Benzene, ground state configuration

For the d9 configuration, with a 2II(a2 it3 S4) ground state, only one sandwich complex, Co(HMBz)2, is known (108). This was shown to have a moment of 1.86 0.08 B.M. at 83 and 295 K, and a permanent dipole moment of 1.78 D in benzene solution. Although there are no indications of a static distortion to be found from X-ray diffraction studies (7), this latter observation appears to afford clear cut evidence of an effective symmetry lower than Cxv, and the magnetic data were shown (101) to imply A 1100 cm-1 in order to reproduce the essentially temperature independent moment observed. However, two cautions should be observed in assessing this evidence. Firstly the predicted temperature... 

Apart from pure benzene and pure polar solvents, either acetonitrile or methanol, we have considered xp = 0.2 and xp = 0.7 molar fractions of the polar solvent. Systems ranging from 256 (pure benzene) to 512 (pure polar solvents) molecules were used. From well equilibrated (1 ns) simulations with the coumarin in the ground state So, one to two hundred equally distant configurations were selected. In these configurations the coumarin state was switched to the Si state and the solvent was let to relax in a series of 10 ps long NVE simulations. The solvent response was monitored using the normalized time-dependent stokes-shift function ... 

Fig. 13 Hiickel pi MO s and ground-state pi-electron configuration of benzene.

Write down the electronic configurations for the ground states of the molecules water, carbon dioxide, formaldehyde, ethene, benzene, and the nitrogen dioxide radical. The occupied MO s shall be given using the full point group symmetry of the molecule. 

The ground-state complex between benzene and maleic anhydride was found to have the exo configuration. Bryce-Smith and Hems [44] have measured nuclear magnetic resonance chemical shifts of the ethylenic protons of maleic an-... 

The electronic configuration in Figure 16-7 indicates that cyclobutadiene should be unstable. Its highest-lying electrons are in nonbonding orbitals (ir2 and ir3) and are therefore very reactive. According to Hund s rule, the compound exists as a diradical (two unpaired electrons) in its ground state. Such a diradical is expected to be extremely reactive. Thus, molecular orbital theory successfully predicts the dramatic stability difference between benzene and cyclobutadiene. 

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