Abstract:
Astana: Gumilev Eurasian National University, 2008.
ABSTRACT: Applying ab initio method the structures and UV-vis spectra of silicon hexacoordinated compound [Si(phen)2(OMe)2]I2 and it’s nitrate [Si(phen)2(OMe)2](NO3)2 were calculated. On the ground of comparison of theoretical and experimental data (1H NMR and electronic absorption spectra) it was shown that the theoretical method B3LYP/LanL2DZ we have used describes bis(1,10-phenanthroline) silicon complexes reasonably well. On the basis of TDDFT calculations at B3LYP/LanL2DZ level it is predicted that [Si(phen)2(OMe)2]I2 compound has charge transfer band in UV-vis spectrum at 557 nm which is associated with electron transfer from I to phen ligand while [Si(phen)2(OMe)2](NO3)2 doesn’t have one. The absence of this band in the observed spectrum of the [Si(phen)2(OMe)2]I2 complex methanol solution (10 5 M) is explained by the dissociation of the complex into ions [Si(phen)2(OMe)2]2 and 2I . We assume that this charge transfer band corresponds to peak at 400 nm in UV-vis spectrum of [Si(phen)2(OMe)2]I2 thin film. The missing of such bands in UV-vis spectrum of nitrate [Si(phen)2(OMe)2](NO3)2 film is explained by n 3 p* nature of these transitions. Significant error in prediction of charge transfer band energy is due to failure of TDDFT method to yield underestimated charge transfer electronic energies.
Description:
Astana: Gumilev Eurasian National University, 2008.
ABSTRACT: Applying ab initio method the structures and UV-vis spectra of silicon hexacoordinated compound [Si(phen)2(OMe)2]I2 and it’s nitrate [Si(phen)2(OMe)2](NO3)2 were calculated. On the ground of comparison of theoretical and experimental data (1H NMR and electronic absorption spectra) it was shown that the theoretical method B3LYP/LanL2DZ we have used describes bis(1,10-phenanthroline) silicon complexes reasonably well. On the basis of TDDFT calculations at B3LYP/LanL2DZ level it is predicted that [Si(phen)2(OMe)2]I2 compound has charge transfer band in UV-vis spectrum at 557 nm which is associated with electron transfer from I to phen ligand while [Si(phen)2(OMe)2](NO3)2 doesn’t have one. The absence of this band in the observed spectrum of the [Si(phen)2(OMe)2]I2 complex methanol solution (10 5 M) is explained by the dissociation of the complex into ions [Si(phen)2(OMe)2]2 and 2I . We assume that this charge transfer band corresponds to peak at 400 nm in UV-vis spectrum of [Si(phen)2(OMe)2]I2 thin film. The missing of such bands in UV-vis spectrum of nitrate [Si(phen)2(OMe)2](NO3)2 film is explained by n 3 p* nature of these transitions. Significant error in prediction of charge transfer band energy is due to failure of TDDFT method to yield underestimated charge transfer electronic energies.
