Free jet rotational spectrum and Ar inversion in the dimethyl ether–argon complex

Ottaviani, Paolo; Maris, Assimo; Camináti, Walther; Tatamitani, Yoshio; Suzuki, Yasufumi; Ogata, Teruhiko; Alonso, José L.

doi:10.1016/s0009-2614(02)00958-2

Cited by 36 publications

(41 citation statements)

References 22 publications

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“…The V 2 barrier, which was found for the tunneling motion of the Ar atom above and below the plane of DMS with the flexible model for reproducing the experimental splittings, was consistently lower than the MP2/6-311G** value; this suggests that, for this kind of systems, these calculations give only qualitative information on weak interactions. A similar overestimation of the potential energy surface that describes the Ar tunneling motion was observed in the related complex dimethyl etherAr (DME-Ar), [22] the only molecular complex with a heavy-atom frame similar to that of DMS-Ar which has been investigated by rotational spectroscopy. The main changes on going from DME-Ar to DMS-Ar (i.e., replacing an O atom with an SiH 2 group) are: 1) the equilibrium position of Ar in the global minimum moves considerably towards the two methyl groups; 2) the Ar tunneling barrier decreases from 58 to 12 cm À1 ;…”

Section: Discussionmentioning

confidence: 53%

Molecular Complexes of Organometallic Molecules with Noble Gases: The Rotational Spectrum of Dimethylsilane–Argon

et al. 2004

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The rotational spectrum of the molecular complex dimethylsilane-argon was investigated by free-jet absorption millimeter-wave and molecular-beam Fourier transform spectroscopy. The absolute energy minimum corresponds to a conformation in which the argon atom lies in the plane of symmetry of dimethylsilane, perpendicular to the C-Si-C plane. The distance of Ar atom is tilted 14 degrees away from the Si atom. The zero-point dissociation energy was estimated from the centrifugal distortion constant D(J) to be 2.2 kJ mol(-1). Small splitting, due to tunneling of the Ar atom and internal rotation of the two methyl groups, was observed, measured, and used to determine the potential energy surface for these motions.

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Section: Discussionmentioning

confidence: 53%

Molecular Complexes of Organometallic Molecules with Noble Gases: The Rotational Spectrum of Dimethylsilane–Argon

et al. 2004

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“…However, they give a first estimate of the position of the noble gas atom. Both a and 180 À a values are consistent with the experimental data, but, as for DME ± Ar [5] and DME ± Ne, [6] the former value, for which the noble gas atom is tilted towards the oxygen atom, was chosen. A method for estimating r e is described below.…”

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confidence: 84%

“…The first estimates of the rotational constants of the DME ± Xe were obtained by placing the xenon atom at a distance of 3.82 ä from the center of mass (CM) of DME, lying along the c axis of DME, but shifted by about 158 towards the oxygen atom, in a geometrical arrangement similar to that found for DME ± Ar [5] and DME ± Kr.…”

Section: Introductionmentioning

confidence: 99%

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Adducts of Xenon with Organic Molecules: Rotational Spectrum of Dimethyl Ether–Xe

et al. 2003

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KEYWORDS:gas-phase reactions ¥ noble gases ¥ rotational spectroscopy ¥ van der Waals adducts ¥ xenon Considerable interest has been devoted during the last two decades to the investigation of the rather unusual ™chemical compounds∫ formed by the combination of a noble gas atom with an organic molecule.[1] Various spectroscopic methods have been used to observe these adducts in the plume following a supersonic expansion.[2] Many van der Waals adducts between a noble gas atom and a cyclic organic molecule have been investigated by rotationally resolved spectroscopy, but only a very few involve a Xe atom: benzene ± Xe [3] and oxirane ± Xe [4] . The lack of experimental data on this kind of Xe complexes is probably due to the mass of Xe, which makes the rotational constants of its van der Waals complexes smaller than those of complexes of the lighter noble gases, and the large number of isotopes, with a maximum of natural abundance (27 %) for 132 Xe. Both factors considerably reduce the intensities of the rotational lines.Due to the higher polarizability of Xe relative to lighter noble gases, a larger dispersion ± energy interaction is expected for complexes with Xe. Here, we compare the stability and the dynamics of the noble gas atom in dimethyl ether ± xenon (DME ± Xe) to those of the related adduct oxirane ± Xe [4] and of the complexes of DME with Ne, Ar, and Kr, whose jet-cooled rotational spectra have been observed.[5±7] Figure 1 shows DME ± Xe and the van der Waals structural parameters.The first estimates of the rotational constants of the DME ± Xe were obtained by placing the xenon atom at a distance of 3.82 ä from the center of mass (CM) of DME, lying along the c axis of DME, but shifted by about 158 towards the oxygen atom, in a geometrical arrangement similar to that found for DME ± Ar [5] and DME ± Kr.[7] The r 0 geometry of DME [8] was assumed to Figure 1. Schematic diagram of DME ± Xe with van der Waals structural parameters.remain unaltered in the complex. On going from the molecule to the adduct the directions of the principal axes of inertia with respect to the C-O-C skeleton change, so that the m b -type spectrum of DME changes to a predominantly m c -type spectrum in the adduct (Figure 2). Figure 2. Switching of principal axes on going from DME to DME ± Xe.The rotational spectra of the two most abundant isotopic species, with 132 Xe and 129 Xe (ca. 27 and 26 % natural abundance, respectively), were investigated. Several high-J high-K a m c -R-type lines, doubly overlapping due to the near-prolate behaviour of K a , were easily assigned; later, the weaker lines with lower K a values, resolved into asymmetry doublets, were measured. The experimental frequencies (Table 1) were fitted with the Watson quartic Hamiltonian.[9] Since DME ± Xe is a near-prolate top, the S reduction and the I r representation were chosen. Three quartic centrifugal distortion parameters D J , D JK and D K were determined from the fit. The spectroscopic constants obtained are listed for both isotopomers in Table 2 together w...

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“…The role of H-bonds has been commonly related to a great variety of physicochemical phenomena [7][8][9][10][11]. Recently, reactions and equilibrium processes driven by H-bonding [12][13][14] have attracted much attention.…”

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Theoretical investigation of hydrogen bonding in lactonitrile–water complexes

Rivelino

Canuto

2005

Int J of Quantum Chemistry

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ABSTRACT:Møller-Plesset perturbation and density functional theories were applied to study the relative strength of the H-bonds formed in different sites (OH, CN, and CH) of lactonitrile with water. Three lactonitrile-water complexes (termed I, II, and III) were located. Then structures, binding energies, and changes in their vibrational frequencies were calculated using the MP2 method and the B3PW91 functional with the 6-311ϩϩG(2df,2p) basis set. The binding energies were corrected for the basis set superposition errors and zero-point vibration energies. At the MP2 level the corrected binding energy of the most strongly bonded Complex I was calculated to be 6.5 kcal/ mol, whereas it is only 2.9 kcal/mol for the Complex II. The CH . . . O hydrogen-bonded Complex III was found to have a very small binding energy between 1.5 and 2 kcal/ mol.

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Free jet rotational spectrum and Ar inversion in the dimethyl ether–argon complex

Cited by 36 publications

References 22 publications

Molecular Complexes of Organometallic Molecules with Noble Gases: The Rotational Spectrum of Dimethylsilane–Argon

Molecular Complexes of Organometallic Molecules with Noble Gases: The Rotational Spectrum of Dimethylsilane–Argon

Adducts of Xenon with Organic Molecules: Rotational Spectrum of Dimethyl Ether–Xe

Theoretical investigation of hydrogen bonding in lactonitrile–water complexes

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