Following a related review dating back to 2003, the present review discusses in detail the various synthetic, structural and reactivity aspects of metal species containing one or more carbamato ...ligands, representing a large family of compounds across all the periodic table. A preliminary overview is provided on the reactivity of carbon dioxide with amines, and emphasis is given to recent findings concerning applications in various fields.
Nitriles (N≡CR) are ubiquitous in coordination chemistry, yet literature studies on metal–nitrile bonding based on a multi-technique approach are rare. We selected an easily-available di-organoiron ...framework, containing both π-acceptor (CO, aminocarbyne) and donor (Cp = η5−C5H5) ligands, as a suitable system to provide a comprehensive description of the iron–nitrile bond. Thus, the new nitrile (2–12)CF3SO3 and the related imine/amine complexes (8–9)CF3SO3 were synthesized in 58–83% yields from the respective tris-carbonyl precursors (1a–d)CF3SO3, using the TMNO strategy (TMNO = trimethylamine-N-oxide). The products were fully characterized by elemental analysis, IR (solution and solid state) and multinuclear NMR spectroscopy. In addition, the structures of (2)CF3SO3, (3)CF3SO3, (5)CF3SO3 and (11)CF3SO3 were ascertained by single crystal X-ray diffraction. Salient spectroscopic data of the nitrile complexes are coherent with the scale of electron-donor power of the R substituents; otherwise, this scale does not match the degree of Fe → N π-back-donation and the Fe–N bond energies, which were elucidated in (2–7)CF3SO3 by DFT calculations.
Although ferrocene derivatives have attracted considerable attention as possible anticancer agents, the medicinal potential of diiron complexes has remained largely unexplored. Herein, we describe ...the straightforward multigram‐scale synthesis and the antiproliferative activity of a series of diiron cyclopentadienyl complexes containing bridging vinyliminium ligands. IC50 values in the low‐to‐mid micromolar range were determined against cisplatin sensitive and resistant human ovarian carcinoma (A2780 and A2780cisR) cell lines. Notable selectivity towards the cancerous cells lines compared to the non‐tumoral human embryonic kidney (HEK‐293) cell line was observed for selected compounds. The activity seems to be multimodal, involving reactive oxygen species (ROS) generation and, in some cases, a fragmentation process to afford monoiron derivatives. The large structural variability, amphiphilic character and good stability in aqueous media of the diiron vinyliminium complexes provide favorable properties compared to other widely studied classes of iron‐based anticancer candidates.
The power of two irons: Diiron vinyliminium complexes, easily available even in large scale, represent a new class of potential anticancer agents with multimodal action. These compounds offer a wide structural variability and possess appreciable solubility and good stability in aqueous solutions.
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•Aminocarbynes represent a peculiar class of ligands almost ubiquitous among transition metal elements.•They show various coordination modes adapting to different nuclearities, and a ...rich chemistry including unique reactivity patterns.•Each category of aminocarbyne complexes is presented discussing synthetic, reactivity, structural and spectroscopic features, and tracing comparisons with non-substituted carbyne ligands.
Following the former synthetic work on group 6 metal complexes, aminocarbyne (aminoalkylidyne) ligands have become popular across various transition metal groups. They are versatile ligands adapting to variable coordination modes (i.e. terminal, bridging and multibridging), metal oxidation states and co-ligands. They possess peculiar structural and reactivity features compared to nitrogen-lacking alkylidyne ligands and, especially when bridging coordinated to diiron bis-cyclopentadienyl frames, exhibit a rich chemistry enabling the construction of unusual organometallic species. The bonding, electronic and steric effects, structural and spectroscopic features and reactivity trends of aminocarbyne ligands are reviewed with reference to the distinct cases (nuclearity of the complex and coordination mode, nature of the metal element, and type of substituent(s) on the aminocarbyne).
A series of diiron/tetrairon compounds containing a S- or a Se-function (
-
,
-
,
-
,
), and the monoiron FeCp(CO){SeC
(NMe
)C
HC
(Me)} (
) were prepared from the diiron μ-vinyliminium precursors Fe
...Cp
(CO)( μ-CO){ μ-η
: η
-C
(R')C
HC
N(Me)(R)}CF
SO
(R = R' = Me,
; R = 2,6-C
H
Me
= Xyl, R' = Ph,
; R = Xyl, R' = CH
OH,
), via treatment with S
or gray selenium. The new compounds were characterized by elemental analysis, IR and multinuclear NMR spectroscopy, and structural aspects were further elucidated by DFT calculations. The unprecedented metallacyclic structure of
was ascertained by single crystal X-ray diffraction. The air-stable compounds (
,
-
,
-
,
) display fair to good stability in aqueous media, and thus were assessed for their cytotoxic activity towards A2780, A2780cisR, and HEK-293 cell lines. Cyclic voltammetry, ROS production and NADH oxidation studies were carried out on selected compounds to give insights into their mode of action.
A series of 16 novel diiron complexes of general formula Fe
Cp
(CO)(μ-CO){μ-η
:η
-C(R')C(R″)CN(R)(Y)}CF
SO
(
), bearing different substituents on the bridging vinyliminium ligand, was synthesized in ...69-95% yields from the reactions of diiron μ-aminocarbyne precursors with various alkynes. The products were characterized by elemental analysis, IR,
H and
C NMR spectroscopy; moreover the X-ray structures of
(R = Y = CH
Ph, R' = R″ = Me) and
(R = CH
CH=CH
, Y = R' = Me, R″ = H) were ascertained by single-crystal X-ray diffraction studies. NMR and UV-Vis methods were used to assess the D
O solubility, the stability in aqueous solution at 37 °C and the octanol-water partition coefficients of the complexes. A screening study evidenced a potent cytotoxicity of
against the A2780 cancer cell line, with a remarkable selectivity compared to the nontumoral Balb/3T3 cell line; complex
(R = Cy, Y = R' = R″ = Me) revealed as the most performant of the series. The antiproliferative activity of a selection of complexes was also assessed on the cisplatin-resistant A2780cisR cancer cell line, and these complexes were capable of inducing a significant ROS production. Moreover, ESI-MS experiments indicated the absence of interaction of selected complexes with cytochrome c and the potentiality to inhibit the thioredoxin reductase enzyme (TrxR).
The high toxicity of cyanide, along with its widespread industrial use, has fuelled interest in the development of analytical methods for its determination in complex matrices. In this study, we ...propose a novel approach for the measurement of total cyanide in soil samples based on single-step derivatization with pentafluorobenzyl bromide (F5Bn−Br) followed by quantitation with gas chromatography mass spectrometry in negative chemical ionization mode.
The reaction between CN− and F5Bn−Br resulted in the identification of several derivatives such as F5Bn−CN, (F5Bn)(F5Ph)CH−CN, and (F5Bn)2(F5Ph)C−CN. The relative proportion between such compounds was dependent on experimental conditions. When a 100 μL aliquot of an alkaline-aqueous extract was reacted with 700 μL of 1.3% F5Bn−Br in acetone, the tri-alkylated derivative was the most abundant. In such conditions a detection limit of 0.5 ng/g of CN− was attained.
Soil samples were initially spiked with an alkaline solution of K13C15N internal standard and suspended in 7.5% aqueous NaOH. Determination of total cyanide was achieved by digestion of the alkaline extract with H3PO4 to produce HCN which was then trapped in 0.1% NaOH in a sealed double vial system, followed by reaction with F5Bn−Br. Isotope dilution calibration was chosen for quantitation, and the validity of the novel method was demonstrated by analysis of soil Certified Reference Materials (CRMs) and by spike recovery tests.
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•A cost-effective, fast and simple method for determination of total cyanide in soil is presented.•A new micro-distillation strategy was developed overcoming the problems of a conventional distillation.•Negative chemical ionization-mass spectrometer has been exploited to obtain a high sensitivity and specificity.•High accuracy was attained for the analysis of certified reference materials with quadruple isotope dilution technique.
The reactions of the diiron aminocarbyne complexes Fe2Cp2(NCMe)(CO)(μ-CO){μ-CN(Me)(R)}CF3SO3 (R = Me, 1aNCMe; R = Cy, 1bNCMe), freshly prepared from the tricarbonyl precursors 1a–b, with primary ...amines containing an additional function (i.e., alcohol or ether) proceeded with the replacement of the labile acetonitrile ligand and formation of Fe2Cp2(NH2CH2CH2OR’)(CO)(μ-CO){μ-CN(Me)(R)}CF3SO3 (R = Me, R’ = H, 2a; R = Cy, R’ = H, 2b; R = Cy, R’ = Me, 2c) in 81–95% yields. The diiron-oxazolidinone conjugate Fe2Cp2(NH2OX)(CO)(μ-CO){μ-CN(Me)2}CF3SO3, 3, was prepared from 1a, 3-(2-aminoethyl)-5-phenyloxazolidin-2-one (NH2OX) and Me3NO, and finally isolated in 96% yield. In contrast, the one pot reactions of 1a-b with NHEt2 in the presence of Me3NO gave the unstable Fe2Cp2(NHEt2)(CO)(μ-CO){μ-CN(Me)(R)}CF3SO3 (R = Me, 4a; R = Cy, 4b) as unclean products. All diiron complexes were characterized by analytical and spectroscopic techniques; moreover, the behavior of 2a–c and 3 in aqueous media was ascertained.
A novel automated method based on sequential injection analysis (SIA), a non-segmented flow injection technique, was developed to evaluate glutathione S-transferase P1-1 (GST P1-1) activity in the ...presence of organometallic complexes with putative anticancer activity. The assay is based on the reaction of L-glutathione (GSH) and 1-chloro-2,4-dinitrobenzene (CDNB) in the presence of GST P1-1 to afford the GS-DNB conjugate and the reaction may be monitored by an increase in absorbance at 340 nm. A series of ruthenium, iron, osmium and iridium complexes were evaluated as GST P1-1 inhibitors by evaluating their half-maximal inhibitory concentration (IC
50
). An iridium compound displays the lowest IC
50
value of 6.7 ± 0.7 µM and an iron compound displays the highest IC
50
value of 275 ± 9 µM. The SIA method is simple to use, robust, reliable, and efficient and uses fewer reagents than batch methods and each analysis takes only 5 minutes.
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