A Computational and Experimental Study of the Structures and Raman and 77Se NMR Spectra of SeX3+ and SeX2 (X = Cl, Br, I): FT-Raman Spectrum of (SeI3
文摘
The ability of MP2, B3PW91 and PBE0 methods to produce reliable predictions in structural and spectroscopicproperties of small selenium-halogen molecules and cations has been demonstrated by using 6-311G(d) andcc-pVTZ basis sets. Optimized structures and vibrational frequencies agree closely with the experimental information,where available. Raman intensities are also well reproduced at all levels of theory. Calculated GIAO isotropicshielding tensors yield a reasonable linear correlation with the experimental chemical shift data at each level oftheory. The largest deviations between calculated and experimental chemical shifts are found for selenium-iodinespecies. The agreement between observed and calculated chemical shifts for selenium-iodine species can beimproved by inclusion of relativistic effects using the ZORA method. The best results are achieved by addingspin-orbit correction terms from ZORA calculations to nonrelativistic GIAO isotropic shielding tensors. The calculatedisotropic shielding tensors can be utilized in the spectroscopic assignment of the 77Se chemical shifts of novelselenium-halogen molecules and cations. The experimental FT-Raman spectra of (SeI3)[AsF6] in the solid stateand in SO2(l) solution are also reported.