Vibrational spectra of cis and trans but-2-enes: assignments, isolated CH stretching frequencies and CH bond lengths

Vibrational overtone spectra and interactions of C2H4 and H2CCHCH3 in liquid Kr

“…Table 5 summarizes the calculated values for each of the non-equivalent C-H oscillators present in gas phase propene using the B3LYP method and two basis sets. The results are compared to gas phase experimental frequencies [48]. There is very good agreement with the scaled frequencies.…”

“…The results are given on Table 5. A comparison with the gas phase isolated frequencies reported by McKean et al [48] indicates that the frequency shift should be larger than the prediction ($1 cm À1 ) of the SCRF models. Table 3 Observed frequencies and bandwidths (Dv 1/2 ) in the C-H overtone spectrum of propene dissolved in liquid krypton at 120 K and gas phase at room temperature.…”

Mechanism of Olefin Hydrogenation Catalysis Driven by Palladium-Dissolved Hydrogen

“…Adsorption of butene on clean, H surf -covered, and additionally H abs -loaded Pd(110) at 115 K produces a small CC vibration peak in the HREEL spectra (Figure 2) at 205 meV, which is similar to cis-2-butene in the gas, liquid, or solid (206− 207 meV) phase. 38 This HREELS peak disappears after flashannealing to 140 K (Supporting Information, S-2) and thus correlates with the butene TPD feature at 135 K. TPD spectra resulting from coadsorption of C 4 H 8 at 115 K on Pd(110) saturated with surface deuterium instead of hydrogen (Supporting Information, S-4) indicate that the butene desorbing in the 135 K feature contains very little D. Due to its gas-phase like CC vibration frequency, suggestive of a very weak C 4 H 8 −Pd interaction, and because of the almost complete lack of H-D exchange with the Pd surface, we tentatively assign the butene adsorption state corresponding to the 135 K TPD feature as a molecule in the second C 4 H 8 adsorbate layer. Since this species is eliminated from the surface well before the onset of the butane formation at 160 K (Figure 4), such a weakly adsorbed second layer butene species is evidently not important for the catalytic hydrogenation reaction.…”

Understanding Ligand‐Directed Heterogeneous Catalysis: When the Dynamically Changing Nature of the Ligand Layer Controls the Hydrogenation Selectivity

“…This At 160 K, the further hydrogenation step occurs giving rise to (i) disappearance of the peaks at 1648 (n(C=C)) and 1419 (d(CH 2 )) cm À1 and (ii) appearance of a new peak at 1454 cm À1 corresponding to the CH 3 deformation vibration (d(CH 3 )). [11] The combination of these observations suggest that the C=C bond becomes hydrogenated in this temperature range and a new terminal -CH 3 group appears.…”