Theoretical Study On Vibrationally High-resolved Electronic Spectra Of Some Simple Complexes And Their Anions

Based on density functional theory and its time-dependent extension, the structures and frequencies of the anions and their corresponding neutrals of benzoquinone, dehydrobenzoquinone and the fourth group dichloride compounds have been calculated. In this paper, we focused on the simulation of the well-resolved electronic spectra of these molecules. Moreover, the calculated results were analyzed and discussed.1. Comprehensive study on absorption spectra of MCl2 (M=C, Si, Ge, Sn, Pb) and photoelectron spectra of MCl2-.In Franck-Condon approximation, the vibrational-resolved electronic spectra (absorption and photoelectron) of the group IVA dichlorides have been investigated systematically. Results demonstrate that the band-shapes of these simulated spectra are basically in accordance with those of the corresponding experimental or theoretical ones. The symmetric bend mode is the most active one in absorption spectrum while the most active mode in the progression of photoelectron is the symmetric stretching one. Except for the PbCl2 molecule, the Duschinsky and anharmonic effects show very mild influence on these absorption spectra. As for PbCl2, the mixing normal modes effect has on medium influence on the spectrum. The red shift of the calculated position and the much weaker absorption intensity of spectrum indicated that the anharmonic effect is significant. This is a meaningful work for predicting the above-mentioned spectra and studying the influence of Duschinsky as well as the anharmonic effect on absorption spectra of new dichloride of this group.2. Theoretical study the photoelectron spectroscopy of benzoquinide and Dehydrobenzoquinone AnionsThe geometrical structures of dehydrobenzoquinone and benzoquinone and their anion were calculated at the M06-2X/aug-cc-pVDZ level. Based on the optimized ground state structures, the frequencies of 24 normal modes of dehydrobenzoquinone (or it anion) and 27 normal modes of benzoquinone (or it anion) at different electronic states were calculated at the same calculation level. We have simulated the photoelectron spectra of dehydrobenzoquinone and benzoquinone. The simulated photoelectron spectrum of dehydrobenzoquinone at lower energy is in good agreement with the experimental or theoretical ones. However, the assignments of this spectrum differ greatly with the experimental ones. The assignments of photoelectron spectrum of benzoquinone anion are consistent with the previous work. Here, the photoelectron spectrum of benzoquinone anion arises not only from C1 symmetry in the anion to C1 symmetry in the neutral but also from C1 symmetry in the anion to Cs symmetry in the neutral. Besides, the calculated electron affinity (1.859ev) of dehydrobenzoquinone at MP4SDQ/aug-cc-pVDZ level is in good agreement with the experimental ones (1.859±0.005ev). The calculated electron affinity (2.129ev) of benzoquinone radical at M06-2X/aug-cc-pVDZ theoretical level is consistent with the experimental upper limit value (2.18ev). Finally, by analyzing the results of molecular orbital calculated by restricted open—shell method, we found that the electron detaches from σ orbitals of dehydrobenzoquinone anion, thus producing the triplet elelctronic state, and this result is consistent with experimental asymmetry parameter of this bond in higher energy region. Thus, we simulated this progression and assigned it. While, the 0-0 energy doesn’t agree with experimental ones, we can’t compare it with the low resolution experimental spectrum. This spectrum may be helpful for the further study of dehydrobenzoquinone...