Dimerization benzene

Fig. 36. Spatial fit between host and guest in 47 benzene (1 1) (see Ref. 64) (a) Electron density in the mean plane of a benzene revealing the encasing hexagonal environment aroung the guest and (b) and (c) van der Waals surfaces of the dimeric benzene units as seen in Fig. 27 (indicated dimensions were calculated by the aid of the CHEM X program system, see Ref. 139). The lack of extensive-enough overlapping to yield in pi-pi interactions is visible from this drawing...

Sherrill, C. D. Takatani, T. Hohenstein, E. G. An assessment of theoretical methods for nonbonded interactions comparison to complete basis set limit coupled-clusta-potential enragy curves for the benzene dimer, the methane dimer, benzene—methane, and benzene—H2S, / Phys. Chem. A 2009,113,10146-10159. 

Jahn-Teller distorted state. ENDOR results of dimeric benzene cation formed after warming in CFCI3 and present in CF3CCI3 at all temperatures indicate that the dimer had a sandwich structure in both matrices. An EPR study of the benzene radical cation in argon matrix generated by fast electron irradiation at 16 K showed favorable stabilization of big state rather than b2g state, in contrast to previous results found in Freon matrices [180]. 

It seems reasonable to assume that the dimeric benzene ion has a sandwich conformation. A similar structure has been invoked to explain excimer spectra from neutral benzene molecules in solution where stable dimers are observed (27). Also Howarth and Fraenkel (II) have suggested that the two hydrocarbon moieties of the dimeric ion of naphthalene lie in parallel planes. Ishitani and Nagakura (12) have suggested a sandwich structure for paracyclophane anions but they also consider the possibility of a diphenyl type of structure. 

FIGURE 10.4 Binding in water dimer, benzene dimer, and water-benzene dimer by EFP. All values are in kcal/mol. 

EFP interaction energies in the water dimer, benzene dimers, and water-benzene dimers are compared in Fig. 5.1 [39]. Interaction in the water dimer is dominated by the Coulomb term (—8.6 Real/ mol), whereas the polarization and dispersion components are almost 10 times weaker. Contrarily, dispersion forces (—4.9 Real/ mol) determine binding in the parallel-displaced benzene dimer. Interestingly, the two structures of the benzene-water dimer and the T-shaped benzene dimer exhibit significant contributions from... 

CfteH32Br202 1.5 CsHg, 3-Bromo-2,4,6-triphenylphenoxyl dimer benzene solvate, 33B, 66... 

CafiHi2CS2N12f Caesium tetracyanoguinodimethanide, 29, 650 31B, 43 C38H34OS, Obtusaguinone dimer benzene solvate, 42B, 9l... 

Interaction energy components for the water dimer, benzene dimer, and the CI2--OH2 complex. The water dimer is in its equilibrium geometry, the benzene dimer is in the parallel stacked geometry with center-of-mass separation 3.7A, and the Cl2"-OH2 complex Is In a symmetrical complex with all atoms in a plane and Cl-Cl 0 collinear with r(CI-"0)= 2.755 A. All energies are reported InkJmor ... 

The R12 methods have been applied to larger systems. For example, the structure and energetics of crystalline tri-hydrated tricyclic oithoamide, [10]annulene, small water clusters, " intermolecular interactions (He dimer, HF dimer, benzene... Ne), " and ferrocene have been investigated. As a representative example, the computation of a quantitatively accurate six-dimensional PES for the HF dimer is discussed in Section 6.2. 

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