Switching on Cytotoxicity of Water-Soluble Diiron Organometallics by UV Irradiation.

The diiron compounds [FeCp(CO)(μ-CO)(μ-CSEt)]CFSO, []CFSO, K[FeCp(CO)(CNCHCO)], K[], [FeCp(CO)(μ-CO)(μ-CNMe)]NO, []NO, [FeCp(CO)(PTA){μ-CNMe(Xyl)}]CFSO, []CFSO, and [FeCp(CO)(μ-CO){μ-η:η-C(4-CHCOH)CHCNMe}]CFSO, []CFSO, containing a bridging carbyne, isocyanoacetate, or vinyliminium ligand, were investigated for their photoinduced cytotoxicity. Specifically, the novel water-soluble compounds K[], []NO, and []CFSO were synthesized and characterized by elemental analysis and IR and multinuclear NMR spectroscopy. Stereochemical aspects concerning []CFSO were elucidated by H NOESY NMR and single-crystal X-ray diffraction. Cell proliferation studies on human skin cancer (A431) and nontumoral embryonic kidney (HEK293) cells, with and without a 10-min exposure to low-power UV light (350 nm), highlighted the performance of the aminocarbyne []NO, nicknamed (Nitrate-Iron-Aminocarbyne), which is substantially nontoxic in the dark but shows a marked photoinduced cytotoxicity. Spectroscopic (IR, UV-vis, NMR) measurements and the myoglobin assay indicated that the release of one carbon monoxide ligand represents the first step of the photoactivation process of , followed by an extensive disassembly of the organometallic scaffold.