Abstract
Ab initio geometries and Se NMR chemical shifts have been computed for Me2Se, H2Se, MeHSe, EtSeH, Se(SiH3, SeF4, SeF6, SeOF2, H2CSe, Me2CSe, SeCO, CSe2, and selenophene (C4H4Se). The mean absolute deviations from experimental δ(77Se) data are 97, 76, and 78 ppm at the IGLO-SCF/II//Expt., GIAO-SCF,
and GIAO-MP2/962+(d)//MP2/962(d) levels, respectively, over a range of 2800 ppm. For selenium chemical shift calculations, diffuse functions have to be included in the basis set in order to describe the Se lone pairs
properly, which provide the largest localized valence MO contributions to each Se shielding. A δ(77Se) value of ca. −40 ppm is predicted for gaseous EtSeH. Both SCF and MP2 methods fail to reproduce the
δ(77Se) chemical shift of Se42+ which requires a multireference description.