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In this study, a variety of new triiron complexes were obtained by nucleophilic additions to vinyliminium ligands bridging between a diiron core and a ferrocene skeleton, and the reaction outcomes were elucidated using DFT calculations.

The μ-(amino)alkylidyne complex [Fe2Cp2(CO)2(μ-CO){μ-CNMe(CH2CHCH2)}]CF3SO3, [1]CF3SO3, reacted with NBu4CN in dichloromethane affording the μ-(cyano)(amino)alkylidene [Fe2Cp2(CO)2(μ-CO){μ-C(CN)N(Me)(CH2CHCH2)}], 2, in 91% yield. Decarbonylation of 2 by using Me3NO in acetone at room temperature yielded [Fe2Cp2(CO)(μ-CO){μ-κ3C-C(CN)N(Me)(CH2CHCH2)}], 3, containing a multidentate alkylidene-alkene ligand occupying both a bridging site and a terminal site, in admixture with the μ-(amino)alkylidyne cyanide product [Fe2Cp2(CN)(CO)(μ-CO){μ-CN(Me)(CH2CHCH2)}], 4. The reaction of the μ-(amino)alkylidyne imine complex [Fe2Cp2(CO)(μ-CO)(NHCPh2){μ-CN(Me)(CH2CHCH2)}]CF3SO3, [7]CF3SO3, with NBu4CN gave 3 with an optimized yield of 75% via imine elimination. According to DFT calculations, 3 is less stable than its geometric isomer 4 by 13.4 kcal mol-1 and quantitative conversion to 4 was achieved by refluxing a THF solution of 3 for 2 hours. No replacement of alkene coordination occurred upon treating 3 with CO or PPh3. The previously unknown compounds 2, 3, 4 and [7]CF3SO3 were fully characterized by analytical and spectroscopic techniques and the structure of 3 was elucidated by single crystal X-ray diffraction.

Diiron vinyliminium complexes constitute a large family of organometallics displaying a promising anticancer potential. The complexes [Fe2Cp2(CO)(μ-CO){μ-η1:η3-C(R3)C(R4)CN(R1)(R2)}]CF3SO3 (2a-c, 4a-d) were synthesized, assessed for their behavior in aqueous solutions (D2O solubility, Log Pow, stability in D2O/Me2SO-d6 mixture at 37°C over 48 h) and investigated for their antiproliferative activity against A2780 and A2780cisR ovarian cancer cell lines and the nontumoral one Balb/3T3 clone A31. Cytotoxicity data collected for 50 vinyliminium complexes were correlated with the structural properties (i.e. the different R1–R4 substituents) using the partial least squares methodology. A clear positive correlation emerged between the octanol–water partition coefficient and the relative antiproliferative activity on ovarian cancer cell lines, both of which appear as uncorrelated to the cancer cell selectivity. However, the different effects played by the R1–R4 substituents allow tracing guidelines for the development of novel, more effective compounds. Based on these results, three additional complexes (4p-r) were designed, synthesized and biologically investigated, revealing their ability to hamper thioredoxin reductase enzyme and to induce cancer cell production of reactive oxygen species.

The room temperature reactions with internal alkynes, RCCR, of the μ-allenyl acetonitrile complex [Ru

The room temperature reactions with internal alkynes, RCCR, of the mu-allenyl acetonitrile complex [Ru2Cp2(CO)(2)(NCMe){mu-eta(1):eta(2) -(CH)-H-1=C-2=(CMe2)-Me-3}]BF4 (1-NCMe), freshly prepared from the tricarbonyl precursor [Ru2Cp2(CO)(3){mu-eta(1):eta(2) -(CH)-H-1=C-2=(CMe2)-Me-3}]BF4, 1, proceeded with alkyne insertion into ruthenium-allenyl bond and allenyl-CO coupling, affording compounds [Ru2Cp2(CO2{mu-eta(2):eta(5)-C(R)C(R)(CHC2)-H-1((CMe)-Me-3=CH2)C(OH))}]BF4 (R = Ph, 2; R = CO2Me, 3; R = CO2Et, 4) in 83-94% yields. Deprotonation of 2-4 by triethylamine gave [Ru2Cp2(CO)(2){mu-eta(2):eta(5)-C(R)C(R)CHC(CMe=CH2)C(O)}] (R = Ph, 5; R = CO2Me, 6; R = CO2Et, 7) in 75-88% yields, and 2-4 could be recovered upon HBF4 center dot Et2O addition to 5-7. All the products, 2-7, were fully characterized by elemental analysis, IR and multinuclear NMR spectroscopy. The structure of 2 was ascertained by single crystal X-ray diffraction and investigated by DFT calculations, revealing a six-membered ruthenacycle with Shannon aromaticity index in line with related compounds. The formation of ruthenium-coordinated ruthenabenzenes from a preexistent diruthenium scaffold is a versatile but underdeveloped approach exploiting cooperative effects typical of a dimetallic core.

Dimetallic complexes are suitable platforms for the assembly of small molecular units, and the reactivity of bridging alkenyl ligands has been widely investigated to model C-C bond forming processes. Here, we report the unusual coupling of an alkenyl ligand, bridging coordinated on a diruthenium scaffold, with a series of alkynes, revealing two possible outcomes. The diruthenium complex [Ru2Cp2(Cl)(CO)(mu-CO) {mu-eta(1):eta(2)-C(Ph)=CH(Ph)}], 2, was prepared in two steps from [Ru2Cp2(CO)(2)(mu-CO){mu-eta(1):eta(2)-C(Ph)=CH (Ph)}]BF4, [1]BF4, in 69% yield. Then, the reaction of 2 with C-2(CO2Me)(2), promoted by AgCF3SO3 in dichloromethane, afforded in 51% yield the complex [Ru2Cp2(CO)(2){mu-eta(3):eta(2)-C(Ph)CH(Ph)C(CO2Me)C (CO2Me)}]CF3SO3, [3]CF3SO3, containing a ruthenacyclopentene-based hydrocarbyl ligand. On the other hand, 2 reacted with other alkynes and AgX salts to give the butadienyl complexes [Ru2Cp2(CO)(2){mu-eta(3):eta(2)-C(R)CH(R')C(Ph)C(Ph)}]X (R = R' = H, [4]BF4; R = R' = Me, [5]CF3SO3; R = R' = Ph, [6]CF3SO3; R = Ph, R' = H, [7]CF3SO3), in 42-56% yields. All products were characterized by IR and NMR spectroscopy, and by single crystal X-ray diffraction in the cases of 2, [3]CF3SO3 and [6]BF4. DFT calculations highlighted the higher stability of [4-7](+)- like structures with respect to the corresponding [3](+)-like isomers. It is presumable that [3](+)-like isomers initially form as kinetic intermediates, then undergo H-migration which is disfavoured in the presence of carboxylato substituents on the alkyne. Such hypothesis was supported by the computational optimization of the transition states for H-migration in the cases of R = R' = H and R = R' = CO2Me.

We report a screening study aimed to assess for the first time the air- and water-stability and the biological potential of simple metal-carbamates. These molecular metallic species are based on elements belonging to the groups 4–5, 7–9 and 11, and tin, and are easily available from inexpensive reagents. Complexes [Ag(O2CNEt2)] (13-Ag) and [Au(O2CNMe2)(PPh3)] (14-Au) resulted substantially stable in aqueous media and exhibited a potent in vitro cytotoxicity. Especially 13-Ag revealed a significant selectivity against the A549 lung adenocarcinoma and the A2780 ovarian cancer cell lines with respect to the noncancerous HEK293 cell line. Generation of ROS (reactive oxygen species) and mitochondrial membrane depolarization were recognized for 13-Ag and 14-Au; notwithstanding, the cell death mechanism is different in the two cases: apoptosis and cell cycle arrest in G0/G1 phase for 13-Ag; necroptosis and cell cycle arrest in S phase for 14-Au. Both 13-Ag and 14-Au are endowed with antibacterial activity, which is relatively stronger for 13-Ag towards Gram negative and for 14-Au towards Gram positive strains, respectively., La Caixa Foundation (LCF/PR/PR12/11070003), Consejería de Educación-Junta de Castilla y León-FEDER Funds (BU305P18), Ministerio de Ciencia, Innovación y Universidades (RTI2018-102040-B-100) and the University of Pisa (PRA_2020_39).

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.