72951-34-9Relevant academic research and scientific papers
Dynamic features of the zirconocene-boron-betaine complexes obtained by treatment of bis( alkynyl) zirconocenes with the tris( pentafluorophenyl) borane Lewis-acid
Ahlers, Wolfgang,Temme, Bodo,Erker, Gerhard,Froehlich, Roland,Thomas, Fox
, p. 191 - 201 (1997)
Bis(propynyl)zirconocene (6a) reacts with tris(pentafluorophenyl)borane to yield the carbon-carbon coupled Cp2M( μ-RC4R)B(C6F5)3 betaine product 4a (M = Zr, R = CH3). A variety of differently substituted analogs was prepared (M = Zr, R = n-butyl, phenyl, cyclohexyl; M = Ti, R = CH3; M = Hf; R = CH3, phenyl, SiMe3). These complexes 4 are chiral due to the presence of a rather stable propeller-like R-B(aryl)3 conformation. The activation barrier of the intramolecular enantiomerization process of many examples of this series of complexes was determined by dynamic 1H NMR spectroscopy, with ΔG? values ranging from ca. 13 to 16 kcalmol-1, depending on the substitution pattern. Complex 4a reacts with 2,6-dimethylphenylisocyanide to yield the methylenecyclopropene derivative 1 that was characterized by X-ray diffraction.
