Preventing CO-Releasing Systems from Forming Precipitates and Tuning CO-Releasing Rate via Ligand Exchange Reaction

In this work, three water-soluble compounds (tiopronin, cysteamine, and mercaptoglycerol) which contain a thiol group have been used to initiate CO-release from a diiron hexacarbonyl complex [Fe-2(mu-SCH2CH(OH)CH2 (OH))(2)(CO)(6)] (1). To overcome forming precipitates during the CO-releasing process, we investigated using ethylene-diaminetetraacetic acid (EDTA) as the agent to solubilize products derived from the decomposition. Our results suggest that EDTA not only successfully prevents the CO-releasing system from forming precipitates, but also synergistically facilitates the CO-release from complex 1. Despite the fact that the chosen ligands possess a thiol functional group, their behaviors in promoting the CO-release