| Solid-state nuclear magnetic resonance permits access to the orientation-dependent NMR interaction tensors. A review of the solid-state 77Se NMR literature introduces areas of active research and places the presented experimental work into context. A comprehensive investigation of selenium chemical shift tensors provides a theoretical foundation using density functional theory for the level of relativistic theory, via the zeroth order regular approximation, required to reproduce experimentally determined values and trends. The selenium chemical shift tensors for a number of organoselenium, organophosphine selenide, and inorganic selenium systems are reported for the first time. Multinuclear magnetic resonance investigations of iminobis(dialkylphosphine chalcogenide) systems, HN(R2PE)2 (E = O, S, Se; R = Ph, iPr), together with their respective calculated values demonstrate the sensitivity of the selenium chemical shift tensor to hydrogen bonding and disorder within their solid-state structures. Indirect one-bond selenium-phosphorus coupling constants, 1J(77Se, 31P)iso, are diagnostic with respect to the presence of an acidic N-H proton. The magnitudes of 1J( 77Se,31P)iso for the HN(R2PSe) 2 (R = Ph, iPr) species, > 700 Hz, are on the order of 200 Hz larger than those found for [N(iPr2PSe) 2]- systems. The study of metal(II) tetraisopropyldiselenoimido-diphosphinato complexes, M[N(iPr2PSe)2]2, by solid-state NMR presents a novel non-symmetric inorganic X-Se-Y moiety for solid-state 77Se NMR investigation. The characterized M-Se-P linkages are members of six-membered, MSe2P2N, rings. The pseudo-boat or distorted chair conformations of the heterocyclic rings, commonly encountered in M n+[N(R2PSe)2]n systems, have been differentiated by solid-state 77Se NMR. The selenium chemical shift tensors for the pseudo-boat MSe2P2N rings possess spans, Ω = δ11 – δ33, that are on the order of 100-200 ppm larger than those from rings with a distorted chair conformation. Calculated orientations for the selenium chemical shift tensors are also found to differ depending on the conformation of the heterocyclic ring. The selenium chemical shift tensor for the central selenium in the square-planar complex Se[N(iPr2PSe)2]2 was described by qualitative molecular orbital theory, and its computation was found to require spin-orbit relativistic corrections in order to accurately reproduce the principal components, δii. The largest magnitudes reported for 1J(77Se, 77Se)iso and 1J( 125Te,77Se)iso were found for the Se[N( iPr2PSe)2]2 and Te[N(iPr 2PSe)2]2 complexes, respectively. |
