(κ3-C6H3-2,6-(CH2P(t)Bu2)2)Ir(CO)(CH=CHPh)[CCPh] | 928044-61-5

• 英文名称: (κ3-C6H3-2,6-(CH2P(t)Bu2)2)Ir(CO)(CH=CHPh)[CCPh]
• 英文别名: (PCP)Ir(CO)(CH=CHPh)[CCPh]
• CAS: 928044-61-5
• 化学式: C₄₁H₅₅IrOP₂
• 分子量: 818.055
• InChiKey: FKMKBZCPYLUOSP-UHFFFAOYSA-N

反应信息

• 作为反应物：
  描述：

  (κ3-C6H3-2,6-(CH2P(t)Bu2)2)Ir(CO)(CH=CHPh)[CCPh] 以 not given 为溶剂， 生成 (PCP)Ir(trans-1,4-phenyl-but-3-ene-1-yne)
  参考文献：
  名称：

  Dimerization of Alkynes Promoted by a Pincer-Ligated Iridium Complex. C−C Reductive Elimination Inhibited by Steric Crowding

  摘要：

  The pincer-ligated species (PCP)Ir (PCP = kappa(3)-C6H3-2,6-((CH2PBu2)-Bu-t)(2)) is found to promote dimerization of phenylacetylene to give the enyne complex (PCP)Ir(trans-1,4-phenyl-but-3-ene-1-yne). The mechanism of this reaction is found to proceed through three steps: (i) addition of the alkynyl C-H bond to iridium, (ii) insertion of a second phenylacetylene molecule into the resulting Ir-H bond, and (iii) vinyl-acetylide reductive elimination. Each of these steps has been investigated, by both experimental and computational (DFT) methods, to yield unexpected conclusions of general interest. (i) The product of alkynyl C-H addition, (PCP)Ir(CCPh)(H) (3), has been isolated and, in accord with experimental observations, is calculated to be 29 kcal/mol more stable than the analogous product of benzene C-H addition. (ii) Insertion of a second PhCCH molecule into the Ir-H bond of 3 proceeds rapidly, but with a 1,2-orientation. This orientation gives (PCP)Ir(CCPh)(CPhCH2) (4) which would yield the 1,3-diphenyl-enyne if it were to undergo C-C elimination; however, the insertion is reversible, which represents the first example, to our knowledge, of simple beta-H elimination from a vinyl group to give a terminal hydride. The 2,1-insertion product (PCP)Ir(CCPh)(CHCHPh) (6) forms more slowly, but unlike the 1,2 insertion product it undergoes C-C elimination to give the observed enyne. (iii) The failure of 4 to undergo C-C elimination is found to be general for (PCP)Ir(CCPh)(vinyl) complexes in which the vinyl group has an alpha-substituent. Thus, although C-C elimination relieves crowding, the reaction is inhibited by increased crowding. Density-functional theory (DFT) calculations support this surprising conclusion and offer a clear explanation. Alkynyl-vinyl bond formation in the C-C elimination transition state involves the vinyl group pi-system; this requires that the vinyl group must rotate (around the Ir-C bond) by ca. 90 degrees to achieve an appropriate orientation. This rotation is severely inhibited by steric crowding, particularly when the vinyl group bears an alpha-substituent.

  DOI：

  10.1021/ja0647194