde)zirconocene dimer (4) by hydride transfer from the methyl group of a CH3 CHO ligand to boron. One of the metallaoxirane moieties of the dizirconium complex is then opened to give the salt [(η2-CH3CHO)ZrCp2· (H2C = CHO)ZrCp2]+[HB(C6F5)3]−(6) that was isolated with an 80% yield.

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

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 actions [(Cp2Zr)2(μ-Cl)(μ-η1: 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).