Disproportionation of Cationic Zirconium Complexes: A Possible Pathway to the Deactivation of Catalytic Cationic Systems
摘要:
Protonolysis of the zirconium borohydride [(C5H4R)(2)Zr(BH4)(2)] (R = H, Me, SiMe3) with NHMe2PhBPh4 in THF leads to the corresponding cationic zirconium complex [(C5H4R)(2)Zr(BH4)(THF)]BPh4, and the structure of [(C5H4Me)(2)Zr(BH4)(THF)]BPh4 was determined. In the presence of phosphine, PMe2Ph, the formation of the cationic hydride [(C5H4R)(2)ZrH(PMe2Ph)(2)]BPh4 is observed by H-1 and P-31 NMR followed by a disproportionation and a redox reaction with [BPh4](-), giving the neutral [(C5H4R)(2)ZrH(mu-H)](2) and the cationic Zr-III species [(C5H4R)(2)Zr(PMe2Ph)(2)]BPh4 characterized by EPR spectroscopy and suggesting a probable pathway in the deactivation of cationic catalyst systems.
Disproportionation of Cationic Zirconium Complexes: A Possible Pathway to the Deactivation of Catalytic Cationic Systems
摘要:
Protonolysis of the zirconium borohydride [(C5H4R)(2)Zr(BH4)(2)] (R = H, Me, SiMe3) with NHMe2PhBPh4 in THF leads to the corresponding cationic zirconium complex [(C5H4R)(2)Zr(BH4)(THF)]BPh4, and the structure of [(C5H4Me)(2)Zr(BH4)(THF)]BPh4 was determined. In the presence of phosphine, PMe2Ph, the formation of the cationic hydride [(C5H4R)(2)ZrH(PMe2Ph)(2)]BPh4 is observed by H-1 and P-31 NMR followed by a disproportionation and a redox reaction with [BPh4](-), giving the neutral [(C5H4R)(2)ZrH(mu-H)](2) and the cationic Zr-III species [(C5H4R)(2)Zr(PMe2Ph)(2)]BPh4 characterized by EPR spectroscopy and suggesting a probable pathway in the deactivation of cationic catalyst systems.