Effect of solvent on reactions of Cp2Zr{(μ-H)2BHR}2 and Cp2ZrH{(μ-H)2BHR} (R = CH3, Ph) with B(C6F5)3

The effect that a solvent has on reactions of Cp2Zr{(μ-H)2BHR}2 and Cp2ZrH{(μ-H)2BHR} (R = CH3, Ph) with B(C6F5)3 has been studied. From the reaction in benzene the metathesis product Cp2Zr{(μ-H)2B(C6F5)2}2, 2, was isolated. In the case of diethyl ether, different hydride abstraction products, including [Cp2Zr(OEt2){(μ-H)2BHPh}][HB(C6F5)3], 3, [Cp2Zr(OEt2){(μ-H)2BHCH3}][HB(C6F5)3], 4, [Cp2Zr(OEt2){(μ-H)2BH2}][HB(C6F5)3], 5, and [Cp2Zr(OEt)(OEt2)][HB(C6F5)3], 6, were isolated depending on the starting zirconocene complex. The diethyl ether molecules of 3–6 are weakly coordinated to Zr and displaced in THF solution. Isolation of 3 and 4 is attributed to their fast precipitation from the reaction mixture, which prevented further reactions from occurring. In addition to the hydride abstraction, a hydride metathesis was also involved in the formation of 5. Time-elapsed 11B NMR studies indicate that 3 and 4 are the intermediates on the pathway to 5 and 6. The molecular structures of 2–6 were determined by single-crystal X-ray diffraction.