| 154798-32-0

• CAS: 154798-32-0
• 化学式: C₄₅H₄₃ClIrP₃
• 分子量: 904.431
• InChiKey: OHESPNQCUYGZNQ-UHFFFAOYSA-M

计算性质

• 辛醇/水分配系数(LogP)：
  None
• 重原子数：
  None
• 可旋转键数：
  None
• 环数：
  None
• sp3杂化的碳原子比例：
  None
• 拓扑面积：
  None
• 氢给体数：
  None
• 氢受体数：
  None

反应信息

• 作为反应物：
  描述：

  thallium(I) hexafluorophosphate 、 、 乙烯-13C2 以 氘代四氢呋喃 为溶剂， 生成
  参考文献：
  名称：

  Mechanistic Study of Ir(H)2-Assisted Transformations of Ethyne: Cyclotrimerization, Cooligomerization with Ethene, and Reductive Coupling

  摘要：

  The (ethene)dihydride complex [(triphos)Ir(H)(2)(C2H4)]BPh(4) (1) is capable of promoting a variety of transformations of ethyne, including cyclotrimerization to benzene, cooligomerization with ethene to hexa-1,3,5-triene, reductive coupling to buta-1,3-diene, and hydrogenation to ethene (triphos = MeC(CH(2)PPh(2))(3)). A detailed study under various experimental conditions, the detection of several intermediates along the various reaction paths, and the use of isolated complexes in independent reactions, taken together, permit mechanistic conclusions that account for the varied products. In particular, the cyclotrimerization and cooligomerization reactions are mediated by an iridacyclopentadiene species which is trapped by either ethyne or ethene. Consumption of the hydride ligands of 1 by C2H2 or C2H4 is an ingredient for both cyclotrimerization and cooligomerization reactions but is not. necessary to accomplish the reductive dimerization of ethyne to buta-1,3-diene for which, conversely, the two hydride ligands are mandatory.

  DOI：

  10.1021/om00002a046
• 作为产物：
  描述：

  (triphos)Ir(η4-benzene)(BPh4) 、 乙炔 在 (triphenylphosphine)iminium chloride 作用下， 以 四氢呋喃 为溶剂， 以80%的产率得到
  参考文献：
  名称：

  The Mechanism of Acetylene Cyclotrimerization Catalyzed by the fac-IrP3+ Fragment: The Relationship between Fluxionality and Catalysis

  摘要：

  Reaction of [(triphos)Ir(C2H4)2](BPh4) with C2H2 at 25-degrees-C gives [(triphos)Ir(eta4-C6H6)](BPh4), 1, which was shown to have this Ir/benzene connectivity by single crystal X-ray diffraction. Crystal data (-155-degrees-C): a = 16.471(6) angstrom, b = 17.126(6) angstrom, c = 12.030(4) angstrom, alpha = 101.22(2)-degrees, beta = 93.61(2)-degrees, and gamma = 75.46(1)-degrees with Z = 2 in space group Pi. This species reacts with C2H2 in the presence of Cl- to give (triphos)IrCl(eta2-C4H4), 2, which can be converted back to 1 with C2H2 in the presence of the chloride scavenger TlPF6. Ethyne will displace C6H6 from 1 at 60-degrees-C in THF, thus completing a catalytic cyclotrimerization of C2H2 to benzene. While the phosphorus nuclei in 1 form an AM2 spin system, these undergo site exchange with activation parameters DELTAH = 10.7(3) kcal/mol and DELTAS = -9.5(6) kcal-1 mol-1. The benzene ring H-1 NMR spectra are also temperature-dependent, and the fluxionality can be accounted for by the same activation parameters appropriate to P-31 site exchange; the same physical mechanism thus accomplishes both site exchanges. The structural study indicates that eta4-C6H6, which is nonplanar, is a stronger pi-acceptor than is butadiene itself. A multistep mechanism has been studied with extended Huckel calculations. It is shown that the C-C bond formation between the first two alkynes to give the unsaturated metallacyclopentadiene is permitted when the three spectator ligands are in a fac geometry but is forbidden when they are in a mer geometry, which explains the puzzling difference of reactivity between monodentate triphosphine and tripodal complexes. It is shown that this unsaturated metallacycle is highly reactive toward an incoming ligand since it is not strongly stabilized by conjugation within the pi system. This explains why it can be isolated by trapping with a Lewis base. The addition of the third alkyne to the metallacyclopentadiene, leading to the eta4-benzene complex, can be achieved in a concerted manner and leads directly to the product. The C-C bond lengths within the eta4-benzene are shown to be due to the presence of a potent metal donor and to the nonplanarity of the benzene ring. The fluxionality of the eta4-benzene, which makes all carbons of the ring and the three phosphine ligands equivalent on the NMR time scale, is suggested to be due to an easy displacement/rotation of the IrP3+ fragment around the ring. This displacement avoids eta6-coordination (20-electron species) but passes through unsaturated eta3- and eta2-benzene coordination modes. These unsaturated species (notably the eta2 one) have the proper low-lying LUMO to coordinate an additional alkyne. This leads back to the monoalkyne complex and benzene production. Fluxionality and reactivity of the eta4-benzene ring are therefore interrelated. The efficiency of the catalysis is suggested to be due to the fact that all intermediates are reactive 16-electron species stabilized by additional donation from the conjugated pi system of the organic ligand. The presence of an enforced fac arrangement of the three spectator ligands avoids the thermodynamic trap of the trigonal bipyramidal bis(alkyne) complex.

  DOI：

  10.1021/om00017a067

文献信息

• Molecular Solid-Gas Organometallic Chemistry. Catalytic and Stoichiometric Iridium-Assisted C-C Bond-Forming Reactions Involving Ethyne and Ethene
  作者：Claudio Bianchini、Mauro Graziani、Jan Kaspar、Andrea Meli、Francesco Vizza

  DOI：10.1021/om00016a020

  日期：1994.4

  Treatment of crystals of the (eta2-ethene)dihydride complex [(triphos)Ir(H)2(C2H4)]BPh4 (1; triphos = MeC(CH2PPh2)3) with ethyne (4 atm) at 70-degrees-C for 3 h results in evolution of ethene and but-2-ene and formation of five different organometallic products, namely the eta4-benzene complex [(triphos)Ir(eta4-C6H6)]BPh4 (2), the eta4-buta-1,3-diene complex [(triphos)Ir(eta4-C4H6)]BPh4 (3), the eta4-cyclohexa-1,3-diene complex [(triphos)Ir(eta4-C6H8)]BPh4 (4), and the crotyl hydride isomers [(triphos)Ir(H) (eta3-MeC3H4)]BPh4 (5-anti and 5-syn) in a kinetic product ratio of 35:5:23:28:9. At 100-degrees-C, the solid-gas reaction produces catalytic amounts of benzene, the catalyst precursor being the eta4-benzene complex 2. Temperature-programmed reactions carried out in a flow reactor and the use of isolated complexes in independent solid-gas reactions permit mechanistic conclusions which account for the varied organic and organometallic products. The ethene ligand in 1 is an essential ingredient for both cyclotrimerization and cooligomerization reactions of ethyne, which are traversed by eta3-crotyl complexes. Conversely, the ethene ligand is a competitive inhibitor for the reductive dimerization of ethyne to buta-1,3-diene, for which the two hydride ligands are mandatory. Comparison with fluid solution-phase systems provides evidence for the control exerted by the constraining environment of the crystal lattice on the solid-gas reactions.