Search

The new diiron(I) complexes [Fe2Cp2(μ‐CO){μ‐k3C,kN‐C(R1)C(R2)C(CN)NMe(R)}], 3 a–o (R=alkyl or 4‐C6H4OMe; R1=alkyl, aryl, ferrocenyl (Fc), thiophenyl, CO2Me or SiMe3; R2=H, Me or CO2Me) were synthesized in moderate to high yields from the thermal decarbonylation of the bis‐carbonyl precursors 2 a–o, and were structurally characterized by IR and NMR spectroscopy, and single crystal X‐ray diffraction in four cases. Electrochemical behavior of one complex was also investigated. Complexes 3 a–o comprise a highly functionalized, multisite amino‐(cyano)allylidene ligand, including metal coordination of a tertiary amine group. Selected complexes displayed negligible to moderate catalytic activity in CO2/propylene oxide coupling, working under ambient conditions. Additionally, they were investigated as catalysts for the conversion of benzaldehyde to the corresponding borate ester 6 a, using pinacolborane (HBpin) as the borylating agent. Most complexes achieved good conversions at room temperature with 1 % catalyst loading, and data highlight the significant influence of the multisite ligand substituents on the catalytic performance. Notably, complex 3 m (featuring R=4‐methoxyphenyl, R1=Fc, R2=H) displayed the highest activity and effectively catalyzed the hydroboration of various aldehydes and ketones. A plausible mechanistic cycle involves metal coordination of the carbonyl substrate, its activation being possibly facilitated by intramolecular interactions. [ABSTRACT FROM AUTHOR]

While ruthenium(II) arene complexes have been widely investigated for their potential in catalytic transfer hydrogenation, studies on homologous compounds replacing the arene ligand with the six‐electron donor tris(1‐pyrazolyl)methane (tpm) are almost absent in the literature. The reactions of [RuCl(κ3‐tpm)(PPh3)2]Cl, 1, with a series of nitrogen ligands (L) proceeded with selective PPh3 mono‐substitution, affording the novel complexes [RuCl(κ3‐tpm)(PPh3)(L)]Cl (L=NCMe, 2; NCPh, 3; imidazole, 4) in almost quantitative yields. Products 2–4 were fully characterized by IR and multinuclear NMR spectroscopy, moreover the molecular structure of 4 was ascertained by single crystal X‐ray diffraction. Compounds 2–4 were evaluated as catalytic precursors in the transfer hydrogenation of a series of ketones with isopropanol as the hydrogen source, and 2 exhibited the highest activity. Extensive NMR experiments and DFT calculations allowed to elucidate the mechanism of the transfer hydrogenation process, suggesting the crucial role played by the tpm ligand, reversibly switching from tri‐ to bidentate coordination during the catalytic cycle. [ABSTRACT FROM AUTHOR]

The catalytic activity of a series of diiron complexes based on the {Fe2Cp2(CO)x} core (x = 2–3) and containing a bridging aminocarbyne ligand was screened in transfer hydrogenation reaction of cyclohexanone from isopropanol. The series includes cationic tricarbonyl complexes, [1a–d]CF3SO3, and neutral derivatives obtained by substitution of one carbonyl with hydride (2a–c), cyanide (3a–d) or chloride (4a) ligands. The novel compounds 2a–b, 3a–b and 4a were characterized by analytical and spectroscopic techniques, and the single crystal X‐ray structure of one isomer of 4a was determined. In general, diiron complexes exhibited a moderate activity in combination with potassium hydroxide; [Fe2Cp2(CN)(CO)(μ‐CO){μ‐CN (Me)(4‐C6H4OMe)}], 3a, emerged as the best catalyst, and the study of its activity was extended to a range of other ketones. DFT calculations suggest an unusual carbyne‐centred mechanism, and the better performance displayed by 3a is ascribable to the stabilizing effect provided by the cyanide co‐ligand, which is experimentally supported by IR analyses. [ABSTRACT FROM AUTHOR]

The similar reactivity of lanthanides generally leads to statistically populated polynuclear complexes, making the rational design of ordered hetero‐lanthanide compounds extremely challenging. Here we report on the site selectivity in hetero‐lanthanide tetranuclear complexes afforded by the relatively simple ditopic pyterpyNO ligand (4'‐(4‐pyridil)‐2,2':6',2"‐terpyridine N‐oxide). The sequential room temperature reaction of RE2(tta)6(pyterpyNO)2 (where RE=Y, (1); Eu, (2), Dy, (3) Htta=2‐thenoyltrifluoroacetone) with La(tta)3dme (dme=dimethoxyethane) yielded Y2La2(tta)12(pyterpyNO)2 (4), Dy2La2(tta)12(pyterpyNO)2 (5) and Eu2La2(tta)12(pyterpyNO)2 (6). Single crystals X‐ray diffraction studies showed that 4, 5 and 6 are isostructural, featuring a tetranuclear structure with two different metal coordination sites with coordination numbers 8 (CN8) and 9 (CN9). The two smaller cations are mainly bridged by the O‐donor atoms of the NO groups of two pyterpyNO ligands (CN8), while the larger lanthanum centres are bound by a terpyridine unit (CN9). Size selectivity has been studied with structural and magnetic studies in the solid state and through 19F NMR and photoluminescence studies in solution, showing a direct dependence on the difference of ionic radii of the ions and yielding a 91 % selectivity for 4. Furthermore, 19F NMR, X‐ray and PL studies pointed out that the nature of the product is independent from the synthetic route for compound Eu2Y2(tta)12(pyterpyNO)2 (7), keeping the ion selectivity also for a self‐assembly reaction. Unexpectedly, these studies have evidenced that selectivity is not exclusively governed by electrostatic interactions related to size dimensions. [ABSTRACT FROM AUTHOR]

This article, published in ChemCatChem, discusses the synthesis of new diiron organometallic complexes with different properties. The complexes were found to have catalytic activity in hydroboration reactions, converting carbonyl compounds into organoboronates under mild conditions. The researchers highlight the importance of the diiron scaffold and the amino pendant of the hydrocarbyl ligand in this process. The article provides more detailed information on the synthesis and catalytic activity of these complexes. [Extracted from the article]

Novel titanium alkoxide‐carbamate complexes, i. e. [Ti(OiPr)2(O2CNR2)2]m (R=Et, 1; R=iPr, 2; R=Bn=CH2Ph, 3), were synthesized in 87–94 % yields by using two distinct synthetic approaches, i. e. the reaction of [Ti(OiPr)4] with [Ti(O2CNR)4] (1 : 1 molar ratio) in dichloromethane solution, and the addition of [Ti(OiPr)4] to amine/CO2 mixture in toluene (amine/Ti ratio=2). The liquid products 1–3 were characterized by elemental analysis, IR and NMR spectroscopy, and the structure of 1 was optimized by DFT calculations. Combined, experimental and theoretical outcomes suggest a trinuclear structure for 1–3, with the carbamates acting as bridging bidentate ligands. Compound 2 revealed the most effective of the series in promoting the oxidation of a series of organic sulfides into the corresponding sulfones, working generally better than 1 and 3 and the homoleptic counterparts [Ti(OiPr)4] or [Ti(O2CNEt2)4]. However, [Ti(OiPr)4] exhibited the best performance in the conversion of tetrahydrothiophene to tetrahydrothiophene 1,1‐dioxide, instead [Ti(O2CNEt2)4] was the most suitable catalyst for the mono‐oxygenation of dibenzylsulfide. NMR and DFT studies indicate that mononuclear bis‐methanol adducts, bearing the solvent molecules trans‐located with respect to the isopropoxides, are plausible active species in the catalytic cycle. [ABSTRACT FROM AUTHOR]

A straightforward two‐step procedure via single CO removal allows the conversion of commercial [Fe2Cp2(CO)4] into a range of amphiphilic and robust ionic complexes based on a hybrid aminocarbyne/iminium ligand, [Fe2Cp2(CO)3{CN(R)(R')}]X (R, R'=alkyl or aryl; X=CF3SO3 or BF4), on up to multigram scales. Their physicochemical properties can be modulated by an appropriate choice of N‐substituents and counteranion. Tested against a panel of human cancer cell lines, the complexes were shown to possess promising antiproliferative activity and to circumvent multidrug resistance. Interestingly, most derivatives also retained a significant cytotoxic activity against human cancer 3D cell cultures. Among them, the complex with R=4‐C6H4OMe and R'=Me emerged as the best performer of the series, being on average about six times more active against cancer cells than a noncancerous cell line, and displayed IC50 values comparable to those of cisplatin in 3D cell cultures. Mechanistic studies revealed the ability of the complexes to release carbon monoxide and to act as oxidative stress inducers in cancer cells. [ABSTRACT FROM AUTHOR]

A series of 4‐aryl‐2‐imino‐1,3‐dithiolanes was synthesized by means of a straightforward strategy starting from readily available precursors: reactions of dithiocarbamates and arylsulfonium salts, at room temperature in water/CH2Cl2 as biphasic medium, afforded the five‐membered cyclic products in good yields. The reaction mechanism was investigated by DFT calculations. [ABSTRACT FROM AUTHOR]

Mononuclear RuII complex [RuCl(κ3N‐tpm)(κ2N‐bptz)]Cl, [1]Cl [tpm=tris(1‐ pyrazolyl)methane; bptz=3,6‐di(2‐pyridyl)‐1,2,4,5‐tetrazine], and dinuclear complexes [RuCl(κ3N‐tpm)(μ‐κ2N:κ2N‐bptz)Ru(κ2N‐bipy)2][PF6]3, [3][PF6]3, [RuCl(η6‐p‐cymene)(μ‐κ2N:κ2N‐dpp)Ru(κ2N‐bipy)2][PF6]2, [4][PF6]2, and [RuCl(η6‐p‐cymene)(μ‐κ2N:κ2N‐dpp)Ru(κ2N‐biqn)2][PF6]3, [5][PF6]3 [dpp=2,3‐bis(2′‐pyridyl)‐pyrazine; bipy=2,2′‐bipyridine; biqn=2,2′‐quinoline], incorporating both potentially catalytic and photosensitive subunits, were synthesized and characterized by means of elemental analysis, mass spectrometry, and spectroscopic methods. The molecular structures of the new compounds were also investigated and compared by means of DFT calculations. The absorption spectra of all the compounds are dominated by metal‐to‐ligand charge‐transfer bands in the visible (which in most cases largely extend over the red portion of the spectrum) and ligand‐centered bands in the UV region. The oxidation behavior is based on metal‐centered RuII to RuIII oxidation processes, which in phosphate buffer solution are followed by a catalytic water oxidation wave for [1]Cl and [3][PF6]3. For these compounds, the mechanism of water oxidation is proposed to consist in water nucleophilic attack, according to chemical experiments with Ce(IV) salts, so demonstrating for the first time that the bptz ligand can be profitably used to build ruthenium(II) complexes with catalytic properties. On the contrary, no catalytic process is observed for 4 and 5, most likely due to the high positive potential for RuII oxidation induced by the presence of the p‐cymene moiety. [ABSTRACT FROM AUTHOR]

A facile route to PtII complexes doubly functionalized with bioactive molecules through a bipyridine‐type ligand is described. Initially, ligands LEE (containing two ethacrynic acid units), LEF (ethacrynic acid+flurbiprofen) and LEB (ethacrynic acid+biotin) were obtained in moderate to good yields from 2,2′‐bipyridine‐4,4′‐dicarboxylic acid. Subsequent reaction of the ligands with [PtCl2(DMSO)2] afforded complexes [PtCl2(LEE)] (2), [PtCl2(LEF)] (3) and [PtCl2(LEB)] (4) in high yields. All compounds were fully characterized by analytical and spectroscopic methods. Complexes 2–4 are highly stable in water/DMSO solution at 37 °C after 72 h, whereas progressive release of the bioactive fragments was detected in a cell culture medium. The compounds were assessed for their in vitro antiproliferative activity towards tumorigenic A2780, A2780cisR and Y79 cells and non‐tumourigenic HEK293 cells. In particular, the combination of ethacrynic acid and flurbiprofen in 3 overcomes cisplatin‐based resistance and provides strong cancer cell selectivity. Enzyme inhibition assays on human GST P1 and human COX‐2 and cross‐experiments with complex 1, analogous to 2–4 but lacking bio‐groups, revealed a clear synergy between the PtII frame and the bioactive organic components. [ABSTRACT FROM AUTHOR]

A series of diiron complexes with two cyclopentadienyls, two carbonyls, and one bridging vinyl‐aminoalkylidene as ligands, [3a–h]CF3SO3 and [4a–d]CF3SO3, was synthesized in 66–94% yields from diiron μ‐aminocarbyne precursors. The subsequent reactions with pyrrolidine led to selective fragmentation to aminoalkylidene‐ferracyclopentenone derivatives (5a–h and 6a–c) in 30–84% yields. The compounds were characterized by elemental analysis, Fourier transform infrared and NMR spectroscopy, and by single crystal X‐ray diffraction in three cases. The stability in aqueous media relevant to biological trials, the carbon monoxide release, and the catalytic activity in NADH oxidation were evaluated for selected compounds by NMR spectroscopy and gas chromatography. The in vitro antiproliferative activity of the compounds was determined towards cancer (A2780, A2780cisR) and noncancer (HEK‐293) cell lines. Moreover, the antibacterial activity was tested on Gram‐positive (vancomycin‐resistant E. faecium and methicillin‐resistant S. aureus) and Gram‐negative strains (A. baumannii and P. aeruginosa). [ABSTRACT FROM AUTHOR]

The development of sustainable synthetic routes to access valuable oxazolidinones via CO2 fixation is an active research area, and the aziridine/carbon dioxide coupling has aroused a considerable interest. This reaction features a high activation barrier and thus requires a catalytic system, and may present some other critical issues. Here, the straightforward gram‐scale synthesis of a series of 5‐aryl‐2‐oxazolidinones was developed at ambient temperature and atmospheric CO2 pressure, in the absence of any catalyst/co‐catalyst. The key to this innovative procedure consists in the direct transfer of the pre‐formed amine/CO2 adduct (carbamate) to common aziridine precursors (dimethylsulfonium salts), replacing the classical sequential addition of amine (intermediate isolation of aziridine) and then CO2. The reaction mechanism was investigated by NMR spectroscopy and DFT calculations applied to model cases. [ABSTRACT FROM AUTHOR]

The diiron µ‐vinyliminium compounds [Fe2Cp2(CO)(µ‐CO){µ‐η1:η3‐C3HC2HC1NMe(R)}]CF3SO3 (R = Me, 2a; R = Xyl = 2,6‐C6H3Me2, 2b; Cp = η5‐C5H5) reacted with grey selenium, in the presence of sodium methoxide, to give the corresponding Se‐functionalized derivatives [Fe2Cp2(CO)(µ‐CO){µ‐η1:η3‐C3HC2(Se)C1NMe(R)}], 3a–b, in ca. 50 % yields. The monoiron zwitterionic complex [FeCp(CO){SeC1(NMe2)C2HC3H}], 4, was obtained as a side‐product (31 %) of the reaction leading to 3a. The treatment of 3b with S8/NaOMe afforded the 2‐ferra‐thiophene [FeCp(CO){SC3HC2HC1NMe(Xyl)}], 5, in 49 % yield. The straightforward reactions of 3a with a two‐fold excess of dialkylacetylenedicarboxylates led to functionalized 3‐amino‐selenophenes appended to the diiron frame through a bridging allylidene ligand, [Fe2Cp2(CO)(µ‐CO){µ‐η1:η3‐C7(CO2R)C6(CO2R)C3HC2SeC5(CO2R)C4(CO2R)C1(NMe2)}] (R = Me, 6a; R = Et, 6b; R = tBu, 6c), in approximately 50 % yields. The synthesis of 6a–c is the result of two distinct modes of reactivity exhibited by the alkyne reactant in one pot, i.e. 1,3‐dipolar cycloaddition to C and Se atoms and insertion into Fe‐µ‐alkylidene. All the products were characterized by means of elemental analysis, IR and multinuclear NMR spectroscopy, and the molecular structure of 6a was elucidated by a single‐crystal X‐ray diffraction study. [ABSTRACT FROM AUTHOR]

Five‐ and six‐coordinated zinc(II) complexes, [Zn(QR)2(H2O)] (1–2) and [Zn(QR)2(L)] (3–8) {HQR = 4‐R(C=O)‐5‐pyrazolones in general, in detail HQC17, R = –(CH2)16CH3, HQCy, R = –C6H11; L = bipy, tmeda or en} have been synthesized and characterized by IR, 1H and 13C NMR, UV/Visible spectroscopy, elemental analysis, TGA and ESI mass spectrometry. The square pyramidal complex [Zn(QC17)2(H2O)] (1) has been structurally characterized, together with a trans octahedral [Zn(QCy)2(EtOH)2] (2b) species obtained by recrystallization of [Zn(QCy)2(H2O)] (2) from ethanol. Additionally, in both complexes [Zn(QCy)2(bipy)] (4) and [Zn(QC17)2(tmeda)] (5) structurally characterized by single crystal X ray diffraction, the same amount of Δ and Λ enantiomers are present, with the only difference related to the mutual disposition of the different type of the QR coordinated oxygen atoms. The cytotoxicity of the complexes [Zn(QCy)2(H2O)] (2), [Zn(QCy)2(bipy)] (4) and [Zn(QCy)2(en)] (8) has been evaluated in vitro against MCF‐7 human breast cancer cell line in a biohybrid membrane system. Results revealed that zinc complexes possess antiproliferative activity inducing apoptosis by activation of caspase‐3 and p‐JNK. [ABSTRACT FROM AUTHOR]

Two‐step functionalization of 4‐diphenylphosphino benzoic acid with biotin afforded 2‐(biotinyloxy)ethyl 4‐(diphenylphosphanyl)benzoate (LP), that was subsequently used to synthesize the Ru(II) arene complexes [RuCl2(η6‐p‐cymene)(LP)] (1), [Ru(C2O4)(η6‐p‐cymene)(LP)] (2) and [Ru(curc)(η6‐p‐cymene)(LP)]NO3 ([3]NO3), the latter incorporating curcumin (curcH) as an additional bioactive fragment. [Ru(curc)(η6‐p‐cymene)(PPh3)]NO3 ([4]NO3) was also prepared as a reference compound. Compounds 2 and [3]NO3 exhibited excellent stability in water/DMSO solution while being slowly activated in the cell culture medium over 72 hours. Together with LP, they were therefore assessed for their antiproliferative activity towards a panel of cancer cell lines, with different levels of biotin transporter expression. The apparent affinity of the compounds towards avidin varies, and their antiproliferative activity does not correlate with biotin transporter expression, although it is systematically enhanced when biotin‐free cell culture medium is used. [ABSTRACT FROM AUTHOR]

Ag(I)‐containing ethylcellulose (EC) films suitable as antbacterial packaging materials have been prepared and fully characterized. Different preparation methods, including the use of green casting solvents, are proposed. The Ag(I) acylpyrazolonato complexes, [Ag(Qpy,CF3)(L)], L=benzylimidazole (Bzim) and L=ethylimidazole (EtimH), used as active additives, display different modes of interactions with EC, depending on their structural features. A thorough investigation of the EC liquid‐crystalline lyotropic phase and its changes with the introduction of silver additives, has been conducted, revealing either the inclusion of complex molecules into the inner structure of the EC matrix or their dispersion on its surface. Moreover, the bactericidal activity of the prepared Ag(I) films seems to be related to the interaction between silver additives and the polymeric EC matrix. Indeed, the EC‐2b films show a particularly good performance even with a low silver content, with a relative bacterial killing of about 100 %. Tests for Ag(I) migration have been performed by using three food stimulants under two assay conditions. Low values of silver release are recorded, particularly at low concentration of silver content, in the case of all new prepared Ag(I) films. [ABSTRACT FROM AUTHOR]

The reaction of pyrrolidine with a series of cationic diiron cyclopentadienyl complexes containing a bridging vinyliminium ligand gives access to piano stool monoiron complexes based on a five-membered metallacycle that includes a vinyl-aminoalkylidene moiety, in moderate to high yields. The resulting metallacyclic motif (aminoalkylidene-ferracyclopentenone) is unique in organometallic chemistry and is partially preconstructed on the dinuclear frame. The monoiron products were fully characterized by elemental analysis, IR and multinuclear NMR spectroscopy, and in a number of cases by X-ray diffraction and cyclic voltammetry. They are robust in aqueous solutions and generally unreactive towards alkylating agents in organic solvents. However, a cationic derivative was prepared in high yield by methylation of a 2-pyridyl group. The cytotoxicity of both neutral and ionic complexes was assessed on cancerous (A2780 and A280cisR) and non-cancerous (HEK293) cell lines, revealing the influence of local structural modifications on the antiproliferative activity and the selectivity of the compounds. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Imidazolium compounds have determined a profound impact on chemistry, and several synthetic methods to access them are well established. Here, we report the serendipitous discovery of the unprecedented route to a zwitterionic imidazolium molecule with the two nitrogen atoms substituted with 4‐cyclohexanecarboxylic acid: to build the five‐membered ring, glyoxal plays the double role of source for C2 and, unusually, C1 units, the latter via thermal decomposition affording carbon monoxide as side‐product. Compound I1 was characterized by elemental analysis, multinuclear NMR, IR and ESI‐MS spectroscopy. [ABSTRACT FROM AUTHOR]

A sound synthetic procedure for the preparation of trans‐[PtBr(µ‐Br)(PPh3)]2 is described. The species was fully characterized and used to obtain [PtBr2(PPh3)(L)] complexes (L = DMSO, p‐toluidine, pyridine) by a bridge‐splitting reaction. All products were fully characterized by NMR spectroscopy, together with cis‐[PtBr2(PPh3)(NCCH3)], obtained as an intermediate in the synthesis of the dinuclear precursor. Cis‐[PtBr2(PPh3)(NCCH3)] was also studied by X‐ray diffraction. [ABSTRACT FROM AUTHOR]

The direct heterofunctionalization of acyclic α,β‐unsaturated aldehydes with N‐acylquinolinium ions contemplating the formation of two stereocentres is studied using dienamine catalysis. This work gives some new experimental insights on the remote stereocontrol in dienamine catalysis using unbiased aliphatic systems and large electrophiles, pointing to a (Z)‐preference of the reactive configuration of the second double bond. [ABSTRACT FROM AUTHOR]

The synthesis of dinuclear molecular complexes [Eu2(dbm)6(bipyMO)2], 1, [Tb2(dbm)6(bipyMO)2], 2, [Eu2(tta)6(bipyMO)2], 3 [Eu2(hfac)6(bipyMO)3], 4, [Tb2(hfac)6(bipyMO)3], 5 is here reported (bipyMO = 4,4′‐bipyridine N‐oxide, Hdbm = dibenzoylmethane, Htta = thenoyltrifluoroacetone, Hhfac = hexafluoroacetylacetone). The products were obtained in mild conditions and with high yields reacting anhydrous lanthanide β‐diketonates and bipyMO in 1:1 or 1.5 molar ratio in toluene. X‐ray single crystal studies on 2, 3, 4 showed that the heterotopic ligands are hypodentate, bridging the two lanthanide centres exclusively through the oxygen atom. Photoluminescence studies show bright red emissions from europium derivatives with absolute quantum yields up to 44 %. The heterotopic divergent bipyMO ligand reacts with neutral diketonato lanthanide complexes to yield dinuclear compounds [Ln2(β‐dik)6(bipyMO)n] (Ln = Eu, Tb) with a pendant nitrogen donor functionality. All the reported complexes have good emission properties with PLQY value up to 44 %. These derivatives are potentially useful as building blocks for the synthesis of heterometallic compounds. [ABSTRACT FROM AUTHOR]

The chemistry of diiron complexes has seen a recent renaissance, due to the prominent role played by the element iron in the development of sustainable synthetic processes and the cooperative effects provided by two metal centers working in concert, that is a concept amazingly exploited by Nature. Aminoalkylidyne derivatives of [Fe2Cp2(CO)4] are a convenient scaffold to grow organic fragments; in particular, the facile removal of one CO ligand opens the doors to the unconventional assembly of molecules/ions, affording unusual structural motifs. In particular, vinyliminium complexes result from carbyne–alkyne coupling and offers the opportunity for a great variety of selective derivatization pathways, including addition of nucleophiles, access to substituted ferrocenes, deprotonation and reduction processes, and trapping of small molecules. [ABSTRACT FROM AUTHOR]

Half‐sandwich organometal complexes of RuII, OsII, RhIII and IrIII with β‐diketone‐like ligands have been extensively explored as potential prodrugs in anticancer therapy in recent years. Here a minireview of this class of compounds is provided. A discussion of the basic structural features of the metal complexes is given, together with their in vitro anticancer activity. [ABSTRACT FROM AUTHOR]

Abstract: α‐Phenylcinnamic acid converts into polycyclic derivatives by interaction with high valent transition metal halides in chloroform at reflux temperature. Different products, featured by local structural differences depending on the nature of the metal halide system (i. e. WCl6, PCl5/NbF5 or PCl5/NbCl5), are easily isolable after treatment with water. In particular, WCl6 configures as an efficient multitasking agent, working as 1) chlorinator of the carboxylic acid function, 2) catalytic precursor for intra‐ and intermolecular rearrangements, and 3) catalytic precursor for Baeyer‐Villiger lactonization in water at ambient temperature, exploiting air as oxidant. The products have been purified by alumina chromatography, and identified by analytical and spectroscopic (IR, NMR) techniques, and by single crystal X‐ray diffraction in three cases. Their formation probably involves a common reaction pathway which has been rationalized by DFT calculations. [ABSTRACT FROM AUTHOR]

Abstract: Easily available and inexpensive FeIII carbamates were employed in the solvent‐free synthesis of a series of cyclic carbonates from epoxides and CO2 at room temperature and atmospheric pressure, in the presence of a cocatalyst. Different experimental conditions (type and concentration of catalyst and cocatalyst, as well as reaction time) were investigated: Fe(O2CNEt2)3 and NBu4Br acted as the best catalyst/cocatalyst combination, allowing the formation of propylene carbonate and 1,2‐butylene carbonate with quantitative yield and selectivity in 24 h. According to NMR and DFT studies, the reaction proceeds with the dynamic trapping of carbon dioxide as a carbamato ligand. [ABSTRACT FROM AUTHOR]

The RuII arene complexes [Ru(η6‐p‐cymene)(κ2N,O‐aa)Cl] (aa = l‐glutaminato, 1; l‐homoserinato, 2; l‐tyrosinato, 3; l‐serinato, 4; l‐prolinato, 5; trans‐4‐hydroxyl‐ l‐prolinato, 6; l‐threoninato, 7; glycinato, 8) were synthesized in high yields by the reactions of [Ru(η6‐p‐cymene)Cl2]2 with aa/MOH (M = Na, K). The salt [Ru(η6‐p‐cymene)(κ2N,O‐ l‐serinato)(PPh3)][CF3SO3], 9[CF3SO3], was prepared in 68 % yield from 4 and AgSO3CF3/PPh3. All the products were fully characterized by analytical and spectroscopic methods, moreover the X‐ray structures of 1 and 2 were elucidated by X‐ray diffraction. Compounds 1–7 and 9[CF3SO3] were studied as catalytic precursors for the transfer hydrogenation reaction (THR) of acetophenone, using 2‐propanol or sodium formate (in water) as hydrogen sources, under variable experimental conditions. The catalytic process was investigated also under microwave irradiation. In general, all the catalytic reactions selectively afforded 1‐phenylethanol, and the best results were achieved with 5 and 6, in terms of both activity and enantioselectivity (enantiomeric excess up to 78 %). The in vitro cytotoxicity of 1, 4, 5 and 9[CF3SO3] was assessed towards the human pancreatic cancer cell line BxPC3 and the mouse embryo fibroblast Balb/3T3 Clone A31 cell line, all of the investigated compounds showing to be substantially inactive. The catalytic and biological results will be discussed in relation to the relevant chemical behaviour of the compounds in water solution. [ABSTRACT FROM AUTHOR]

Two new platinum(II) complexes bearing triphenylphosphine and bidentate oxime ligands [Pt(Cl)(PPh3){(κ2‐N,O)‐(1{C(R)=N(OH)‐2(O)C10H6})}] (R = H, Me) were synthesized in good yields from trans‐[PtCl(µ‐Cl)(PPh3)]2. The structure of [Pt(Cl)(PPh3){(κ2‐N,O)‐(1{CH=N(OH)‐2(O)C10H6})}] was determined by single‐crystal X‐ray diffraction. Both complexes showed good antiproliferative properties in vitro against HeLa, A2780, and A2780cis cancer cell lines. They reacted cleanly with alkylating agents in the presence of aqueous bases under phase‐transfer catalysis conditions to afford the corresponding O‐alkylation products [Pt(Cl)(PPh3){(κ2‐N,O)‐(1{HC=N(OR′)‐2(O)C10H6})}] [R′ = CH2CH2Cl, CH2Ph, (CH2)4Br] in good yields. [ABSTRACT FROM AUTHOR]

The vanadium(V) amido-carbamato derivatives VO(NR2)(O2CNR2)2 (R = Me, 1; Et, 2) are obtained by the reaction of VOCl3 with preformed carbamato species (ammonium or sodium carbamates). The synthesis of an ionic ammonium chlorido-amide of WVI, 3, is performed using WOCl4 and diethylamine as precursors. Moreover, the reactivity of 3 with CO2 is investigated. Mixed WVI chlorido-carbamato compounds, 4 and 5, are obtained by the reaction of WOCl4 with stoichiometric amounts of sodium diethylcarbamate. All of the products are characterized by analytical and spectroscopic methods (IR spectroscopy, multinuclear NMR spectroscopy) and by X-ray diffraction in the cases of 3 and 4. DFT calculations are useful to elucidate the structures of the compounds and to give insight into the various reaction pathways. The combination of 2 or 5 with amorphous silica gives solid materials, which are characterized by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and energy dispersive X-ray spectroscopy (EDS) coupled to scanning electron microscopy (SEM). [ABSTRACT FROM AUTHOR]

Diiron μ-aminocarbyne compounds, 1a--e, are prepared in two steps from Fe2Cp2 (CO) 4, negating the need for difficult purification procedures of intermediate species; they are efficiently isolated by alumina chromatography. Minor amounts of μ-aminocarbyne aryl isocyanide compounds, 2a--c, are obtained as side products. The structures of the cations in 1a,c,e are calculated using DFT; the carbyne carbon is generally predicted to be the thermodynamic site of hydride addition, in agreement with a previous experimental finding concerning 1a. Accordingly, the reaction of 1e with NaBH4 affords a bridging aminocarbene complex, 4, in 85 % yield. Otherwise, the reaction of 1c with NaBH4 yields the aminocarbyne--cyclopentadiene derivative 3 (70 %), presumably as a consequence of the steric protection exerted by the xylyl--methyl groups towards the carbyne moiety. The sequential treatment of 1a,c with Li2CuCNMe2 and MeSO3CF3 affords 5a,b, comprising both aminocarbyne and alkoxycarbene ligands. In accordance with DFT calculations, the alkoxycarbene moiety in 5a is the most favourable site for nucleophilic attack. Thus, the reactions of 5a with NH2R (R = Et, iPr) and NBu4CN, respectively, give the aminocarbyne/aminocarbene complexes, 6a,b, and the aminocarbyne-α-cyanoalkyl 7. All the products are fully characterized by spectroscopic and analytical methods; moreover, the structures of 1a, 1d, 6a and 7 are elucidated by single-crystal X-ray diffraction studies. [ABSTRACT FROM AUTHOR]

We have prepared the first niobium(V) compounds bearing fluorido and monodentate amido ligands (1a-c), which are tetranuclear cations, by the reaction between NbF5 and Me3SiNMe2 in the presence of a chloride (or bromide) source. The fluorido/carbamato derivative NbF2(O2CNMe2)3 (2) was obtained in good yield from the reaction of NbF5 and Me3SiNMe2 in the presence of carbon dioxide at 1 atm pressure and ambient temperature. All the products were characterized by analytical and spectroscopic (IR, multinuclear NMR) methods, and by X-ray diffraction in the cases of 1b,c. DFT calculations were useful for elucidating the structures of the products and also for providing an insight into the reaction pathways. [ABSTRACT FROM AUTHOR]

Dicationic ruthenium(II)-p-cymene complexes containing curcumin ligands (curcH = curcumin, bdcurcH = bisdemethoxycurcumin) and ionic N-methyl-1,3,5-triaza-7-phosphaadamantane [PTA-Me]X (X = BF4 or I) have been synthesized and fully characterized for the first time. The solid-state structure of [Ru(p-cym)(curc)(PTA-Me)][SO3CF3][BF4] has also been determined by single-crystal X-ray diffraction. Modest antiproliferative activities of the complexes were observed against cisplatin-sensitive and cisplatin-resistant human ovarian carcinoma cells (A2780 and A2780cisR, respectively) and nontumorigenic human embryonic kidney (HEK293) cells. [ABSTRACT FROM AUTHOR]

The burgeoning field of metal − organic frameworks or porous coordination polymers has received increasing interest in recent years. In the last decade these microporous materials have found several applications including storage and separation of gases, sensors, catalysis and functional materials. In order to better design new metal − organic frameworks and porous coordination polymers with specific functionalities a fundamental issue is to achieve a basic understanding of the relationship between molecular parameters and structures, preferred adsorption sites and properties by using using modern theoretical methods. The focus of this mini-review is a description of the potential and emerging applications of metal − organic frameworks. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The synthesis of a series of neutral arene-ruthenium(II) complexes (arene = p-cymene, hexamethylbenzene, and benzene) [(arene)Ru(HDB)Cl] derived from the reaction of the appropriate arene-ruthenium(II) dimers and ortho-hydroxydibenzoylmethane (HDBH), a potent inhibitor of cell proliferation, is described. In addition, related ionic complexes [(arene)Ru(HDB)(PTA)](SO3CF3) (PTA = 1,3,5-triaza-7-phosphaadamantane) have been prepared. The structure of three complexes has been confirmed by X-ray crystallography. The cytotoxicity of the complexes has been evaluated against human ovarian carcinoma cells (A2780 and A2780cisR), as well as against nontumorigenic human embryonic kidney (HEK293) cells, and compared to the free ligand and cisplatin. Two of the complexes, that is from the first series with p-cymene and hexamethylbenzene, display relevant activities against the cisplatin-resistant A2780cisR cancer cell line. [ABSTRACT FROM AUTHOR]

The diiron µ-aminocarbyne imidoyl complexes [Fe2{µ-CN(Me)(R)}(µ-CO)(CO){C(C≡CR′)=NXyl}Cp2] [R = Xyl, R′ = Ph ( 1a);[1] R = Xyl, R′ = Tol ( 1b);[1] R = Me, R′ = Ph ( 1c); R = Me, R′ = SiMe3 ( 1d); Xyl = 2,6-C6H3Me2, Tol = 4-C6H4Me] have been prepared by the addition of lithium acetylides to precursors containing a terminal isocyanide ligand. The treatment of 1a- c with CF3SO3CH3 afforded the alkynyl(amino)carbene derivatives [Fe2{µ-CN(Me)(R)}(µ-CO)(CO){C(C≡CR′)N(Me)(Xyl)}Cp2][SO3CF3] [R = Me, R′ = Ph ( 2a); R = Xyl, R′ = Ph ( 2b); R = Xyl, R′ = Tol ( 2c)] in high yields. The reactions of 2b, c with CH3OH/NaBF4, NH2R and NaBH4 led to [Fe2{µ-CN(Me)(Xyl)}(µ-CO)(CO){C(CH=C(Ph)OMe)N(Me)(Xyl)}Cp2][BF4] ( 3), [Fe2{µ-CN(Me)(Xyl)}(µ-CO)(CO){C(CH=C(Tol)NHR)N(Me)(Xyl)}Cp2][SO3CF3] [R = Et ( 4a); R = Ph ( 4b)], and [Fe2{µ-CN(Me)(Xyl)}(µ-CO)(CO){C(CH=CHTol)N(Me)(Xyl)}Cp2][SO3CF3] ( 5) in yields of 65-80 %. Complexes 3- 5 were formed by the selective functionalization of the alkynyl group in 2b, c. Complex 2c reacted with NaCH(CN)2/CH2(CN)2 and NaCH(CO2Me)2 to yield [Fe2{µ-CN(Me)(Xyl)}(µ-CO)(CO){C{N(Me)(Xyl)}CH=C(Tol)C(CN)C(NH2)C(CN)2}Cp2] ( 6) and [Fe2{µ-C(NXyl)C(C(Tol)=C(CO2Me)2)CN(Me)(Xyl)}(µ-CO)2Cp2] ( 7) in yields of 65 and 60 %, respectively. All the products were purified by alumina chromatography, alumina being presumably involved in the formation of 3, and characterized by elemental analysis and IR and NMR spectroscopy. The structures of 2b, 3, 5, and 6 were ascertained by single-crystal X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

The reactions between MoCl5 and 1-2 equiv. of a selection of sulfoxides at room temperature in dichloromethane as solvent were studied. The 1:1 molar reaction between MoCl5 and dimethyl sulfoxide (DMSO) afforded the C-S coupling product [Me2SCH2SMe][MoOCl4] ( 1), which was isolated in 46 % yield and characterized by analytical and spectroscopic methods and by X-ray diffraction. MoOCl3, SMe2 and HCl were identified as side products. The reactions between MoCl5 and tetrahydrothiophene 1-oxide, nBu2SO, MePhSO or (PhCH2)2SO yielded the corresponding sulfides and, in the cases of (PhCH2)2SO and MePhSO, also C-S activation compounds. According to DFT calculations, the unusual formation of 1 is the consequence of thermodynamically feasible Cl/O interchange between MoCl5 and DMSO, this being a prerequisite for successive C-H bond activation. [ABSTRACT FROM AUTHOR]

The reactions of [WCl6] with a series of ethers have been performed in chlorinated solvent and elucidated by means of analytical, spectroscopic and DFT methods. The addition of tetrahydropyran (thp) or 1,4-dioxane to [WCl6] resulted in the reversible formation of the adducts WCl6... [L = thp (1a), 1,4-dioxane (1b)], detected in solution by NMR spectroscopy. The reaction of [WCl6] with thp in a molar ratio of 1:2 in chloroform at reflux afforded [WOCl4(thp)] (2a), which was isolated in 51% yield. [WOCl4(OMe2)] (2b) and [WOCl3(OMe2)2](3a) were isolated in yields of 53 and 18 %, respectively, from the reaction of [WCl6] with an excess of dimethyl ether. [WOCl3(OEt2)2](3b) was the only identified metal compound produced from the reaction of [WCl6] and OEt2 (1:2 molar ratio). According to NMR studies, the oxide ligand in 2a,b and 3a,b was generated by double C-O bond cleavage involving one equivalent of organic reactant. The 1:1 reaction of [WCl6] with 1,2-diethoxyethane led to [WCl5(κ²-OCH2CH2OEt)] (4) and a minor amount of [WCl4(κ² EtOCH2CH2OEt)] (5). The aryl oxide compound [WCl5(OPh)] (6) was prepared in 62 % yield from the reaction of [WCl6] and anisole by selective Csp3--O bond activation. The prolonged heating of a mixture of [WCl6] and diphenyl ether in 1,2-dichloroethane led to the isolation of the WV complex [WCl5(OPh2)] (7). The molecular structures of 2a and 3a were ascertained by X-ray diffraction. [ABSTRACT FROM AUTHOR]

New silver(I) acylpyrazolonato derivatives displaying a mononuclear, polynuclear, or ionic nature, as a function of the ancillary azole ligands used in the synthesis, have been fully characterized by thermal analysis, solution NMR spectroscopy, solid-state IR and NMR spectroscopies, and X-ray diffraction techniques. These derivatives have been embedded in polyethylene (PE) matrix, and the antimicrobial activity of the composite materials has been tested against three bacterial strains ( E. coli, P. aeruginosa, and S. aureus): Most of the composites show antimicrobial action comparable to PE embedded with AgNO3. Tests by contact and release tests for specific migration of silver from PE composites clearly indicate that, at least in the case of the PE, for composites containing polynuclear silver(I) additives, the antimicrobial action is exerted by contact, without release of silver ions. Moreover, PE composites can be re-used several times, displaying the same antimicrobial activity. Membrane permeabilization studies and induced reactive oxygen species (ROS) generation tests confirm the disorganization of bacterial cell membranes. The cytotoxic effect, evaluated in CD34+ cells by MTT (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazoliumbromide) and CFU (colony forming units) assays, indicates that the PE composites do not induce cytotoxicity in human cells. Studies of ecotoxicity, based on the test of Daphnia magna, confirm tolerability of the PE composites by higher organisms and exclude the release of Ag+ ions in sufficient amounts to affect water environment. [ABSTRACT FROM AUTHOR]

Copper(I) thiocyanate derivatives were prepared by the reaction of CuNCS with pyridine (py) and tertiary monophosphine ligands [PR3 in general; in detail: PPh3, triphenylphosphine, P(4-FPh)3, tris(4-fluorophenyl)phosphine)], as well as the potentially bidentate ligand diphenyl(2-pyridyl)phosphine (PPh2py). Mechanochemical methods were used in some cases to investigate stoichieometries that were not easily accessible by conventional solution syntheses. Three forms of the resulting adducts of CuNCS/PR3/py-base (1:3- n: n) stoichiometry-all containing four-coordinate copper(I) atoms and monodentate N-thiocyanate groups-were confirmed crystallographically. Mononuclear arrays are defined for [(PPh2py)3- n(py) nCu NCS], n = 0, 1, 2, the monodentate thiocyanate being N-coordinated in all; two polymorphs are observed for the n = 2 complex, both crystallizing in monoclinic P21 ( Z = 2) cells with similar cell dimensions, but with aromatic components eclipsed about the Cu-P bond in the PPh3 complex, and staggered in the PPh2py complex. Bridging thiocyanate groups are found in the 1:1:1 CuNCS/PPh2py/2-methylpyridine (mpy) and P(4-FPh)3/mpy complexes, wherein centrosymmetric dimers with eight-membered central rings are obtained: [(R3P)(mpy)Cu( NC S)2Cu(PR3)(mpy)], as is also the case in the parent 1:2 CuNCS/PPh2py adduct [(pyPh2P)2Cu( NC S)2Cu(PPh2py)2]. For the 1:1:1 Cu NC S/P(4-FPh)3/py and PPh3/Brmpy (Brmpy = 3-bromo-4-methylpyridine) adducts, and, likely, Cu NC S/PPh2py/py (1:1:1), single-stranded polymers of the form [ ···Cu( NC S)(PR3)(py-base)(Cu) ···](∞|∞) with linearly bridging NCS ligands were obtained. Some derivatives, representative of all forms, display medium to strong green to blue luminescence when excited with radiation at 365 nm. The 31P CPMAS NMR spectroscopic data clearly differentiate the inequivalent phosphorus positions within each system, showing a wide range of 1 J(31P,63/65Cu) values ranging from 965 Hz for [Cu( NCS)(PPh2py)3] to 1540 Hz for dimeric [(4-FPh)3P(mpy)Cu( NC S)2Cu(P(4-FPh)3)(mpy)], reflecting the large variations in the Cu-P bond length. [ABSTRACT FROM AUTHOR]

[RuCl(arene)(μ-Cl)]2 dimers were treated in a 1:2 molar ratio with sodium or thallium salts of bis- and tris(pyrazolyl)borate ligands [Na(Bp [ABSTRACT FROM AUTHOR]

The syntheses of new PtII complexes with 4-acyl-5-pyrazolones [HQPh = 1-phenyl-3-methyl-4-benzoylpyrazol-5-one, a; HQpy,CF3 = 1-(2-pyridyl)-3-methyl-trifluoroacetylpyrazol-5-one, b] are reported: trans-[PtCl2(DMSO)(HQPh)] ( 1a), cis-[PtCl2(DMSO)(HQPh)] ( 2a), [PtCl(DMSO)(Qpy,CF3)] ( 1b), and [PtCl2(KQpy,CF3)] ( 2b). All complexes were characterized by multinuclear (1H, 13C, 19F, and 195Pt), multidimensional NMR spectroscopy and single-crystal X-ray diffraction analyses. The isomer trans-[PtCl2(DMSO)(HQPh)] ( 1a) crystallizes in two polymorphic forms, which correspond to two different conformers. In the trans- syn conformer ( 1aM) (monoclinic, space group P21/ c), the H atom of the enol group [O(1)H(1)] establishes an intramolecular hydrogen bond with the ketone oxygen (O2), whereas in the trans- anti conformer ( 1aO) (orthorhombic, space group Pca21), the same groups are involved in an analogous intermolecular H bond. Interestingly, the cis isomer ( 2a) showed in solution and at room temperature slow rotation around both the Pt-N1 and the Pt-S bonds, which restrained both the acylpyrazolone and DMSO ligand motion. Moreover, the water solubility of the complexes trans- and cis-[PtCl2(DMSO)(HQPh)] ( 1a and 2a) and [PtCl2(KQpy,CF3)] ( 2b) allowed to perform in vitro biological assays on platinum-sensitive human endometrium (HeLa) and platinum-resistant human breast (MCF-7) cancer cell lines. It was also possible to compare their cytotoxicity to cisplatin. Interestingly, trans isomer 1a showed higher cytotoxicity on HeLa cells compared to the cis isomer 2a. [ABSTRACT FROM AUTHOR]

Six scorpionate complexes of group 10-12 metal elements (CuI, CuII, ZnII, and CdII) containing the anionic hydrotris[3-(2′-thienyl)pyrazol-1-yl]borate (TpTn) ligand were prepared from the reaction of the thallium(I) salt of TpTn with the corresponding metal acceptors in chloroform solution. The air- and heat-stable complexes were characterized by analytical and spectroscopic methods (IR, conductivity, ESI-MS, 1H NMR and 13C NMR solution data) and structurally characterized by single-crystal X-ray studies. The ZnII complexes [Zn(TpTn)X] (X = Cl or Br) contain a tripodal tridentate TpTn ligand, in which the tetrahedral metal environment is completed by a halide; in [Cd(TpTn)2], cadmium is found in an octahedral environment coordinated by two TpTn ligands. In [Cu(TpTn)(PPh3)] ·CHCl3 and [Cu(TpTn)(OC(O)CH3)], TpTn is also coordinated in the tripodal fashion, in which the copper environment is completed by a triphenylphosphine ligand in the former complex and by a symmetrically coordinated bidentate acetate ligand occupying trans-coordinated sites in the latter complex. The reaction of [Zn(TpTn)X] with an excess amount of [Tl(TpTn)] in MeOH yielded [Zn(TpTn)2] and TlX, whereas the reaction of [Zn(TpTn)X] with Na(Tp) gave [Zn(TpTn)2] and [Zn(Tp)2] in a 1:1 molar ratio but not [Zn(TpTn)(Tp)]. By contrast, the reaction of [Tl(TpTn)] with copper(II) sulfate monohydrate in chloroform gave a green powder, which was identified as the [(Hpz3Tn)4CuSO4](∞|∞) coordination polymer containing OSO2 O bridging sulfate groups and four coordinated pyrazole ligands on each metal center, the latter of which arises from the decomposition of the TpTn ligand through B-N bond breaking. Similarly, the interaction between [Tl(TpTn)] and platinum(II) diiodide in chloroform/DMSO proceeded through TpTn decomposition to afford a monomeric trans-[(Hpz3Tn)2PtI2] ·2(CH3)2SO complex, wherein two neutral pyrazole ligands are coordinated to the PtII center. [ABSTRACT FROM AUTHOR]

The 3:1 molar reactions of MF5 (M = Nb, 1a; M = Ta, 1b) with 1,3-dimethoxybenzene in CHCl3 led to the formation of the arenium salts [2,4-(OMe)2C6H5][M2F11] (M = Nb, 3a; M = Ta, 3b) in good yields. The reactions took place with the intermediate formation of (MF5)2[κ2-1,3-(OMe)2C6H4] (M = Nb, 2a; M = Ta, 2b), followed by single-electron oxidation of the arene and production of MF4 (identified by means of EPR spectroscopy as the acetonitrile adduct). Compounds 3a and b were fully characterised both in solution (NMR) and in the solid-state (X-ray, IR and elemental analysis), while 2a and b were identified by NMR spectroscopy in CD2Cl2 solution. The reactions of 1,3-dimethoxybenzene with Ag[NbF6] or Ag[Sb2F11] in CD2Cl2/CHCl3 afforded [2,4-(OMe)2C6H5]+. It was found that 1,3-dimethoxybenzene was inert towards the addition of aqueous H[SbF6] under comparable experimental conditions. [ABSTRACT FROM AUTHOR]

The vinyliminium complexes [Fe2{μ-η1:η3-C(R)C(R)CN(Me)2}(μ-CO)(CO)(Cp)2][SO3CF3] (R = Me, 3a; R = CO2Me, 3b; R = Ph, 3c) were treated with S8 in the presence of tBuLi, undergoing fragmentation and affording the corresponding six-membered metallacyclic complexes [Fe(Cp)(CO){SC(R)=C(R)C(NMe2)S}] ( 5a- c). Complexes 5a- c result from cleavage of the diiron precursor and addition of S to the vinyliminium ligand to generate a dithiochelating ligand. Analogous reactions of the vinyliminium complexes [Fe2{μ-η1:η3-C(R)C(R)CN(Me)(Xyl)}(μ-CO)(CO)(Cp)2][SO3CF3] (R = Me, 3d; R = CO2Me, 3e), which contain a Xyl group (Xyl = 2,6-Me2C6H3) in place of a methyl, displayed a different outcome. Complex 3d afforded the diiron complex [Fe2{μ-η1:η3-C(Me)=C(CS2)C=N(Me)(Xyl)}(μ-CO)(CO)(Cp)2] ( 10), whereas 3e led to the formation of the five-membered metallacycle [Fe(Cp)(CO){C{N(Me)(Xyl)}C(CO2Me)C(CO2Me)S}] ( 11) together with the diiron complex [Fe2{μ-η1:η3-C(CO2Me)=C(S)C=N(Me)(Xyl)}(μ-CO)(CO)(Cp)2] ( 12). The formation of 10 and 12 implies C-H and C-C cleavage, respectively, and C-S bond formation without rupture of the diiron framework. The vinyliminium complexes 3a- d and also [Fe2{μ-η1:η3-C(Et)C(Et)CN(Me)(CH2Ph)}(μ-CO)(CO)(Cp)2][SO3CF3] ( 3f) reacted with gray selenium in the presence of tBuLi to afford the five-membered metallacycles [Fe(Cp)(CO){C{N(Me)R}C(R′)C(R′)Se}] (R = R′ = Me, 13a; R = Me, R′ = CO2Me, 13b; R = Me, R′ = Ph, 13c; R = Xyl, R′ = Me, 13d; R = CH2Ph, R′ = Et, 13f) in which one Se atom has been incorporated into the chelating ligand. The X-ray molecular structures of 5a and 13a have been determined. [ABSTRACT FROM AUTHOR]

The 1:3 reactions of the alkoxy arenes 1,4-(MeO)2C6H4 and 1,4-F2-2,5-(MeO)2C6H2 with TaF5 in chloroform at 40-50 °C resulted in formation in about 35 % yield of the long-lived radical cation salts [1,4-(MeO)2C6H4][Ta2F11] ( 2 a) and [1,4-F2-2,5-(MeO)2C6H2][Ta2F11] ( 2 b), respectively. The non-alkoxy-substituted [arene][M2X11] [M=Ta, X=F: arene=C6H5Me ( 2 c), 1,4-C6H4Me2 ( 2 d), C6H5F ( 2 e), C6H5NO2 ( 2 f); M=Nb, X=F: arene=C6H5Me ( 4 a), 1,4-C6H4Me2 ( 4 b), C6H5F ( 4 c), C6H5NO2 ( 4 d); M=Ta, X=Cl: arene=1,4-C6H4Me2 ( 5)] were obtained from the 3:1 reactions of MX5 with the appropriate arene in chloroform at temperatures in the range 40-90 °C. Compounds 2- 5 were detected by EPR spectroscopy (in CHCl3) at room temperature, and their gas-phase structures were optimized by DFT calculations. Formation of the MIV species [MX4(NCMe)2] [M=Ta, X=F ( 3 a); M=Nb, X=F ( 3 b); M=Ta, X=Cl ( 3 c)] was ascertained by EPR spectroscopy on solutions obtained by treatment of the reaction mixtures with acetonitrile. Non-selective reactions occurred upon combination of 1,4-F2-2,5-(MeO)2C6H2 with AgNbF6 (in CH2Cl2) and 1,4-(MeO)2C6H4 with SbF5. [ABSTRACT FROM AUTHOR]

The complexes [Mo(O)2(QR)2] [R = cyclohexyl ( 1), ethylcyclopentyl ( 2), hexyl ( 3), and neopentyl ( 4)] have been obtained in good yields by treatment of [Mo(O)2(acac)2] with 2 equivalents of acylpyrazolone compounds HQR [HQR = 3-methyl-1-phenyl-4-alkylcarbonyl-5-pyrazolone; R = cyclohexyl (HQCy), ethylcyclopentyl (HQEtCp), hexyl (HQHe), neopentyl (HQ nPe)]. They were isolated as yellow crystalline solids and characterized spectroscopically [IR, 1H and 13C(1H) NMR] and structurally (X-ray for 2 and 3). The deoxygenation of selected epoxide substrates to alkenes by employing compounds 1 and 3 as catalysts and PPh3 as the oxygen acceptor showed good activities in toluene. The use of the ionic liquid [C4mim]PF6 as solvent gave lower yields, but the resulting catalytic system could be conveniently recycled. The [Mo(O)2(QR)2] derivatives 1 and 3 were also found to be moderately active catalysts for the deoxydehydration of vicinal diols. [ABSTRACT FROM AUTHOR]

N, N-Diethylcarbamates [NbE(O2CNEt2)3] (E = O, S) have been prepared in high yields by treating NbOCl3 or [NbSCl3(CH3CN)2] with CO2/NHEt2 in toluene at approximately -10 °C. The products were characterized by spectroscopic techniques, elemental analysis and X-ray diffractometry in the case of [NbO(O2CNEt2)3]. The molecular structure of the latter consists of a niobium centre coordinated to the oxido moiety and six O atoms belonging to bridging and bidentate carbamates, in a slightly distorted pentagonal-bipyramidal arrangement. The structures of both [NbE(O2CNEt2)3] compounds were reproduced by DFT calculations, which show substantial similarity despite the different nature of the chalcogen atoms. [ABSTRACT FROM AUTHOR]