Brief survey of diiron and monoiron carbonyl complexes and their potentials as CO-releasing molecules (CORMs)

Easily Available, Amphiphilic Diiron Cyclopentadienyl Complexes Exhibit in Vitro Anticancer Activity in 2D and 3D Human Cancer Cells through Redox Modulation Triggered by CO Release

“…[16] The presumed, controlled release of the iron centres (converted to iron oxide, see above) and carbon monoxide are two aspects that deserve attention with reference to the biological activity: note that the decay of ferrocene drug candidates into Fe II ions was previously associated to their cytotoxicity, [34] while the activity of various iron carbonyl complexes was correlated to CO dissociation in the physiological media. [35] …”

“…NMR spectra were recorded at 25°C on a Bruker Avance II DRX400 instrument equipped with a BBFO broadband probe. Chemical shifts (expressed in parts per million) are referenced to the residual solvent peaks [45] ( 1 H, 13 C) or to external standards 46 ( 14 N to CH 3 NO 2 ; 19 F to CFCl 3 , 35 Cl to 1 M NaCl in D 2 O, 31 13 C spectra were assigned with the assistance of 1 H{ 31 P}, 13 C DEPT 135, 1 H, 1 H COSY, 1 H- 13 C gs-HSQC and 1 H- 13 C gs-HMBC experiments. [47] CDCl 3 stored in the dark over Na 2 CO 3 was used for NMR analysis.…”

“…[16] The presumed, controlled release of the iron centres (converted to iron oxide, see above) and carbon monoxide are two aspects that deserve attention with reference to the biological activity: note that the decay of ferrocene drug candidates into Fe II ions was previously associated to their cytotoxicity, [34] while the activity of various iron carbonyl complexes was correlated to CO dissociation in the physiological media. [35] Next, the stability of the diiron compounds in a cell culture medium (DMEM) solution at 37°C, over a shorter time range (24 h), was assessed by 1 H NMR. Notably, a considerable fraction (70-88 %; Table S3) of the starting material was detected at the end of the experiment, with a limited formation of an orangebrown precipitate analogous to that described above.…”

“…Next, the dark red solution was moved on top of an alumina column (h 13, d 6 cm). Impurities were eluted with neat CH 2 Cl 2 and THF, then a red band containing 35 Cl NMR (CDCl 3 ): δ/ppm = 7.61 (Δν 1/2 = 266 Hz).…”

Toward Frameworks with Multiple Aligned and Interactive Fe(CO)3 Rotators: Syntheses and Structures of Diiron Complexes Linked by Two trans-Diaxial α,ω-Diphosphine Ligands Ar2P(CH2)nPAr2

“…They also establish diagnostic IR ν CO band patterns for the diiron complexes that allow structures to be verified for crystalline and noncrystalline samples as well as in solution where dynamic NMR properties may be probed. Although other potential applications for the new diiron and monoiron carbonyl compounds should not be overlooked, this work has provided a detailed foundation for further studies of interactive Fe­(CO) 3 /Fe­(CO) 3 rotators. Finally, extensions of these themes to triiron, tetrairon, and higher systems are easily envisioned, where there are intriguing possibilities for “water wheels” and other types of molecular machines.…”