THE ELECTRONIC STRUCTURE OF NICKEL (II) ARYLCHALCOGENOLATE SCORPIONATES
The electronic structures of four nickel trispyrazolylborate (Tp) complexes were studied. These complexes feature coordination by aryl chalcogenide ligands (Eph) where E = O, S, Se, Te. Partial fluorescence yield Ni L2,3-edge X-ray absorption spectra were obtained to estimate vacant frontier d-orbital character as a function of chalcogen identity. Interpretation of these data was facilitated by computation including density functional theory (DFT) and combined active space self-consistent field (CASSCF) theory. Together, the experimental data obtained showed that frontier nickel 3d-orbital character decreased upon descending chalcogen group with Te, an exception to the trend. This can be attributed to spectral saturation effects leading to aberrant L2,3-edge intensities in the series, and thus conclusions concerning the electronic structures of these compounds require an alternative data collection strategy or saturation correction. Six compounds were sent to our lab for analysis of specified bonds using Raman Spectroscopy. Of the six, only three were viable in providing evidence in support of the hypothesized structure and ligand effects on signal obscuration. The other three samples were either unable to be resonance enhanced or experienced autofluorescence under laser excitation. These findings suggest that Raman Spectroscopy is useful for inorganic analysis, but its use is highly dependent on wavelength choice, sample concentration, and sample fluorescent properties particularly with proteins and polymers. The technique can also be costly and consume a considerable amount of space for proper setup of instrumentation.