379269-41-7Relevant academic research and scientific papers
Synthesis of Alkylidene-Bridged Cp/Phosphido Group 4 Metal Complexes-Precursors of the (CpCPR)M-Constrained-Geometry Catalyst Family
Bredeau, Stephane,Altenhoff, Gereon,Kunz, Klaus,Doering, Steve,Grimme, Stefan,Kehr, Gerald,Erker, Gerhard
, p. 1836 - 1844 (2008/10/09)
Phosphide [PHR1Li (R1 = cyclohexyl, phenyl) addition to the fulvenes (C5H4)CMe2 (1) and (C 5H4)CHCMe3 (2) yields the corresponding phosphinoalkyl-substituted cyclopentadienides. Subsequent deprotonation at phosphorus with LDA followed by transmetalation of the resulting [(C 5H4)CR2R3PR1]Li 2 dianion equivalents to Cl2Ti(NMe2) 2 or Cl2Zr(NEt2)2(THF)2 yields the corresponding [ CpCPR1 MX2] constrained-geometry systems (eight examples, 11-18). These systems contain a chiral phosphorus center that is characterized by a low inversion barrier (ΔGinv? ranging from ca. 7.5 to 10.0 kcal mol-1). The structural and some spectroscopic features of the (CpCPR)Ti and Zr complexes were investigated by DFT calculations. Treatment with a large excess of methylalumoxane gave ethene/1-octene copolymerization catalysts. The [(C5H4)CMe2PR 1]ZrX2 systems gave the most active catalysts in this series.
