An Air/Water-Stable Tridentate N-Heterocyclic Carbene- Palladium(II) Complex: Catalytic CH Activation of HydrocarbonsviaHydrogen/Deuterium Exchange Process in Deuterium Oxide
摘要:
Abstractmagnified imageWhile developing novel catalysts for carbon‐carbon or carbon‐heteroatom coupling (nitrogen, oxygen, or fluorine), we were able to introduce tridentate N‐heterocyclic carbene (NHC)‐amidate‐alkoxide palladium(II) complexes. In aqueous solution, these NHC‐Pd(II) complexes showed high ability for CH activation of various hydrocarbons (cyclohexane, cyclopentane, dimethyl ether, tetrahydrofuran, acetone, and toluene) under mild conditions.
The activation of C−H bonds of alkanes remains a major challenge for chemistry. In a series of deuteration experiments with D2 in contact with bis‐(diphenylphosphino) butane (dppb) stabilized ruthenium nanoparticles (liquid substrates, 60 °C, 6 bar D2) we have observed a surprisingly large reactivity of cyclopentane as compared to cyclohexane and other alkanes. DFT calculations using a ligand‐free
烷烃CH键的活化仍然是化学领域的主要挑战。在一系列的氘化实验中,D 2与双(二苯基膦基)丁烷(dppb)稳定的钌纳米颗粒(液体底物,60°C,6 bar D 2)接触,我们观察到环戊烷与环己烷相比具有惊人的大反应活性和其他烷烃。使用不含配体的Ru 13 H 17模型簇作为催化剂的DFT计算表明,作为限速反应步骤,结合的底物的氧化CH裂解。它们还表明环戊烷和环己烷的反应具有相似的结合和活化焓。
Tanner, Dennis D.; Ruo, Tomoki C-S.; Takiguchi, Hideki, Canadian Journal of Chemistry, 1981, vol. 59, p. 1368 - 1374
作者:Tanner, Dennis D.、Ruo, Tomoki C-S.、Takiguchi, Hideki、Guillaume, Andre
DOI:——
日期:——
Photolysis and radiolysis of cyclopentane in the liquid phase
作者:P. Ausloos、S. G. Lias、R. E. Rebbert
DOI:10.1021/j150616a006
日期:1981.8
Faro, Arnaldo C.; Kemball, Charles, Journal of Chemical Research, Miniprint, 1984, # 11, p. 3208 - 3244
作者:Faro, Arnaldo C.、Kemball, Charles
DOI:——
日期:——
The Infra‐Red and Raman Spectra of Cyclopentane, Cyclopentane‐<i>d</i><sub>1</sub>, and Cyclopentane‐<i>d</i><sub>10</sub>
作者:Foil A. Miller、Richard G. Inskeep
DOI:10.1063/1.1747535
日期:1950.12
The infra-red and Raman spectra of cyclopentane, cyclopentane-d1, and cyclopentane-d10 have been determined for the purpose of establishing the symmetry of cyclopentane. D5h selection rules are found to hold very well. This does not constitute a rigorous criterion for structure in this case, however, because drastic alteration of the symmetry by substituting groups such as D, OH, CH3, or Cl for a hydrogen atom does not appreciably increase the complexity of the spectra. The data have provided two strong arguments against a D5h structure. (1) An assignment could not be made which simultaneously satisfied the product rule and the expected band contours. (2) The entropy of the vapor demands a low frequency (near 140 cm−1 for the assignment in this paper) if the symmetry is D5h. This is completely incompatible with the heat capacity of the solid.
It is concluded that cyclopentane definitely does not have D5h symmetry. The actual geometry of the molecule is still not known. It is shown that a rigid structure of symmetry Cs, C2, or C1 is consistent with the available data. A decision between this and Kilpatrick, Pitzer, and Spitzer's model with a puckered ring and a pseudorotation in place of one of the genuine normal vibrations cannot be made at this time.
Analogous spectroscopic results for perfluorocyclopentane are mentioned briefly for comparison. This molecule is definitely non-planar.
The method of preparation of the deuterium compounds is given. A Pd-on-charcoal catalyst is described which promises to be useful in other hydrogen-deuterium exchange reactions.