1,3,5-hexatriene molecular orbital calculation

Molecular orbital calculations on fluorinated butadienes and hexatrienes were used to model the effects of fluorination on the properties of poly(acetylene). Like poly(acetylene), "head-to-head" poly(fluoro- acetylene), (-CH=CF-CF=CH-), is predicted to adopt a planar, all trans structure, but poly(difluoro-acetylene) favors a non-planar skewed chain conformation. "Head-to-tail" poly(fluoroacetylene), (-CH=CF-CH=CF-) is predicted to favor a nearly planar cis structure stabilized by intramolecular CF-HC hydrogen binding. Calculations on 2-fluoroethanol and on both 2-fluoroacetaldehyde enol and its alkali metal (Li, Na, K) enolates reveal moderately strong intramolecular CF—HO hydrogen bonds(1.9 and 3.2 kcal/mol, respectively) and even stronger intramolecular coordination of CF to alkali metal cations (9-12 kcal/mol). 

Why is the thermal stability of diarylethene derivatives enhanced by replacing phenyl groups with furan or thiophene groups In molecular orbitals calculation, the photochromic reaction is treated as a typical electrocyclic reaction between hexatriene and cyclohexadiene. The thermal reaction proceeds disrotatorily and the photoreaction, conrotatorily. Disrotatory cyclization of A to B requires an increase in free energy larger than 138 kJ/mol, and hence no thermal ring-closure occurs in the case of either phenyl- or furan-substituted molecules (see... 

Draw all of the 77 molecular orbitals for (3E)-l,3,5-hexatriene, order them from lowest to highest in energy, and indicate the number of electrons that would be found in each in the ground state for the molecule. After doing so, open the computer molecular model for (3E)-1,3,5-hexatriene and display the calculated molecular orbitals. How well does the appearance and sequence of the orbitals you drew (e.g., number of nodes, overall symmetry of each, etc.) compare with the orbitals in the calculated model Are the same orbitals populated with electrons in your analysis as in the calculated model ... 

Use this expression to determine a reasonable empirical estimate of the parameter )3 for the series consisting of ethene, butadiene, hexatriene, and octatetraene given that light-induced absorptions from the HOMO to the LUMO occur at 61 500,46 080,39 750, and 32 900 cm h respectively, (b) Calculate the delocalization energy of octatetraene (see Exercise 10.36). (c) In the context of this Huckel model, the % molecular orbitals are written as linear combinations of the carbon 2p orbitals. The coefficient of the jth atomic orbital in the fcth molecular orbital is given by... 

Table 7 summarizes several predictions of mid-sized aromatic molecules from the study of Matsuzawa and Dixon. The p value for a molecule with the inversion symmetry operation (benzene) is zero from symmetry arguments. Note that there are sizeable deviations among the experimental observations of p and Y values, as they are also properties difficult to measure. Agreement in Table 7 should be considered reasonably good. Matsuzawa and Dixon have also compared their calculated y values of ethylene, frans-butadiene, and trans-hexatriene with those obtained from ab initio molecular orbital methods the results from their study show that B-LYP calculations are more accurate than those at the Hartree-Fock level and are of comparable accuracy to MP2 results. 

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