Effect of solvent on reactions of Cp 2Zr{(μ-H) 2BHR} 2 and Cp 2ZrH{(μ-H) 2BHR} (R = CH 3, Ph) with B(C 6F 5) 3

Abstract

The effect that a solvent has on reactions of Cp 2Zr{(μ-H) 2BHR} 2 and Cp 2ZrH{(μ-H) 2BHR} (R = CH 3, Ph) with B(C 6F 5) 3 has been studied. From the reaction in benzene the metathesis product Cp 2Zr{(μ-H) 2B(C 6F 5) 2} 2, 2, was isolated. In the case of diethyl ether, different hydride abstraction products, including [Cp 2Zr(OEt 2){(μ-H) 2BHPh}][HB(C 6F 5) 3], 3, [Cp 2Zr(OEt 2){(μ-H) 2BHCH 3}][HB(C 6F 5) 3], 4, [Cp 2Zr(OEt 2){(μ-H) 2BH 2}][HB(C 6F 5) 3], 5, and [Cp 2Zr(OEt)(OEt 2)][HB(C 6F 5) 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.