On the ethene/HCl Van der Waals complexes observed in liquefied argon and liquefied nitrogen

Abstract

Articles you may be interested inCalculation of the structure, potential energy surface, vibrational dynamics, and electric dipole properties for the Xe:HI van der Waals complexThe effect of weak interactions on the ring puckering potential in the coumaran-argon van der Waals complex: Experimental and ab initio analysis of the intermolecular and low-frequency intramolecular vibrationsThe mid-infrared (4000-400 cm Ϫ1 ) and far-infrared (300-10 cm Ϫ1 ) spectra of C 2 H 4 /HCl mixtures, dissolved in liquefied argon ͑93-125 K͒ and in liquefied nitrogen ͑80-118 K͒ are discussed. In all spectra, experimental evidence was found for the existence of 1:1 and 1:2 Van der Waals complexes. Using spectra recorded at different temperatures, the complexation enthalpy ⌬H°f or the 1:1 complex was determined to be Ϫ8.7(2) kJ mol Ϫ1 in liquid argon and Ϫ6.4(4) kJ mol Ϫ1 in liquid nitrogen, while for the 1:2 complex a ⌬H°of Ϫ18.3(6) kJ mol Ϫ1 was found. For all species studied, the vibrational frequencies were obtained from ab initio calculations at the MP2/6Ϫ311ϩG** level. Using the SCRF/SCIPCM scheme to correct for the solvent influences, and using statistical thermodynamics to account for the zero-point vibrational and thermal contributions, approximate values for the dissociation energy were calculated from the complexation enthalpies. The resulting values, Ϫ12.7(5) kJ mol Ϫ1 for the 1:1 complex and Ϫ26.9(2) kJ mol Ϫ1 for the 1:2 complex are compared with the ab initio values. The transition dipole moment of the 2 ethene mode induced in the 1:1 complex is determined to be 0.13 D Å Ϫ1 . A multipole analysis shows that the main contribution is due to the quadrupole moment of the HCl moiety, closely followed by that due to the dipole moment, with much smaller contributions due to higher multipoles. In the 1:1 complex, the HCl stretching intensity is enhanced by a factor of 7.7 in comparison with the monomer. This increase is interpreted in the equilibrium charge-charge flux model using ab initio atomic polar tensors.

Photocatalytic degradation of ethylene: An FTIR in situ study under atmospheric conditions

“…Apart from the bands present in the ethylene monomer, some new bands of interest occurred particularly in the region from 1900 to 1300 cm −1 . Based on earlier studies on Pt/TiO 2 , the bands at 1690 and 1377 cm −1 can be assigned to formate species associated with TiO 2 [18,19] but, more importantly, the band at 1618 cm −1 can be assigned to the C C stretch of ethylene, while the band at 1343 cm −1 can be assigned to CH 2 vibrations of ethylene [20]. These bands are normally not active in the infrared vibration spectrum, but they become visible when a change in the dipole moment of the molecule is induced.…”

“…by a van der Waals interaction between a permanent dipole and its induced dipole. The permanent dipole is the partially positive charged hydrogen atom on the surface of the catalyst, while the induced dipole is caused by this permanent dipole and the partially negative charge of the -system from ethylene [20].…”

“…These bands are assigned to chemisorbed water on the surface [12] and the stretching vibration of ethylene [20]. On the other hand, [21][22][23]) and 1360 cm −1 ( s (COO) [21][22][23]) should be found [21].…”

On the HCl and DCl complexes of methylenecyclopropane in liquid argon

“…with ethene, has been intensively studied by a variety of methods, including matrix-isolation IR spectroscopy,1,2 FT-microwave spectroscopy3,4 and cryospectroscopy. 5,6 The stability of the 1 : 1 bonded complex in liquid argon (LAr), expressed as a complexation enthalpy *H¡, was determined to be [8.7(3) kJ mol~1. 6 The CÈC bonds in cyclopropane are highly strained, and therefore, are regarded as pseudo-p bonds.…”

A Cryospectroscopic Study of the van der Waals Complexes between Vinyl Fluoride and Boron Trifluoride: Evidence for the Existence of σ and π Complexes

“…The solvation energies were calculated at the RHF/6-31+G(d) level and were found to be 2.43, 3.88, and 4.25 kJ mol -1 for C 2 H 3 F, BF 3 , and σ-C 2 H 3 F‚BF 3 , respectively. Equating, as before, 3,13 these energies to solvent enthalpies, it follows that in liquid argon the σ complex is less stable by 2.06 kJ mol -1 than in the gas phase. Using this value, and using the experimental ∆H°L Ar of -11.2(3) kJ mol -1 , ∆H°g as is calculated to be -13.3-(3) kJ mol -1 .…”