934754-27-5Relevant academic research and scientific papers
A chromium-diphosphine system for catalytic ethylene trimerization: Synthetic and structural studies of chromium complexes with a nitrogen-bridged diphosphine ligand with ortho-methoxyaryl substituents
Agapie, Theodor,Day, Michael W.,Henling, Lawrence M.,Labinger, Jay A.,Bercaw, John E.
, p. 2733 - 2742 (2006)
To gain molecular-level insight into the important features of a chromium-diphosphine catalytic system for ethylene trimerization, the coordination chemistry of chromium with PNP ligands (PNP OMe = (o-MeOC6H4)2PN(CH 3)P(o-MeOC6H4)2, P t-BuNi-amylPOMe = (2-MeO-4-t-BuC 6H3)2PN(i-amyl)P(2-MeO-4-t-BuC 6H3)2) has been explored. Chromium(0) carbonyl complexes have been synthesized by CO displacement with diphosphine. Oxidation of Cr(CO)4{κ2-(P,P)-(PNPOMe)} with I 2, Br2, and PhICl2 generates the corresponding chromium(III) halide complexes. Chromium(III) complexes CrCl 3{(κ3-(P,P,O)-(PNPOMe)}, CrCl 3{κ3-(P,P,O)-(Pt-BuN i-amylPOMe)}, and CrCl2(CH3) {κ3-(P,P,O)-(PNPOMe)} can be synthesized by metalation with CrCl3(THF)3 or CrCl2(CH 3)(THF)3. Reaction of CrCl3{κ 3-(P,P,O)-(PNPOMe)} with o,o′-biphenyldiyl diGrignard affords CrBr(o,o′-biphenyldiyl){κ3-(P,P,O)- (PNPOMe)}. Single-crystal X-ray diffraction studies show that the Cr-O and Cr-P distances can vary significantly as a function of metal oxidation state and the other ligands bound to chromium. Variable-temperature 2H NMR spectroscopy studies of chromium(III) complexes supported by PNP ligands indicate fluxional behavior with the ether groups interchanging at higher temperatures. Low-temperature 2H NMR spectra are consistent with solution structures similar to the ones determined in the solid state.
