Ammonia-based Magnus-type salts have long been recognized as highly insoluble coordination compounds whose one-dimensional chain structures give rise to unusual optical and electronic properties. Despite nearly two centuries of study and persistent debate, a unified understanding connecting structure, band energetics, and charge transport remains elusive. Here, we combine experimental and computational approaches to elucidate such relationships. A reproducible crystallization protocol enabled single-crystal X-ray diffraction characterization of [Pd(NH3)4][PdCl4] (2, Vauquelin salt), [Pt(NH3)4][PdCl4] (3), [Pd(NH3)4][PtCl4] (4), and [Pt(MeNH2)4][PdCl4] (5), along with new high-quality crystallographic data for [Pt(NH3)4][PtCl4] (1, Magnus green salt). Despite minimal structural variations across the series 1–5, periodic DFT calculations reveal pronounced modulation of band energies arising from cation–anion electrostatic effects and closed-shell metallophilic interactions. Single crystals of 2 were integrated into dual-gated field-effect transistors using nanolithography techniques, enabling the first unambiguous demonstration of ambipolar transport in an ammonia-based Magnus-type salt. The semiconductor band gap was experimentally determined to be 0.65 eV, closely matching the DFT prediction (0.61 eV, PBEsol functional), thereby establishing a quantitative link between crystal structure, band dispersion, and device-level electronic response.

Eleven new triiron compounds were synthesized in 25-90% yields from [Fe2Cp2(CO)2(μ-CO){μ-CNMe(Fc)}]+, Fc = CpFe(η5-C5H4), through substitution of one or both terminal CO ligands, or alkyne-coupling with the bridging aminocarbyne to afford vinyliminium derivatives. Products were characterized by IR and multinuclear NMR spectroscopy, and in selected cases by cyclic voltammetry, single crystal X-ray diffraction and DFT calculations. The compounds exhibited near millimolar water solubility, Log Pow values between -0.7 and >1.5, and notable stability in physiological-like solutions. They displayed potent cytotoxicity against five cancer cell lines with IC50 values reaching the nanomolar range, combined with high selectivity over normal fibroblasts. The mode of action appears linked to a marked decrease in intracellular reactive oxygen species. Fluorimetric studies on a representative complex revealed a low tendency to bind bovine serum albumin (EB) and a moderate ability to interact with DNA.

Ruthenium(ii) arene complexes represent a renowned platform to develop effective catalysts for a variety of organic transformations, including C-C bonding processes. On the other hand, isocyanides are overlooked ligands in the design of transition metal catalysts. Herein a panel of ruthenium(ii) arene isocyanide complexes were found to be versatile catalytic precursors for the dimerization/trimerization of aryl alkynes in aqueous medium. Fifteen compounds of general formula [RuX2(CNR)(eta 6-arene)] (X = Cl, I; R = alkyl or aryl; arene = C6H6, p-cymene, C6Me6) were prepared from the corresponding halido-bridged Ru dimers and the selected isocyanide according to optimized procedures, including examples with the simplest alkyl isocyanide (MeNC) and arene (C6H6). Next, two acetylide complexes of the type [RuCl(CCPh)(CNR)(eta 6-C6Me6)] were obtained by reaction of the corresponding dichlorido complexes with phenylacetylene and NaOH. In addition, a protocol for the thermally promoted p-cymene/MeCN substitution was optimized, giving access to hexacoordinate complexes with isocyanide and acetonitrile ligands, [RuCl2(MeCN)3(CNR)] (two examples). The Ru(ii) compounds, fourteen of which are unprecedented, were characterized by CHNS analyses, IR and NMR spectroscopy and X-ray diffraction in eight cases. The catalytic activity of the complexes was assessed, highlighting the role of the solvent, base, Ru loading, energy source and, more importantly, isocyanide/arene ligands to control the selectivity between dimerization and trimerization of phenylacetylene. Pointing to a sustainable process, a catalytic protocol involving Na2CO3 as a base, water as a solvent and a low Ru loading (1%) was applied for the dimerization/trimerization of a range of terminal alkynes, with [RuCl2(CNCy)(eta 6-p-cymene)] emerging as the best performing pre-catalyst. Combined IR, NMR and MS data were instrumental in the elucidation of the reactivity of the isocyanide-arene complexes with PhCCH/Na2CO3 and the formulation of a possible mechanism of pre-catalyst activation.

Tetranuclear rhodium carbonyl clusters are vital catalytic precursors; yet derivatives featuring bidentate phosphines are less common, due to the propensity for cluster fragmentation during synthesis. This study reports the successful isolation of five new heteroleptic species by reacting Rh4(CO)12 with various bidentate diphosphines under homogeneous conditions and at room temperature, namely the mono-substituted Rh4(CO)10(dppe) (1) and Rh4(CO)10(dppb) (3), the rare bis-substituted derivative Rh4(CO)8(dppe)2 (2), and the two unique dimeric assemblies {Rh4(CO)10(dpp-hexane)}2 (4) and {Rh4(CO)10(trans-dppe)}2 (5). The tetrahedral Rh4 core of the cluster precursor was preserved in all cases. The new compounds were characterized via infrared (IR) spectroscopy and single-crystal X-ray diffraction (SC-XRD). Furthermore, variable-temperature (VT) 31P{1H} NMR spectroscopy elucidated the dynamic behavior of the phosphorus atoms. This work reports a robust methodology for accessing stable, low-nuclearity rhodium phosphine clusters with tunable properties.

ABSTRACT A family of cobalt(II) bis‐trifluoroacetylcamphorate complexes ( 1–3 ), along with the diamagnetic zinc(II) analog 4 , has been synthesized and structurally characterized. The cobalt complexes exhibit solvent‐driven interconversion between cis ‐ and trans ‐octahedral geometries, coupled to labile solvent coordination. Their chiroptical response spans the UV, visible, NIR, and IR ranges and is highly sensitive to coordination geometry and solvent. In dilute solutions, vibrational circular dichroism (VCD) dissymmetry factors up to | g | ≈4 × 10 − 3 reflect vibronic coupling with low‐lying electronic states, a hallmark of high‐spin Co II centers. At concentrations above 30 mM in acetonitrile, spontaneous microcrystallization yields suspensions with an exceptional g value of approximately 0.2 at 1600 cm − 1 , that is the largest dissymmetry factor ever reported by VCD. This record value arises from the unprecedented concurrence of vibronic and aggregation‐induced enhancement in the same species, with aggregation providing the dominant contribution, as supported by crystallographic, spectroscopic, and computational evidence.

The clinical success of platinum-based drugs such as cisplatin, carboplatin, and oxaliplatin is still limited by severe side effects and the frequent emergence of resistance, highlighting the need for new metal-based anticancer agents. Among potential alternatives, iron is particularly attractive due to its abundance, biocompatibility, and essential biological roles. Despite this potential, complexes based on nonendogenous Fe(I) remain overlooked in cancer therapy. Here, we investigate four diiron(I) bis-cyclopentadienyl complexes bearing aminocarbyne, thiocarbyne, or vinyliminium ligands (FEAMP, FEACYP, FETPY, and FEVCY), previously identified as promising anticancer candidates. Their cytotoxic activity was first evaluated across several cancer cell lines, including breast adenocarcinoma, glioblastoma, and osteosarcoma, together with mechanistic studies focusing on reactive oxygen species (ROS) modulation and the activation of programmed cell-death pathways. Crucially, the study examines how the tumour microenvironment influences drug response. Since conventional 2D cultures often fail to capture the structural and biochemical complexity of tumours, the activity of the iron complexes was further evaluated comparing models of increasing biological relevance: monolayer of cells (MG63 cells), spheroids enriched in Cancer Stem Cells (CSCs Model) and a 3D scaffold-based osteosarcoma model (3D sOS Model) that better reproduces cell-cell and cell-matrix interactions. By integrating multiple experimental systems, this work highlights the critical role of microenvironmental complexity in shaping drug efficacy and provides new insight into the therapeutic potential of low-valent iron complexes as next-generation metal-based anticancer agents.

The reaction of a series of diiron mu-vinyliminium complexes, [Fe2Cp2(CO)(& micro;-CO){& micro;-eta 1-eta 2-C(R')CHCN(Me)(R)}] CF3SO3 (2a-h), with N2CHCO2Et and tBuOK in THF solution led to different outcomes depending on R and R', including formation of iron-coordinated six-membered ferracycles, hydrazone-vinyliminium ligands, alkyne deinsertion and fragmentation to monoiron products. A mixture of [FeCp2(CO)(& micro;-CO){& micro;-eta 1-eta 2-C(Cy)C{=NN--CH (CO2Et)}CN(Me)(Bn)}], 3c, and [FeCp{kappa Fe,k5C-FeCp(CO)C(O)C(CO2Et)C(NMeBn)CHC(Cy)}], 5c, was obtained for R = benzyl (Bn) and R' = cyclohexyl (Cy). Analogously, a mixture of [Fe2Cp2(CO)(& micro;-CO){& micro;-eta 1:eta 2-C(2-C6H4F)C (N(Me)N--CHCO2Et)C--NMe2}]CF3SO3, 4e, and [FeCp{kappa Fe,kappa 5C-FeCp(CO)C(OMe)C(CO2Et)C(NMe2)CHC(2C6H4F)}]CF3SO3, 6e, was recovered from R = Me, R' = 2-C6H4F after a final methylation step. The hydrazone complex [Fe2Cp2(CO)(& micro;-CO){& micro;-eta 1-eta 2-C(Cy)C(=NN--CHCO2Et)CN(Me)(Cy)}], 3d, was isolated along with impurities from R = R' = Cy. The mu-aminocarbyne complexes [Fe2Cp2{C(O)Me}(CO)(& micro;-CO){& micro;-CN(Me)(R)}] (R = Me, 7a; Bn, 7b) were isolated in 36-50 % yields from R = Me, Bn and R' = SiMe3 after alumina chromatography. The monoiron complex [FeCp(CO){C(NMeXyl)CHC(Tol)C(=O)}], 9, was formed in 55 % yield from R = metaxylyl (Xyl), R' = para-tolyl (Tol). All products were identified by IR and multinuclear NMR spectroscopy, and crystallographic characterization was performed on the ferrabenzene compound [FeCp{kappa Fe,kappa 5C-FeCp(CO)C (OMe)C(CO2Et)C(NMe2)CHC(Cy)}]CF3SO3, 6a, and on 7a.

A new family of pentamethylcyclopentadienyl (C5Me5, Cp*) iridium(III), rhodium(III), and ruthenium(III) complexes bearing bidentate 1,2‐dioxime ligands was developed as a promising platform for aqueous‐phase catalysis. A modular series of piano‐stool complexes of general formula [MX(η5‐Cp*)(κ2N‐dioxime)]+ (M = Ir, Rh, Ru; X = Cl, I) was obtained in excellent yields from inexpensive and readily available dioximes. Spectroscopic and crystallographic analyses showed that dioxime coordination strongly affects the acid–base behavior and water solubility of the complexes, while D2O speciation studies revealed sequential deprotonation equilibria (pKa1 ≈ 3.3; pKa2 ≈ 6.5–7.1) and halide lability, highlighting the dynamic behavior of these systems under catalytic conditions. The catalytic performance of the complexes was evaluated in amine H/D exchange using D2O as both solvent and deuterium source. Iridium derivatives, particularly [IrCp*X(κ2N‐nioxime)]+ (X = Cl, I), achieved >95% deuterium incorporation in pyrrolidine under optimized conditions. Cyclic, acyclic, and benzylic amines underwent efficient isotopic exchange, including incorporation at positions remote from the nitrogen, demonstrating broad but substrate‐dependent reactivity. These results identify Cp*Ir‐dioxime complexes as effective proton‐responsive catalysts for H/D exchange in water, and 1,2‐dioxime ligands provide a useful and tunable framework for the development of aqueous isotope‐exchange catalysis.

Electrochemical and spectroelectrochemical (SEC) techniques are widely employed in inorganic, coordination and organometallic chemistry. Nanoelectrochemistry and, in particular, the electrochemical study of atomically precise ligand protected metal nanoclusters has received great interest in the last decade. Molecular metal carbonyl clusters (MMCCs) are low valent atomically precise nanoclusters protected on the surface by a layer of CO ligands. Their metal cores may comprise from a few to some tens of metal atoms. Several electrochemical and SEC methods may be employed to study the redox properties of MMCCs. The reversible redox activity of MMCCs may originate from ad hoc conditions, in the case of lower nuclearity clusters, or incipient metallization of their metal core, as their sizes increase. Besides supplying information on the electronic and redox properties of MMCCs, electrochemical and SEC studies, supported by chemical, structural and computational investigation, can shed light on the structural changes induced by redox reactions of MMCCs. Moreover, the redox properties of MMCCs may be tuned by tailored chemical modifications. As a bonus, electrochemistry may be used to indirectly proof the hydride nature of larger MMCCs. Further information on the chemical properties of MMCCs may be gathered combining electrochemical, SEC, chemical, spectroscopic, structural and computational studies. This review will cover these different aspects of the electrochemical investigation of MMCCs, by exploring general principles and representative examples.

Diiron(I) bis-cyclopentadienyl complexes with a bridging aminocarbyne ligand feature an organometallic scaffold with established anticancer potential. Aiming to expand the structure-activity relationships, seven new compounds were synthesized by incorporating isocyanide ligands: [Fe2Cp2(CO)(CNFc)(μ-CO){μ-CNMe(R)}]CF3SO3 (Fc = [Fe(Cp)(η5-C5H4)], R = Me, 2a; cyclohexyl = Cy, 2b; p-methoxyphenyl = Anis, 2c; Cp = η5-C5H5) and [Fe2Cp2(CO)x(CNR')(1-x)(μ-CO){μ-CNMe(R)}]CF3SO3 (R = Cy, R' = Anis, x = 1, 3b or x = 2, 4b; R = Anis, R' = Cy, x = 1, 3c or x = 2, 4c). The products were isolated in 70%-85% yields and characterized by IR, NMR spectroscopy, and single crystal X-ray diffraction in one representative case. They display submillimolar water solubility, amphiphilic or moderately lipophilic character, and remarkable inertness in physiological-like solutions. While the ferrocenyl derivatives 2a-c exhibited only modest activity, 3 and 4 displayed potent cytotoxicity across a panel of six cancer cell lines, with IC50 values in the low micromolar range in most cases and in the nanomolar range for the NTERA-2 testis cell line. Moreover, 3b-c showed significant selectivity toward cancer cells and, along with 4b-c, retained a remarkable cytotoxic effect in 3D cell spheroids. Complexes 3b-c were effective in targeting cellular TrxR and increasing cellular ROS production.

Heteroleptic [Pt3n(CO)6n-x{P(OR)3}x]2- (n = 3-5; x = 1, 2; R = Me, Et, Ph) Chini clusters have been obtained upon reaction of homoleptic [Pt3n(CO)6n]2- (n = 3-5) species with increasing amounts of P(OR)3. In the case of P(OPh)3, the whole series of clusters [Pt3n(CO)6n-x{P(OPh)3}x]2- (n = 3-5; x = 1, 2) has been spectroscopically characterized. In contrast, by using the stronger σ-bases P(OMe)3 and P(OEt)3, it has been possible to identify only the species [Pt12(CO)22{P(OR)3}2]2-, [Pt9(CO)17{P(OR)3}]2- and [Pt9(CO)16{P(OR)3}2]2- (R = Me, Et). Generally speaking, 1-2 CO ligands may be selectively replaced by P(OR)3 ligands in homoleptic [Pt3n(CO)6n]2- (n = 3-5) clusters, whereas the addition of a third P(OR)3 ligand results in the elimination of a Pt3-triangle and the concomitant formation of a smaller [Pt3(n-1)(CO)6(n-1)]2- cluster that may be further substituted. The nature in solution of all the species has been elucidated by means of FT-IR, ESI-MS, 1H and 31P{1H} NMR spectroscopy. The molecular structures of [PMePh3]2[Pt9(CO)17{P(OPh)3}]·CH3COCH3, [PMePh3]2[Pt12(CO)22{P(OPh)3}2]·solv, [PMePh3]2[Pt12(CO)22{P(OMe)3}2], [PMePh3]2[Pt15(CO)28{P(OPh)3}2]·2CH3COCH3·C6H14 have been determined by single-crystal X-ray diffraction (SC-XRD). Computational studies have been carried out to get insights into the torsional isomers of [Pt12(CO)22{P(OR)3}2]2- (R = Me, Ph) and the positional isomers of [Pt9(CO)18-x{P(OMe)3}x]2- (x = 1-3) and related species.

The reaction of [NEt4]3 [HRu4(CO)12] (1) with three mole equivalents of [Cu(MeCN)4,BF4] and three mole equivalents of [NEt4]Br affords a nearly 1:1 mixture of [NEt4]3 [HRu4(CO)12(CuBr)3] (2) and [NEt4]2 [H2Ru8(CO)24Cu7Br3] (3). These two products can be separated owing to their different solubilities in organic solvents [NEt4].3 [HRu8(CO)24Cu6Br2] (4) has been obtained reacting 1, [Cu(MeCN)4,BF4] and [NEt4]Br with stoichiometry 1:1:3. In the absence of [NEt4]Br, 1 reacts with 3.5 mole equivalents of [Cu(MeCN)4,BF4] affording [Ru5(CO)15(CuMeCN)2] (5). The new clusters 2-5 have been fully characterized by FT-IR and 1H NMR spectroscopy, and their molecular structures elucidated by single-crystal X-ray diffraction (SC-XRD). Homometallic Ru-Ru and Cu-Cu as well as heterometallic Ru-Cu interactions have been computationally investigated by DFT methods.

A new family of pentamethylcyclopentadienyl (C 5 Me 5 , Cp*) iridium(III), rhodium(III), and ruthenium(III) complexes bearing bidentate 1,2‐dioxime ligands was developed as a promising platform for aqueous‐phase catalysis. A modular series of piano‐stool complexes of general formula [MX(η 5 ‐Cp*)(κ 2 N ‐dioxime)] + (M = Ir, Rh, Ru; X = Cl, I) was obtained in excellent yields from inexpensive and readily available dioximes. Spectroscopic and crystallographic analyses showed that dioxime coordination strongly affects the acid–base behavior and water solubility of the complexes, while D 2 O speciation studies revealed sequential deprotonation equilibria (pK a1 ≈ 3.3; pK a2 ≈ 6.5–7.1) and halide lability, highlighting the dynamic behavior of these systems under catalytic conditions. The catalytic performance of the complexes was evaluated in amine H/D exchange using D 2 O as both solvent and deuterium source. Iridium derivatives, particularly [IrCp*X(κ 2 N ‐nioxime)] + (X = Cl, I), achieved >95% deuterium incorporation in pyrrolidine under optimized conditions. Cyclic, acyclic, and benzylic amines underwent efficient isotopic exchange, including incorporation at positions remote from the nitrogen, demonstrating broad but substrate‐dependent reactivity. These results identify Cp*Ir‐dioxime complexes as effective proton‐responsive catalysts for H/D exchange in water, and 1,2‐dioxime ligands provide a useful and tunable framework for the development of aqueous isotope‐exchange catalysis.

The biological effects of diiron(I) aminocarbyne complexes [Fe2Cp2(CO)(L)(μ-CO){μ-CNR(R')}]+ originate from their intracellular disassembly, releasing reactive iron species. Herein, a systematic multitechnique investigation of the reactivity of tricarbonyl (L = CO) complexes in aqueous media was carried out. Well-soluble nitrate salts were prepared on a (multi)gram scale and characterized by IR, NMR, and XRD. The degradation process in water or DMEM was assessed after 72 h at 37 °C over a wide concentration range via 1H NMR and UV-vis. Results were integrated by pH, conductivity, UV-vis and 1H NMR measurements at 24 h intervals and ICP-OES. The process follows zero-order kinetics above mM concentration, with partial formation of the corresponding secondary amine (RR'NH) and cyclopentadiene. The slowly forming brown precipitates contain iron(III)-oxy(hydroxides) and minor organic/organometallic components as shown by CHNS analyses, IR, Raman and ESI-MS. Evaluating the effects of O2, ambient light, temperature, pH, Me3NO on the process via 1H NMR and UV-vis provided key mechanistic insights. Addition of 1,3,5-triaza-7-phosphadamantane (PTA) enabled trapping of the CO-substituted intermediate [Fe2Cp2(CO)(PTA)(μ-CO){μ-CNR(R')}]+. The pathway leading to total disruption of the coordination sphere was elucidated by DFT. Overall, these results lay the foundations for understanding the behavior of this promising class of anticancer metallodrugs in physiological settings.

The novel diiron amine complexes [Fe2Cp2(CO)(NH2R')(μ-CO){μ-CN(Me)(Cy)}]CF3SO3 [R' = H, 3; Cy, 4; CH2CH2NH2, 5; CH2CH2NMe2, 6; CH2CH2(4-C6H4OMe), 7; CH2CH2(4-C6H4OH), 8; Cp = η5-C5H5, Cy = C6H11 = cyclohexyl] were synthesized in 49-92 % yields from [Fe2Cp2(CO)2(μ-CO){μ-CN(Me)(Cy)}]CF3SO3, 1a, using a straightforward two-step procedure. They were characterized by IR and multinuclear NMR spectroscopy, and the structure of 7 was confirmed through X-ray diffraction analysis. Complexes 3-8 and the acetonitrile adducts [Fe2Cp2(CO)(NCMe)(μ-CO){μ-CN(Me)(R)}]CF3SO3 (R = Cy, 2a; Me, 2b; Xyl = 2,6-C6H3Me2, 2c) were assessed for their water solubility, octanol-water partition coefficient and stability in physiological-like solutions. The in vitro antiproliferative activity of 2a-c and 3-8 was tested on seven human cancer cell lines (A2780, A2780R, PC3, A549, MCF7, HOS and HT-29), while the selectivity was evaluated using normal MRC-5 cells. Overall, the complexes exhibited variable cytotoxicity, with IC50 values reaching the low micromolar range for 3, 7 and 8 in A2780 and A2780R cells, along with significant selectivity. Targeted experiments covered cell cycle modification, induction of cell death, mitochondrial membrane potential, ROS production and interaction with DNA and bovine serum albumin (BSA) as a model protein. The interaction of 3 with BSA was further investigated through computational studies. Results showed a negligible increase in intracellular ROS levels (except for 2b) and insignificant changes in mitochondrial membrane potential.

Metal vinylidenes are key intermediates in the activation of terminal alkynes. Previous studies concerning ruthenium ti6-arene complexes showed how the elusive vinylidenes are often transformed into more stable alkoxy (alkyl)carbene complexes upon reaction with alcohols, highlighting their electrophilicity. We reinvestigated the reactivity of terminal alkynes and alcohols with ruthenium(II) ti6-arene precursors and we found out new aspects of the formation and the reactivity of the alkoxy(carbene)complexes. First, the reactivity of ruthenium complexes bearing different ti6-arene, phosphane, halide co-ligands on the activation process of a series of arylalkynes have been examined. Under optimized conditions, a series of alkoxy(benzyl)carbene complexes of general formula [RuCl{C(OR')CH2(4-C5H4R)}(PR"3)(ti6-arene)]+ were obtained. Five compounds were isolated in 82-96 % yield and they were characterized by spectroscopic techniques and X-ray diffraction in three cases. Notably, these carbene complexes are the predominant reaction products even in presence of a large molar excess of water in the mixture for short reaction times. In fact, DFT calculations on a model system showed that the vinylidene intermediate, resulting from the Ru/ alkyne interaction, is preferentially attacked by MeOH instead of water. The subsequent formation of carbonyl complexes was assessed in various conditions by IR and NMR and four unprecedented and comparatively rare benzyl carbonyl complexes of general formula[Ru{CH2(4-C6H4R)}(CO)(PPh3)(ti6-arene)]+ are reported, including the crystal structure of one example. Next, an unprecedented reactivity study on selected alkoxy (benzyl)carbene complexes was carried out. Joint experimental and computational results indicate that these benzyl carbonyl complexes may actually arise from the reaction of the carbene complexes with water, a reactivity pathway that has never been considered in previous studies on the Ru-mediated hydrolytic cleavage of alkynes.

In this Frontier Article, the work carried out within our research group in Bologna in the field of surface decorated metal carbonyl clusters will be outlined and put in a more general context. After a short Introduction, clusters composed of a metal carbonyl core decorated on the surface by metal-ligand fragments will be analyzed. Both metal-ligand fragments behaving as Lewis acids and Lewis bases will be considered. Then, the focus will be moved to clusters composed of a naked metal core decorated and stabilized on the surface by metal-carbonyl fragments. The structure and bonding (where theoretical studies are available) of such surface decorated metal carbonyl clusters will be presented, and compared to atomically precise ligated nanoclusters.

Monocationic [RuCl(κ3-tpm)(L)(PPh3)]Cl (L = PPh3, 1; NCMe, 2; 1,3,5-triaza-7-phosphaadamantane (PTA), 3; phosphinoferrocene, 4; 3-methyl-pyrazole, 5; NH2(CH2)2OH, 6; NH2(CH2)2(4-C6H4OH) (tyramine), 7; cyclohexylamine, 8; NH2CH2CH2NH2, 9; tpm = tris-pyrazolylmethane) and bis-cationic ruthenium complexes [RuCl(κ3-tpm)(PPh3)(LL')][NO3]2 (LL' = ethylenediamine, 10; 1,10-phenanthroline, 11; 2-picolylamine, 12; N-phenyl-1-(2-pyridinyl)methanimine, 13) and [RuCl(κ3-tpm)(PPh3)(NCMe)2][NO3]2 (14) were evaluated for their anticancer potential. Complexes 4-9 and 13-14 are novel and were obtained in 72-98% yields from thermal exchange reactions of 1. They were characterized by IR and multinuclear NMR spectroscopy, and the solid-state structures of 4, 5, 6, 7, and 14 were determined by single-crystal X-ray diffraction. Complexes 3-8 and 10-14 were further examined for solubility and stability in aqueous media, and octanol/water partition coefficients. The complexes were assessed for their in vitro cytotoxicity on a panel of six cancer and two normal cell lines. Complex 1 and the ruthenium-ferrocenyl conjugate 4 revealed significant-to-moderate activity against the cancer cells, with IC50 values ranging from 1.8 to 25.2 μM. Mechanistic studies in A2780 cells included time-dependent cytotoxicity, intracellular ruthenium uptake, cell cycle analysis, autophagy induction, production of ROS (reactive oxygen species), and mitochondrial membrane potential measurements. Moreover, a detailed study was conducted to evaluate DNA and bovine serum albumin (BSA) binding capacity. Overall, the results revealed distinct potential mechanisms of action driven by ligand diversity, specifically mitochondrial uncoupling for 1 and 4, and apoptosis- and necrosis-induced cell death for 13 and 14.

The new diiron complexes [Fe2Cp2(CO)(L)(mu-CO){mu-CN(Me)(Cy)}]CF3SO3 (L = pyridine, 3a; 4-aminopyridine, 3b; 4-dimethylaminopyridine, 3c; 4-trifluoromethylpyridine, 3d; nicotinic acid, 4; Cp = eta 5-C5H5, Cy = C6H11 = cyclohexyl) were synthesized in moderate to high yields using two distinct synthetic routes from the precursors 1 (L = CO, for 4) and 2 (L = NCMe, for 3a-d), respectively. All products were characterized by IR and multinuclear NMR spectroscopy, and the structures of 3b and 3d were ascertained by X-ray diffraction studies. The behavior of the complexes in aqueous solutions (solubility, Log Pow, stability) was assessed using NMR and UV-Vis methods. The in vitro antiproliferative activity of 3a-c and 4 was evaluated against seven human cancer cell lines (A2780, A2780R, A549, MCF-7, PC3, HOS and HT-29) and one normal cell line (MRC-5), following 24 h of incubation (MTT test). Overall, 3-4 demonstrated stronger cytotoxicity than cisplatin, with 3c emerging as the most potent compound. The activity seems primarily linked to the inhibition of metabolic processes in the cancer cells, including depletion of reactive oxygen species (ROS) levels. However, subtle differences have been observed between the complexes, with 4 exerting its cytotoxicity through a distinct multimodal mechanism.

Metal carbonyl clusters, which can be seen as monodispersed and atomically defined nanoparticles stabilized by CO ligands, were used to prepare Ru-based catalysts with tuned basic properties to conduct the 5-hydroxymethylfurfural (HMF) aerobic oxidation to produce 2,5-furandicarboxylic acid (FDCA) in base-free conditions. The controlled decomposition of the carbonyl cluster [HRu3(CO)11]−, a methodology not yet applied to Ru catalysts for this reaction, on different supports focusing on controlling and tuning the basic properties of support allowed the formation of small Ru nanoparticles with a mean diameter of around 1 nm. The catalytic systems obtained resulted in more activity in the HMF oxidation than those prepared through a more common salt-impregnation technique, and the deposition of Ru nanoparticles on materials with basic functionalities has allowed avoiding the use of basic solutions in the reaction. The characterization by CO2-TPD of Mg(Al)O catalysts obtained from decomposition of layered double hydroxide hydrotalcites with different composition and activation has allowed disclosure of an important correlation between the selectivity of FDCA and the fraction of weak basic sites, which is decreased by the calcination treatment at increased temperature.