646069-74-1Relevant academic research and scientific papers
Rational design of highly active "hybrid" phosphine-phosphinite pincer iridium catalysts for alkane metathesis
Nawara-Hultzsch, Agnieszka J.,Hackenberg, Jason D.,Punji, Benudhar,Supplee, Carolyn,Emge, Thomas J.,Bailey, Brad C.,Schrock, Richard R.,Brookhart, Maurice,Goldman, Alan S.
, p. 2505 - 2514 (2013/11/19)
Both the bisphosphine and bisphosphinite pincer complexes ( tBu4PCP)IrH2 and (tBu4POCOP)IrH2 can cocatalyze alkane metathesis in tandem with olefin metathesis catalysts, but the two complexes have different resting states during catalysis, suggesting that different steps are turnover-limiting in each case. This led to the hypothesis that a complex with intermediate properties would be catalytically more active than either of these two species. Accordingly, "hybrid" phosphine-phosphinite pincer ligands (PCOP) and the corresponding iridium complexes were synthesized (3c-e). In tandem with olefin-metathesis catalyst MoF12, (tBu4PCOP)IrH2 displays significantly higher activity for the metathesis of n-hexane than does (tBu4PCP)IrH 2 or (tBu4POCOP)IrH2. (tBu2PCOP iPr2)IrH4 (3d) is even more active (>30-fold more active than (tBu4POCOP)IrH2) and affords nearly 4.6 M alkane products after 8 h at 125 C.
Novel unsymmetrical PCP′ pincer ligands and their palladium(II) complexes
Eberhard, Michael R.,Matsukawa, Shiro,Yamamoto, Yohsuke,Jensen, Craig M.
, p. 185 - 189 (2007/10/03)
Synthetic routes towards novel PCP′ pincer ligands were devised. Ligand 1-(Pr2iPOCH2) -3-(Bu2tPCH2) (C6H4) is prepared in a three step synthesis from 1,3-benzenedimethanol and 1-(Pr2iPO)-3- (Bu2tPCH2)(C6H4) is accessible in three steps from 3-hydroxybenzylalcohol. Both their palladium(II) complexes are prepared in good yields but are distinctly different since [PdCl{(C6H3) (OPPr2i)-2-(CH2PBu2 t)-6}] possesses two five-membered palladacycles, whereas [PdCl{(C6H3)(CH2PBu2 t)-2-(CH2OPPr2i)-6}] is unusual for a pincer complex in that it contains both five- and six-membered palladacycles. Both compounds also represent the first examples of pincer complexes where one donor is a phosphinite and the other is a phosphine. The X-ray structures of these complexes were solved and are discussed. The data reveal that an increase in the metallacycle ring-size leads to changes in bond lengths, but more importantly to significant increases in the bond angles.
