The monoiron anion fac -[Fe(CO) 3 I 3 ] − and its organic aminium salts: their preparation, CO-release, and cytotoxicity

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Four iron(II) carbonyl complexes, fac-[Fe (CO) 3 X 2 (py)] (X = I − , 1 and Br − , 3), fac-[{Fe (CO) 3 X 2 } 2 (bipy)] (X = I − , 2 and Br − , 4), were facilely synthesized by reacting cis-[Fe (CO) 4 X 2 ] (X = I − , Br −) with pyridine (py) and 4,4 0-dipyridine (bipy) ligands, respectively, in good yields (70%85%). These complexes were fully characterized, and the structures of Complexes 2 and 3 were crystallographically analyzed. In dimethyl sulfoxide, they decomposed rapidly to release carbon monoxide (CO), and in methanol, they showed better stability which allowed kinetically analyzing their decomposing behaviors. The selfdecomposing in methanol fitted first-order kinetics with a half-time ranging from several minutes to 1 h. Our results suggested that the ligand with great conjugation (bipy) and strong electron-donating capability (iodide) could stabilize the iron(II) carbonyl complexes. The decomposition of the iodo complexes (1 and 2) involved the production of iodine radicals. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assessments revealed that the efficacy against human bladder carcinoma cell line (RT112) is in the following trend: 1 > 2 > 3 > 4. The relatively strong efficacy of Complexes 1 and 2 is mainly contributed to the in situ generated iodine radicals. The combination of the cytotoxicity of the in situ generated radicals with the anticancer activity of CO as reported in literatures may lead to developing novel anticancer drugs with enhanced efficacy. K E Y W O R D S anticancer activity, carbon monoxide release and kinetics, iodine radical, iron carbonyl compounds, solvolysis Zhuming Guo and Jing Jin contributed equally to this work.

Section: Chemicals and Instrumentsmentioning

confidence: 99%

Section: Chemicals and Instrumentsmentioning

confidence: 99%

“…[36,43] NMR spectra were collected on a Varian 400MR (Agilent). [36,43] Elemental analyses were measured on Elementar Vario EL III.…”

Section: Chemicals and Instrumentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Four iron(II) carbonyl complexes containing both pyridyl and halide ligands: Their synthesis, characterization, stability, and anticancer activity

Guo

Jin

Xiao

et al. 2020

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Further exploration of the reaction between cis‐[Fe(CO)₄I₂] and alkylamines: An aminium salt of fac‐[Fe(CO)₃I₃]⁻ or an amine‐bound complex of fac‐[Fe(CO)₃I₂(NH₂R)]?

Guo

Xiao

et al. 2021

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Four new monoiron (II) tricarbonyl complexes with the amine bound, fac‐[Fe(CO)3I2(NH2R)] (R = Et, 1; nPr, 2; nBu, 3; nPent, 4), were reported using cis‐[Fe(CO)4I2] as the precursor. All the complexes 1–4 were structurally confirmed by various techniques such as ultraviolet–visible (UV–vis), Fourier transform infrared (FTIR), and nuclear magnetic resonance (NMR) spectra and elemental analysis of which complexes 1 and 2 are crystallographically determined. The reaction of the precursor with alkylamines proceeded in two main parallel pathways to form both aminium salts of fac‐[Fe(CO)3I3]− and the amine‐bound complexes (1–4). Their dominances altered with the reaction time. These complexes in DMSO undergo quick decomposition with complex 1 as the relatively most stable one (t1/2 = 7.3 min) although they are stable in solid status. Unlike the triiodo anion and pyridinyl analogs showing severe cytotoxicity due to the generation of iodine radical during the decomposition, no iodine radicals were detected from the fac‐[Fe(CO)3I2(NH2R)] complexes. Therefore, the cell viability of RT112 cells was not affected by the presence of the amine‐bound iron complex (1) up to 100 μmol L−1.

The reaction of nonacarbonyldiiron with 8‐alkynyloxyquinolines: Alkynyl activation, cyclization via C‐N bond formation, and C‐H bond cleavage

Luo,

Yu,

Chu

et al. 2024

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In this work, the reactions of nonacarbonyldiiron with 8‐alkynyloxyquinoline ligands (L1‐L3) and their resultant iron carbonyl complexes (1a, 1b, 2, and 3) are described. The complexes including the ligands were fully characterized by using a variety of spectroscopic techniques. The four complexes were also crystallographically determined. In the reactions, the quinoline N atom underwent cyclization to form a quinolinium skeleton while the C‐H bond of the quinoline at position 2 or the substituted methyl group was cleaved to form Fe‐C bond(s). Meanwhile, the alkynyl triple bond was reduced to a single bond (1a) or double bonds (1b, 2, and 3) to further coordinate the iron in σ‐bonds or η‐bonds. Particularly, pathways of hydrogenation (1a and 2) and/or dehydrogenation (1b and 3) were accompanied by the reactions. Moreover, the oxidation states of the iron centers in these complexes were identified through analyses of their bond formation, FTIR and NMR spectroscopic signals (1H NMR and DEPT‐135) in combination with their diamagnetic nature, that is, iron (0) for 2 and iron (I) for the rest of the diiron complexes.