Benzene interactions

For molecular species, the interaction is to be interpreted as some kind of average over all the possible geometries. A typical plot for the van der Waals benzene-benzene interaction is shown in Figure 1.12. 

Lowering the temperature has a similar effect on the deuterium spectra as does increased loadings. In Figure 3, spectra for benzene-d6/(Na)X at 0.7 molecules/supercage over the temperature range 298 to 133 K are shown. It is observed that both benzene species are detected simultaneously between 228 and 188 K. Below this temperature the oriented benzene species becomes the predominant form. A similar situation occurs for polycrystalline benzene-dg in which two quadrupole patterns, one static and the other motionally narrowed due to C rotation, are observed to coexist at temperatures between 110 and 130 K (7). This behavior has been attributed to sample imperfections (8) which give rise to a narrow distribution in correlation times for reorientation about the hexad axis. For benzene in (Na)X and (Cs,Na)X such imperfections may result from the ion/benzene interaction, and a nonuniform distribution of benzene molecules and ions within the zeolite. These factors may also be responsible for producing the individual species. However, from the NMR spectra it is not possible to... 

In the two previous sections, evidence has been presented concerning the chemisorbed states formed when benzene interacts with metal surfaces. It is not the intention in this Section to discuss benzene hydrogenation in detail, but rather to enquire whether studies of this hydrogen-addition reaction provide information about the chemisorbed state of benzene. 

Figure 2.45. Adsorption structures of benzene on Cu(110) optimized using DFT. (Left) The quinoid structure with carbon backbone distorted in an inverted boat conformation and (Right) undistorted benzene interacting through polarization of the -system and with minor upwards bending of the hydrogens. From Ref. [84].

Benzene-benzene interactions were modeled with a Buckingham potential that was shown to yield reasonable predictions of the properties of liquid and solid benzene. Benzene-zeolite interactions were modeled by a short-range Lennard-Jones term and a long-range electrostatic term. In total, 16 benzene molecules were simulated in a unit cell of zeolite Y, corresponding to a concentration of 2 molecules per supercage. Calculations ran for 24 ps (after an initial 24-ps equilibration time) for diffusion at 300 K. 

The vibrational spectrum of benzene around 1000 cnf has also been measured. IQ. Benzene was physisorbed on a cooled copper substrate in the vacuum chamber. Figure 19 shows the transmission for several thicknesses of benzene and a prism separation of 3 cm. The thickness was determined from the measured transmission in transparent regions using Eg. (7). The solid curves were calculated from Eqs. (5) and (6) using optical constants for benzene obtained from an ordinary transmission experiment.il The benzene film was assumed to be isotropic. Of the two absorption lines seen, one belongs to an in-plane vibrational mode, and one to an out-of-plane vibration. Since the electric field of the SEW is primarily perpendicular to the surface, the benzene molecules are clearly not all parallel or all perpendicular to the copper surface. Also it should be noted that the frequencies are the same (within the experimental resolution) as those of solid benzene22 and of nearly the same width. These features indicate that the benzene interacts only weakly with the copper surface, as would be expected for physisorbed molecules. 

The first application of hierarchical SA for parameter estimation included refinement of the pre-exponentials in a surface kinetics mechanism of CO oxidation on Pt (a lattice KMC model with parameters) (Raimondeau et al., 2003). A second example entailed parameter estimation of a dual site 3D lattice KMC model for the benzene/faujasite zeolite system where benzene-benzene interactions, equilibrium constants for adsorption/desorption of benzene on different types of sites, and diffusion parameters of benzene (a total of 15 parameters) were determined (Snyder and Vlachos, 2004). While this approach appears promising, the development of accurate but inexpensive surfaces (reduced models) deserves further attention to fully understand its success and limitation. 

In Figure 2, the calculated dependence of the 29Si chemical shift of the (Me3Si)3Si(CgH6)+ complex on the Si-C(benzene) interaction distance is shown. There is a linear relationship between shift value and SiC distance that gives an increase of 62 ppm for an elongation of the Si-C distance by 0.1 A. In most cases... 

A column operated at 80°C contains 2.64 g of C24H5Q as stationary phase column inlet pressure is 907 mm Hg and outlet pressure 726 mm. Observed retention volume of benzene is 285.0 ml, column dead space is 10.6 ml, and vapor pressure of pure benzene at 80°C is 760 mm. Calculate the activity coefficient for benzene, with and without the correction for the second virial coefficient Bn. Assume a value of — 1500cm /mole for for benzene-benzene interaction, neglecting solute-gas and gas-gas interactions. 

Chemistry Center, Lund), and Robert E. Carter (Chemistry Center, Lund) Benzene-Benzene Interactions Molecular Mechanics Calculations. ... 

Fig. 7.21 Model structure of benzene interacting with a single nickel atom located below the centre of the benzene ring. The two extra internal coordinates, in addition to those of benzene, are the C-Ni bond and the HCNi angle.

Perfluoroalkylation of arenes makes the aromatic ring electron deficient and thus it interacts with electron-rich arenes and Lewis bases. Figure 1.9 shows the TT-electron distribution on the hexafluorobenzene and benzene ring. Most of the TT-electrons in hexafluorobenzene are withdrawn from the aromatic ring by fluorine atoms to make the aromatic ring highly electron deficient, while the —-electrons in benzene are localized inside the ring. Thus both the benzenes interact attractively in a face-to-face manner [1]. 

Cluster-benzene interactions have also been proposed to be of importance in solutions of Bearing the configuration of the HOMO of Bis in... 

In this example application, the predictions of EFP and accurate ah initio methods are compared with experimental values for the water-benzene dimer, with a focus on the question, what is the nature of the water-benzene interaction ... 

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