Characterization and Thermal Activation of Adducts of Group 4 Tetrahalides with 1,2-Dialkoxyalkanes

Coordination compounds of general formula MX4[κ2-O(R)CH2CH(R′)OR′′], 2a–i, have been prepared in high yield upon addition of a variety of 1,2-dialkoxyalkanes, ROCH2CH(R′)OR′′, to MX4 (M = Ti, X = F, 1a, I, 1b; M = Zr, X = Br, 1c, I, 1d). The new complexes have been characterized by elemental analysis and NMR spectroscopy. The thermal stability of 2 has been studied. Fragmentation of the TiI4 adducts takes place in chloroform solution at 90 °C: after hydrolysis of the reaction mixtures, MeI and CH2ICH2I have been detected from TiI4[dme] [dme = MeO(CH2)2OMe], MeI and Me2O from TiI4[MeOCH2CH(Me)OMe], and MeI, CH2ICH2I, Me2O, CH2ClI from TiI4[MeO(CH2)2OCH2Cl]. The diether MeO(CH2)2OCH2Cl is thermally activated also when coordinated to ZrX4 (X = Br, I): after hydrolysis, MeBr, CH2BrCH2Br, O(CH2CH2Cl)2 and Me2O (X = Br) and MeI, CH2ClI and CH2ICH2I (X = I) have been found, respectively

Recent advances in the chemistry of metal carbamates

Following a related review dating back to 2003, the present review discusses in detail the various synthetic, structural and reactivity aspects of metal species containing one or more carbamato ligands, representing a large family of compounds across all the periodic table. A preliminary overview is provided on the reactivity of carbon dioxide with amines, and emphasis is given to recent findings concerning applications in various fields

Halo-complexes of Titanium(III): the Thermochromic Behaviour of [NBu4][TiCl4(thf)2]

TiCl3(thf)3 reacts with ACl (A = NBu4, PPN; PPN = Ph3PNPPh3) in dichloromethane solution, affording the compounds A[TiCl4(thf)2] (A = NBu4, 1; A = PPN, 2). Compound 1, dissolved in CH2Cl2, exhibits thermochromic behaviour which has been the subject of variable-temperature UV–Vis investigations

Non-precious metal carbamates as catalysts for the aziridine/CO2coupling reaction under mild conditions

The catalytic potential of a large series of easily available metal carbamates (based on thirteen different non-precious metal elements) was explored for the first time in the coupling reaction between 2-aryl-aziridines and carbon dioxide, working under solventless and ambient conditions and using tetraalkylammonium halides as co-catalysts. The straightforward synthesis of novel [NbCl3(O2CNEt2)2],NbCl, and [NbBr3(O2CNEt2)2],NbBr, is reported. The niobium complexNbCl, in combination with NBu4I, emerged as the best catalyst of the overall series to convert aziridines with smallN-alkyl substituents into the corresponding 5-aryl-oxazolidin-2-ones

The cytotoxic activity of diiron bis-cyclopentadienyl complexes with bridging c3-ligands

Diiron bis-cyclopentadienyl bis-carbonyl cationic complexes with a bridging vinylim-inium ligand, [Fe2Cp2 (CO)(µ-CO){µ-η1:η3-C3 (R′)C2HC1NMe(R′′)}]CF3SO3 (R = Xyl = 2,6-C6H3Me2, R′ = Ph, R′′ = H, 2a; R = Xyl, R′ = R′′ = Me, 2b; R = R′ = Me, R′′ = H, 2c; R = Me, R′ = 2-naphthyl, R′′ = H, 2d; R = Me, R′ = R′′ = Ph, 2e), are easily available from commercial chemicals, robust in aqueous media and exert a variable in vitro cytotoxicity against cancer cell lines depending on the nature of the substituents on the vinyliminium ligand. The anticancer activity is, at least in part, associated to fragmentation reactions, leading to iron oxidation and active neutral and well-defined monoiron species. We report an innovative synthetic procedure for the preparation of 2a,c,d, and a facile method to access the monoiron derivative of 2a, i.e., [FeCp(CO){C1 (NMeXyl)C2HC3 (Ph)C(O)}] (3a). According to IC50 analyses at different times of incubation of the complexes, 3a is significantly faster in inhibiting cell viability compared to its diiron precursor 2a. The neutral complexes [Fe2Cp2 (CO)(µ-CO){µ-k1N:k1C:k1C-C3 (R′)C2 (Se)C1 (NMe2)C4 (CO2Y)C5 (CO2Y)}] (R′ = Y = Me, 4a; R′ = Pr, Y =tBu, 4b; R′ = Y = Et, 4c) are obtained via the two-step modification of the vinyliminium moiety and comprise a bridging selenophene-decorated alkylidene ligand. The antiproliferative activity exhibited by 4a-c is moderate but comparable on the ovarian cancer cell line A2780 and the corresponding cisplatin resistant cell line, A2780cisR. Complexes 4a-c in aqueous solutions undergo progressive release of the alkylidene ligand as a functionalized selenophene, this process being slower in cell culture medium. Since the released selenophenes SeC1 {C(O)R′ }C2 (NMe2)C3 (CO2Y)C4 (CO2Y) (R′ = Y = Me, 5a; R′ = Pr, Y =tBu, 5b) are substantially not cytotoxic, it is presumable that the activity of 4a-c is largely ascribable to the {Fe2Cp2 (CO)2 } scaffold

Synthesis of α-alkylidene cyclic carbonatesviaCO2fixation under ambient conditions promoted by an easily available silver carbamate

The simple and cost-effective compound [Ag(O2CNEt2)], in combination with PPh3, works as an effective catalytic precursor in the carboxylation of propargyl alcohols at ambient temperature and atmospheric CO2pressure, and in most cases under solventless conditions. The silver carbamate revealed a better performance than commercial silver oxide, Ag2O, and allowed to obtain a series of α-alkylidene cyclic carbonates in high yields

Bypassing the Inertness of Aziridine/CO2 Systems to Access 5-Aryl-2-Oxazolidinones: Catalyst-Free Synthesis Under Ambient Conditions

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

Sculpting neurotransmission during synaptic development by 2D nanostructured interfaces

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Synthesis, variable temperature NMR investigations and solid state characterisation of novel octafluorofluorene compounds

The preparation of a number of new 9-substituted octafluorofluorene derivatives, solution NMR studies, and the first examples of solid state structures of octafluorofluorenes [1,2,3,4,5,6,7,8-octafluorofluorene, C13H2F8, 1; 1,2,3,4,5,6,7,8-octafluoro-9-(pentafluoro)phenylfluorene, C19HF13, 8; 1,1′,2,2′,3,3′,4,4′,5,5′,6,6′,7,7′,8,8′-hexadecafluoro-9,9′-bifluorenyl, C26H2F16, 11] are reported. Variable temperature 19F NMR investigations have been performed on the 9-aryl substituted compounds 1,2,3,4,5,6,7,8-octafluoro-9-(pentafluoro)phenyl-9-hydroxyfluorene, C19HF13O, 4, 1,2,3,4,5,6,7,8-octafluoro-9-(nonafluoro-4′-biphenylyl)-9-hydroxyfluorene, C25HF17O, 5, and 8, and the energetic barriers to rotation of the aryl have been determined. A lower rotational barrier is observed for compound 4 with respect to compound 8, while 5 does not show fluxional behaviour below 338 K. The results of the variable temperature experiments performed on 8 have been rationalized by 2D NMR studies, and compared to the solid state data resulting from the X-ray structural analysis