Atomically precise rhodium-indium carbonyl nanoclusters: synthesis, characterization, crystal structure and electron-sponge features.

In this paper we present the investigation of the reactivity of [Rh(CO)] with InCl, with the aim of expanding the more general study that allowed us to obtain, among other species, the icosahedral [RhE(CO)] ( = 4 when E = Ge or Sn; = 3 when E = Sb or Bi) family of clusters. Indeed, the study resulted in the isolation and characterization of the analogous In-centred icosahedral [RhIn(CO)] nanocluster (1), which is isoelectronic and isostructural with the [RhE(CO)] congeners. During the course of the reaction two more new species, namely the octahedral [Rh(CO)InCl] (2) and the dimeric [{Rh(CO)InCl}] (3) have also been identified.

Triple -Functionalized Cations and Neutral Radicals of Enantiopure Diaza[4]helicenes.

Modulation of absorbance and emission is key for the design of chiral chromophores. Accessing a series of compounds absorbing and emitting (circularly polarized) light over a wide spectral window and often toward near-infrared is of practical value in (chir)optical applications. Herein, by late-stage functionalization on derivatives bridging triaryl methyl and helicene domains, we have achieved the regioselective triple introduction of electron-donating or electron-withdrawing substituents.

Oxaliplatin(IV) Prodrugs Functionalized with Gemcitabine and Capecitabine Induce Blockage of Colorectal Cancer Cell Growth-An Investigation of the Activation Mechanism and Their Nanoformulation.

The use of platinum-based anticancer drugs, such as cisplatin, oxaliplatin, and carboplatin, is a common frontline option in cancer management, but they have debilitating side effects and can lead to drug resistance. Combination therapy with other chemotherapeutic agents, such as capecitabine and gemcitabine, has been explored. One approach to overcome these limitations is the modification of traditional Pt(II) drugs to obtain new molecules with an improved pharmacological profile, such as Pt(IV) prodrugs.

Mixed valence triiron complexes from the conjugation of [FeFe] and [Fe] complexes intermolecular carbyne/alkyne coupling.

We present a new synthetic strategy for obtaining mixed-valence triiron complexes where the metal centers are bridged by a novel, highly functionalized hydrocarbyl ligand. The alkynyl-vinyliminium complexes [FeCp(CO)(μ-CO){μ-η:η-C(X-CCH)CHCNMe}]CFSO (X = 4-CH, [2a1]CF3SO3; X = (CH), [2a2]CF3SO3) were synthesized in almost quantitative yields from the aminocarbyne precursor [FeCp(CO)(μ-CO){μ-CNMe}]CFSO, [1a]CF3SO3, and the di-alkynes HCC-X-CCH. Then, the ferracycle [Fe(Cp)(CO){C(NMe)CHC(4-CHCCH)C(O)}], 4a1, was produced in 47% yield from the cleavage of [2a1]CF3SO3 promoted by pyrrolidine.

Triiron Complex with -Ferrocenyl Aminocarbyne Ligand Bridging a Diiron Core: DFT, Electrochemical, and Biological Insights.

The first -ferrocenyl aminocarbyne complex, [FeCp(CO)(μ-CO){μ-CN(Me)(Fc)}]CFSO (), was synthesized with an 88% yield from [FeCp(CO)], isocyanoferrocene (CNFc), and methyl triflate. The synthesis proceeded through the intermediate formation of [FeCp(CO)(CNFc)], . Multinuclear NMR experiments revealed the presence of cis and trans isomers for in organic solvents, in agreement with DFT outcomes.

Anticancer Potential of Diruthenium Complexes with Bridging Hydrocarbyl Ligands from Bioactive Alkynols.

Diruthenacyclopentenone complexes of the general composition [RuCp(CO){μ-η:η-CH═C(C(OH)(R))C(═O)}] (-; Cp = η-CH) were synthesized in 94-96% yields from the reactions of [RuCp(CO){μ-η:η-C(Ph)═C(Ph)C(═O)}] () with 1-ethynylcyclopentanol, 17α-ethynylestradiol, and 17-ethynyltestosterone, respectively, in toluene at reflux. Protonation of - by HBF afforded the corresponding allenyl derivatives [RuCp(CO){μ-η:η-CH═C═R}]BF (-) in 85-93% yields. All products were thoroughly characterized by elemental analysis, mass spectrometry, and IR, UV-vis, and nuclear magnetic resonance spectroscopy.

Highly Reduced Ruthenium Carbide Carbonyl Clusters: Synthesis, Molecular Structure, Reactivity, Electrochemistry, and Computational Investigation of [RuC(CO)].

The reaction of [RuC(CO)] () with NaOH in DMSO resulted in the formation of a highly reduced [RuC(CO)] (), which was readily protonated by acids, such as HBF·EtO, to [HRuC(CO)] (). Oxidation of with [CpFe][PF] or [CH][BF] in CHCN resulted in [RuC(CO)(CHCN)] (), which was quantitatively converted into after exposure to CO atmosphere. The reaction of with a mild methylating agent such as CHI afforded the purported [RuC(CO)(COCH)] ().

Adding Diversity to a Diruthenium Biscyclopentadienyl Scaffold via Alkyne Incorporation: Synthesis and Biological Studies.

We report the synthesis and the assessment of the anticancer potential of two series of diruthenium biscyclopentadienyl carbonyl complexes. Novel dimetallacyclopentenone compounds (-) were obtained (45-92% yields) from the thermal reaction (PhCCPh exchange) of [RuCp(CO)(μ-CO){μ-η:η-C(Ph)═C(Ph)C(═O)}], , with alkynes HCCR [R = CHFeCp (Fc), 3-CH(Asp), 2-naphthyl; Cp = η-CH, Asp = OC(O)-2-CHC(O)Me]. Protonation of - by HBF afforded the corresponding μ-alkenyl derivatives -, in 40-86% yields.

From M to M, M and M molecular alloy Pt-Ni carbonyl nanoclusters: selective growth of atomically precise heterometallic nanoclusters.

Heterometallic Chini-type clusters [PtNi(CO)] ( = 0-6) were obtained by reactions of [Pt(CO)] with Ni-clusters such as [Ni(CO)], [Ni(CO)] and [HNi(CO)], or from [Pt(CO)] and [Ni(CO)]. The Pt/Ni composition of [PtNi(CO)] ( = 0-6) depended on the nature of the reagents employed and their stoichiometry. Reactions of [Pt(CO)] with [Ni(CO)] and [HNi(CO)], as well as reactions of [Pt(CO)] with [Ni(CO)], [Ni(CO)] and [HNi(CO)], afforded [PtNi(CO)] ( = 0-9) species.

Synthesis, Characterization and Photoactivation Studies on the Novel Pt(IV)-Based [Pt(OCOCH)(phterpy)] Complex.

Photoactivatable Pt(IV) prodrugs represent nowadays an intriguing class of potential metal-based drugs, endowed with more chemical inertness in their oxidized form and better selectivity for the target with respect to the clinically established Pt(II) compounds. In fact, they have the possibility to be reduced by light irradiation directly at the site of interest. For this reason, we synthesized a new Pt(IV) complex, [Pt(OCOCH)(4'-phenyl-2,2':6',2''-terpyridine)][CFSO] (), that is well soluble in aqueous medium and totally unreactive towards selected model biomolecules until its reduction.

Atomically Precise Platinum Carbonyl Nanoclusters: Synthesis, Total Structure, and Electrochemical Investigation of [Pt(CO)] Displaying a Defective Structure.

The molecular Pt nanocluster [Pt(CO)] () was obtained by thermal decomposition of [Pt(CO)] in tetrahydrofuran under a H atmosphere. The reaction of with increasing amounts of HBFEtO afforded the previously reported [Pt(CO)] () and [Pt(CO)] (). The new nanocluster was characterized by IR and UV-visible spectroscopy, single-crystal X-ray diffraction, direct-current superconducting quantum interference device magnetometry, cyclic voltammetry, IR spectroelectrochemistry (IR SEC), and electrochemical impedance spectroscopy.

Atomically Precise Ni-Pd Alloy Carbonyl Nanoclusters: Synthesis, Total Structure, Electrochemistry, Spectroelectrochemistry, and Electrochemical Impedance Spectroscopy.

The molecular nanocluster [NiPd(CO)] ( = 0.41) () was obtained from the reaction of [NMe(CHPh)][Ni(CO)] with 0.8 molar equivalent of [Pd(CHCN)][BF] in tetrahydrofuran (thf).

Heterometallic rhodium clusters as electron reservoirs: Chemical, electrochemical, and theoretical studies of the centered-icosahedral [RhE(CO)] atomically precise carbonyl compounds.

In this paper, we present a comparative study of the redox properties of the icosahedral [RhE(CO)] (n = 4 when E = Ge or Sn and n = 3 when E = Sb or Bi) family of clusters through in situ infrared spectroelectrochemistry experiments and density functional theory computational studies. These clusters show shared characteristics in terms of molecular structure, being all E-centered icosahedral species, and electron counting, possessing 170 valence electrons as predicted by the electron-counting rules, based on the cluster-borane analogy, for compounds with such metal geometry. However, in some cases, clusters of similar nuclearity, and beyond, may show multivalence behavior and may be stable with a different electron counting, at least on the time scale of the electrochemical analyses.

Tetrasubstituted Selenophenes from the Stepwise Assembly of Molecular Fragments on a Diiron Frame and Final Cleavage of a Bridging Alkylidene.

A series of 2,3-dicarboxylato-5-acetyl-4-aminoselenophenes, -, was obtained via the uncommon assembly of building blocks on a diiron platform, starting from commercial [FeCp(CO)] through the stepwise formation of diiron complexes [-]CFSO, -, and -. The selenophene-substituted bridging alkylidene ligand in - is removed from coordination upon treatment with water in air under mild conditions (ambient temperature in most cases), affording - in good to excellent yields. This process is highly selective and is accompanied by the disruption of the organometallic scaffold: cyclopentadiene (CpH) and lepidocrocite (γ-FeO(OH)) were identified by NMR and Raman analyses at the end of one representative reaction.

Redox active Ni-Pd carbonyl alloy nanoclusters: syntheses, molecular structures and electrochemistry of [NiPd(CO)] (x = 0.62), [NiPd(CO)] (x = 0.09) and [NiPd(CO)] (x = 0.27).

A redox active Ni-Pd alloy nanocluster [NiPd(CO)] (x = 0.62) ([1]) was obtained from the redox condensation of [NBu][Ni(CO)] with 0.7-0.

Rh-Sb Nanoclusters: Synthesis, Structure, and Electrochemical Studies of the Atomically Precise [RhSb(CO)] and [RhSb(CO)] Carbonyl Compounds.

The reactivity of [Rh(CO)] with SbCl has been deeply investigated with the aim of finding a new approach to prepare atomically precise metalloid clusters. In particular, by varying the stoichiometric ratios, the reaction atmosphere (carbon monoxide or nitrogen), the solvent, and by working at room temperature and low pressure, we were able to prepare two large carbonyl clusters of nanometer size, namely, [RhSb(CO)] and [RhSb(CO)]. A third large species composed of 28 metal atoms was isolated, but its exact formulation in terms of metal stoichiometry could not be incontrovertibly confirmed.

Anticancer Potential of Diiron Vinyliminium Complexes.

Invited for the cover of this issue is the group of Fabio Marchetti at the Università di Pisa and Paul J. Dyson at Ecole Polytechnique Fédérale de Lausanne (EPFL). Read the full text of the article at 10.

Anticancer Potential of Diiron Vinyliminium Complexes.

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. IC values in the low-to-mid micromolar range were determined against cisplatin sensitive and resistant human ovarian carcinoma (A2780 and A2780cisR) cell lines.

Photocytotoxic Pt(iv) complexes as prospective anticancer agents.

The use of Pt(iv) complexes as potential anticancer drugs is attractive, because they have higher stability and less side effects than Pt(ii) compounds. Moreover, some Pt(iv) complexes can also be activated with light, opening an avenue to photochemotherapy. Our purpose is to widen the library of photoactivatable Pt(iv)-based prodrugs and here we report on the oxidation of the Pt(ii) compound [PtCl(4'-phenyl-2,2':6',2''-terpyridine)][CFSO] (1) with PhICl or HO.

Circularly-Polarized Electrochemiluminescence from a Chiral Bispyrene Organic Macrocycle.

The first observation of circular polarization of electrochemiluminescence (ECL) from a purely organic derivative is reported. A bispyrene scaffold mounted on a constrained polyether macrocycle displaying intense excimer fluorescence and highly circularly-polarized (CP) photoluminescence has been selected for this purpose. The compound displays an ECL dissymmetry factor of about |8×10 |, which is in good agreement with the corresponding photoluminescence value.

Controlled Dissociation of Iron and Cyclopentadienyl from a Diiron Complex with a Bridging C Ligand Triggered by One-Electron Reduction.

The one-electron reduction of a diiron cationic complex revealed unique features: cleavage of the diiron structure occurred despite a multidentate bridging C ligand and was accompanied by the clean dissociation of one η-cyclopentadienyl ring and one iron as isolated units. Thus, the iron(II)-iron(II) μ-vinyliminium complex [FeCp(CO)(μ-CO){μ-η:η-C(Et)CHCN(Me)(Xyl)}][SOCF] ([1a]SOCF) reacted with cobaltocene in tetrahydrofuran (THF), affording the iron(II) vinylaminoalkylidene [FeCp(CO){CN(Me)(Xyl)CHC(Et)C(═O)}] (2a) in 77% yield relative to the C ligand. Analogously, [FeCp(CO){CN(Me)(Xyl)CHC(CHOH)C(═O)}] (2b) was obtained in 64% yield from the appropriate diiron precursor and CoCp.

α-Diimines as Versatile, Derivatizable Ligands in Ruthenium(II) p-Cymene Anticancer Complexes.

α-Diimines are among the most robust and versatile ligands available in synthetic coordination chemistry, possessing finely tunable steric and electronic properties. A series of novel cationic ruthenium(II) p-cymene complexes bearing simple α-diimine ligands, [(η- p-cymene)RuCl{κ N-(HCNR)}]NO (R = Cy, [1]NO; R = 4-CHOH, [2]NO; R = 4-CHOH, [3]NO), were prepared in near-quantitative yields as their nitrate salts. [2]NO displays high water solubility.

Molecular Nickel Phosphide Carbonyl Nanoclusters: Synthesis, Structure, and Electrochemistry of [NiP(CO)] and [HNiP(CO)] (n = 4 and 5).

The reaction of [NEt][Ni(CO)] in thf with 0.5 equiv of PCl affords the monophosphide [NiP(CO)] that in turn further reacts with PCl resulting in the tetra-phosphide carbonyl cluster [HNiP(CO)]. Alternatively, the latter can be obtained from the reaction of [NEt][Ni(CO)] in thf with 0.

Allowing the direct interaction of N-aryl α-diimines with a high valent metal chloride: one-pot WCl-promoted formation of quinoxalinium salts.

The full potential of a high valent metal chloride as both a chlorinating and an oxidative agent was explored by allowing WCl to react with N-(2,6-diisopropylphenyl) α-diimines, in CHCl at room temperature. These α-diimines underwent unprecedented conversion to quinoxalinium cations via intramolecular C-N coupling.

One pot conversion of benzophenone imine into the relevant 2-aza-allenium.

Interaction of common imines with WCl in organic solvents revealed very unusual features in the context of imine chemistry. PhC[double bond, length as m-dash]NH was converted in one pot into the 2-aza-allenium species [PhC[double bond, length as m-dash]N[double bond, length as m-dash]CPh]via N release, with [PhC[double bond, length as m-dash]NH] being a co-product. PhCH[double bond, length as m-dash]NBu underwent C-H bond activation resulting in the formation of [C[triple bond, length as m-dash]N] containing derivatives, together with [PhCH[double bond, length as m-dash]NHBu].