A study of the coordination environment in aqueous cadmium-thiol complexes by EXAFS spectroscopy: experimental vs. theoretical standards.

Using EXAFS, we investigated the changes in the local structure of Cd(II) complexes formed with a series of low-molecular-weight thiols at different thiol/cadmium stoichiometries. For dilute solutions, a comparison of theoretical and experimental standards proved the latter approach superior. The number of bound oxygen atoms decreased while the number of sulfur atoms increased as the thiol/cadmium ratios increased, indicating that up to four thiol compounds can bind to cadmium in aqueous solutions. The computer code FEFFIT was modified to employ experimental and theoretical standards with equal facility.