Synthesis, Characterization and Biological Evaluation of New Manganese Metal Carbonyl Compounds That Contain Sulfur and Selenium Ligands as a Promising New Class of CORMs

Three new manganese carbonyl compounds with heavy atom donors were synthesized and their potential use as photoCORMS was evaluated. Interestingly, all compounds had an elusive binding mode, in which the ligands adopted a κ2-X coordination (where X = S or Se), confirmed both by X-ray crystallography and IR spectroscopy. The stability of the title compounds in the dark was determined by monitoring the changes in the UV spectra of the compounds in both dichloromethane and acetonitrile. These studies show that in coordinating solvents there is an exchange of the bromide bonded to the metal centre by a solvent molecule, which is evidenced by the changes in the UV and IR spectra and by DFT analysis. EDA and natural bond order analyses were conducted to evaluate the influence of the heavy atom donors in the first coordination sphere of the compounds. Photoexcitation at 380 nm demonstrated that all compounds showed release of all three COs, as seen in the photoproducts detected by IR spectroscopy. Furthermore, CO release was observed when the photoCORMs were incubated with living cells, and we observed a CO-dependent inhibition of cell viability.Funded under the Brazilian governmental agencies CNPq (PVE - 400210/2014-2), CNPq, and CERSusChem GSK/FAPESP (grant 2014/50249-8) grants for A. Neves, A. L. Braga, A. L. Amorim and R. A. Peralta, CAPES (Finance Code 001). We also thank the FAPESC, EU Horizon 2020 programme, Marie Skłodowska-Curie ITN GA no. 675007 and TWINN-2017 ACORN, GA no. 807281, the Royal Society (UF110046 and URF\R\180019 to G. J. L. B.), FCT Portugal (iFCT IF/00624/2015 to G. J. L. B. and PhD studentship SFRH/BD/115932/2016 to A. G.), and an ERC StG (GA no. 676832) for funding