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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]

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]

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]

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 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]

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]

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 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]