- Novel primary amide-based cationic metal complexes: Green synthesis, crystal structures, Hirshfeld surface analysis and solvent-free cyanosilylation reaction
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A new symmetrical and flexible primary amide functionalized ligand, 2,2′-(ethane-1,2-diylbis((pyridin-2-ylmethyl)azanediyl))diacetamide (2-BPEG), has been synthesized and structurally characterized. Using this multidentate ligand, four novel metal complex
- Markad, Datta,Mandal, Sanjay K.,Khullar, Sadhika
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- Imidazolidine Ring Cleavage upon Complexation with First-Row Transition Metals
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The reaction of a cyclic diaminal ligand, obtained from the reaction of N,N′-bis(2-pyridylmethyl)ethane-1,2-diamine, as a secondary diamine, and isophthalaldehyde, with different first-row transition-metal ions, such as FeIII, ZnII,
- Cheaib, Khaled,Herrero, Christian,Guillot, Régis,Banse, Frédéric,Mahy, Jean-Pierre,Avenier, Frédéric
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- Competitive 7Li NMR Study on the Mn2+, Zn2+ and Cd2+ Complexes of Two New Branched Hexadentate (N6) Amines Containing the Pyridine Moiety in Nitromethane and Acetonitrile Solutions
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Lithium-7 NMR spectroscopy was used to investigate the stoichiometry and stability of a Li+ complex with two new branched amines, 4,7-bis(2-pyridylmethyl)-4,7-diazadecane-1,10-diamine (L1) and 4,8-bis(2-pyridylmethyl)-4,8-diazaundecane-1,11-diamine (L2), in acetonitrile and nitromethane. A competitive 7Li NMR method was also employed to probe the complexation of Mn2+, Zn2+ and Cd2+ ions with L1 and L2 in the same solvent systems. The formation constants of the resulting complexes were evaluated from computer fitting of the mole ratio data with an equation that relates the observed chemical shifts to the formation constant. In both solvents, the stability of the resulting 1:1 complexes was found to vary in the order Cd2+ > Zn2+ > Mn2+ > Li+.
- Keypour, Hassan,Zebarjadian, Mohammad Hasan,Rezaeivala, Majid,Shamsipur, Mojtaba,Bijanzadeh, Hamid Reza
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- Nitric oxide reactivity of Cu(ii) complexes of tetra- and pentadentate ligands: Structural influence in deciding the reduction pathway
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Four Cu(ii) complexes, 1, 2, 3 and 4, are synthesized with ligands, L 1, L2, L3 and L4 [L1 = N1,N2-bis((pyridin-2-yl)methyl)ethane-1,2-diamine; L2 = N1,N3-bis((pyridin-2-yl)methyl)propane-1,3-diamine; L3 = N1,N1,N2-tris((pyridin-2-yl)methyl)ethane-1,2-diamine; L4 = N1-((1-methyl-1H-imidazol-2-yl)methyl)-N1,N2-bis((pyridin-2-yl)methyl)ethane-1, 2-diamine], respectively, as their perchlorate salts. The complexes were characterized by various spectroscopic techniques as well as single crystal X-ray structure determination. Nitric oxide reactivities of the complexes were studied in acetonitrile as well as methanol solvent. It has been found that the ligand frameworks have a considerable effect in controlling the mechanism of the reduction of a Cu(ii) center by nitric oxide. The flexibility of the ligand/s for a Cu(ii) complex to attain a trigonal bipyramidal geometry after NO coordination is found to be the most important parameter in dictating the pathway for their interaction. In the present study, all the four compounds, because of structural constraints, were found to follow a deprotonation pathway for the reduction of a Cu(ii) center by nitric oxide rather than [Cu II-NO] intermediate formation. All the ligands were found to yield an N-nitrosoamine product along with the reduction of Cu(ii) centers by nitric oxide.
- Kumar, Pankaj,Kalita, Apurba,Mondal, Biplab
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- Polypyridine ligands as potential metallo-β-lactamase inhibitors
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Bacteria have developed multiple resistance mechanisms against the most used antibiotics. In particular, zinc-dependent metallo-β-lactamase producing bacteria are a growing threat, and therapeutic options are limited. Zinc chelators have recently been investigated as metallo-β-lactamase inhibitors, as they are often able to restore carbapenem susceptibility. We synthesized polypyridyl ligands, N,N′-bis(2-pyridylmethyl)-ethylenediamine, N,N,N′-tris(2-pyridylmethyl)-ethylenediamine, N,N′-bis(2-pyridylmethyl)-ethylenediamine-N-acetic acid (N,N,N′-tris(2-pyridylmethyl)-ethylenediamine-N′-acetic acid, which can form zinc(II) complexes. We tested their ability to restore the antibiotic activity of meropenem against three clinical strains isolated from blood and metallo-β-lactamase producers (Klebsiella pneumoniae, Enterobacter cloacae, and Stenotrophomonas maltophilia). We functionalized N,N,N′-tris(2-pyridylmethyl)-ethylenediamine with D-alanyl-D-alanyl-D-alanine methyl ester with the aim to increase bacterial uptake. We observed synergistic activity of four polypyridyl ligands with meropenem against all tested isolates, while the combination N,N′-bis(2-pyridylmethyl)-ethylenediamine and meropenem was synergistic only against New Delhi and Verona integron-encoded metallo-β-lactamase-producing bacteria. All synergistic interactions restored the antimicrobial activity of meropenem, providing a significant decrease of minimal inhibitory concentration value (by 8- to 128-fold). We also studied toxicity of the ligands in two normal peripheral blood lymphocytes.
- La Piana, Luana,Viaggi, Valentina,Principe, Luigi,Di Bella, Stefano,Luzzaro, Francesco,Viale, Maurizio,Bertola, Nadia,Vecchio, Graziella
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- Photomagnetism of a sym-cis-dithiocyanato iron(II) complex with a tetradentate N,N'-bis(2-pyridylmethyl)1,2-ethanediamine ligand
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A comprehensive study of the magnetic and photomagnetic behaviors of cis-[Fe(picen)(NCS)2] (picen=N,N'-bis(2-pyridylmethyl)1,2- ethanediamine) was carried out. The spin-equilibration was extremely slow in the vicinity of the thermal spin-transition. When the cooling speed was slower than 0.1 K min-1, this complex was characterized by an abrupt thermal spin-transition at about 70 K. Measurement of the kinetics in the range 60-70 K was performed to approach the quasi-static hysteresis loop. At low temperatures, the metastable HS state was quenched by a rapid freezing process and the critical T(TIESST) temperature, which was associated with the thermally induced excited spin-state-trapping (TIESST) effect, was measured. At 10 K, this complex also exhibited the well-known light-induced excited spin-state-trapping (LIESST) effect and the T(LIESST) temperature was determined. The kinetics of the metastable HS states, which were generated from the freezing effect and from the light-induced excitation, was studied. Single-crystal X-ray diffraction as a function of speed-cooling and light conditions at 30 K revealed the mechanism of the spin-crossover in this complex as well as some direct relationships between its structural properties and its spin state. This spin-crossover (SCO) material represents a fascinating example in which the metastability of the HS state is in close vicinity to the thermal spin-transition region. Moreover, it is a beautiful example of a complex in which the metastable HS states can be generated, and then compared, either by the freezing effect or by the LIESST effect. Copyright
- Letard, Jean-Francois,Asthana, Saket,Shepherd, Helena J.,Guionneau, Philippe,Goeta, Andre E.,Suemura, Naohiko,Ishikawa, Ryuta,Kaizaki, Sumio
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- Electrochemical Exploration of Active Cu-Based Atom Transfer Radical Polymerization Catalysis through Ligand Modification
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The intersection between Cu-catalyzed atom transfer radical polymerization (ATRP) and organometallic mediated radical polymerization (OMRP) has been recently shown to be a result of competition between the CuI and CuII complexes of polyamine ligands for the same organic free radical. The tetradentate ligands N,N′-bis-2′-pyridylmethyl-ethane-1,2-diamine (L1) and N,N′-dimethyl-N,N′-bis-2′-pyridylmethyl-ethane-1,2-diamine (L2) form stable Cu complexes which, depending on their oxidation state, can either liberate or complex organic radicals. Herein, we show that this process may be affected by subtle changes to the ligand system. Switching from a tertiary amine (L2) to a secondary amine (L1) retains ATRP and OMRP activity through a series of cyclic voltammetry measurements in the presence of the initiator bromoacetonitrile.
- Bernhardt, Paul V.,Melville, Jamie N.
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p. 9709 - 9719
(2021/07/19)
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- In Situ Ligand Formation in the Synthetic Processes from Mononuclear Dy(III) Compounds to Binuclear Dy(III) Compounds: Synthesis, Structure, Magnetic Behavior, and Theoretical Analysis
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Guided by the self-assembled process and mechanism, the strategy of in situ Schiff base reaction would be capable of bringing a feasible method to construct and synthesize lanthanide compounds with distinct structures and magnetic properties. A mononuclea
- Zhang, Sheng,Tang, Jiamin,Zhang, Jin,Xu, Fang,Chen, Sanping,Hu, Dengwei,Yin, Bing,Zhang, Jiangwei
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supporting information
p. 816 - 830
(2021/02/03)
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- Synthesis of three new branched octadentate (N8) Schiff Base and competitive Lithium-7 NMR study of the stoichiometry and stability constant of Mn2+, Zn2+ and Cd2+ complexes in acetonitrile – [(BMIM)(PF6)] mixture
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Three new branched hexadentate amines, have been synthesized. Condensation with picolinaldehyde in methanol leads to produce three new Schiff base, with two 2-pyridylmethyl pendant arms. 7Li NMR spectroscopy was used to investigation the stability and stoichiometry information of a Li+ complex with three symmetrical branched Schiff base (Sc.B.1), (Sc.B.2) and (Sc.B.3) in 0–100, 25–75, 50-50 and 75–25 w/w% acetonitrile – [(BMIM)(PF6)] ionic liquid mixture solution. A competitive 7Li NMR manner was also used to probe the complexation of Schiff bases with Mn2+, Zn2+ and Cd2+ ions in the same solvent systems. The stability constants of the resulting complexes were estimated from computer fitting of the mole ratio information to an equation that relates the observed chemical shifts to the stable constant. There is a reverse relevance of the complex stability and the amount of ionic liquid in the solvent mixture. In of the all experimented solvent mixture, the stability of the resulted 1:1 complexes were found to change in the order M-Sc.B.1>M-Sc.B.2>M-Sc.B.3 and Cd2+> Mn2+> Zn2+.
- Manesh, Abbas Amini,Zebarjadian, Mohammad Hasan
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- Hydroxylation of Aromatics by H2O2 Catalyzed by Mononuclear Non-heme Iron Complexes: Role of Triazole Hemilability in Substrate-Induced Bifurcation of the H2O2 Activation Mechanism
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Rieske dioxygenases are metalloenzymes capable of achieving cis-dihydroxylation of aromatics under mild conditions using O2 and a source of electrons. The intermediate responsible for this reactivity is proposed to be a cis-FeV(O)(OH) moiety. Molecular models allow the generation of a FeIII(OOH) species with H2O2, to yield a FeV(O)(OH) species with tetradentate ligands, or {FeIV(O); OH.} pairs with pentadentate ones. We have designed a new pentadentate ligand, mtL42, bearing a labile triazole, to generate an “in-between” situation. Two iron complexes, [(mtL42)FeCl](PF6) and [(mtL42)Fe(OTf)2]), were obtained and their reactivity towards aromatic substrates was studied in the presence of H2O2. Spectroscopic and kinetic studies reflect that triazole is bound at the FeII state, but decoordinates in the FeIII(OOH). The resulting [(mtL42)FeIII(OOH)(MeCN)]2+ then lies on a bifurcated decay pathway (end-on homolytic vs. side-on heterolytic) depending on the addition of aromatic substrate: in the absence of substrate, it is proposed to follow a side-on pathway leading to a putative (N4)FeV(O)(OH), while in the presence of aromatics it switches to an end-on homolytic pathway yielding a {(N5)FeIV(O); OH.} reactive species, through recoordination of triazole. This switch significantly impacts the reaction regioselectivity.
- Rebilly, Jean-No?l,Zhang, Wenli,Herrero, Christian,Dridi, Hachem,Sénéchal-David, Katell,Guillot, Régis,Banse, Frédéric
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supporting information
p. 659 - 668
(2019/12/27)
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- Systematic research of H2dedpa derivatives as potent inhibitors of New Delhi Metallo-β-lactamase-1
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New Delhi Metallo-β-lactamase-1 (NDM-1), a Zn (II)-dependent enzyme, can catalyze the hydrolysis of almost all β-lactam antibiotics including carbapenems, resulting in bacterial antibiotic resistance, which threatens public health globally. Based on our finding that H2dedpa is as an efficient NDM-1 inhibitor, a series of H2dedpa derivatives was systematically prepared. These compounds exhibited significant activity against NDM-1, with IC50 values 0.06–0.94 μM. In vitro, compounds 6k and 6n could restore the activity of meropenem against Klebsiella pneumoniae, Escherichia coli and Proteus mirabilis possessing either NDM or IMP. In particular, the activity of meropenem against E. coli producing NDM-4 could be improved up to 5333 times when these two compounds were used. Time–kill cell-based assays showed that 99.9% of P. mirabilis were killed when treated with meropenem in combination with compound 6k or 6n. Furthermore, compounds 6k and 6n were nonhemolytic (HC50 > 1280 μg/mL) and showed low toxicity toward mammalian (HeLa) cells. Mechanistic studies indicated that compounds 6k and 6n inhibit NDM-1 by chelating the Zn2+ ion of the enzyme.
- Bai, Meng-Meng,Cui, De-Yun,Han, Jiang-Xue,Kong, Hong-Tao,Liu, Yi-Shuang,Shen, Bo-Yuan,Wang, Cong-Cong,Xiao, Chun-Ling,Yan, Da-Chao,Yang, Yi,Zhang, En
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- Multidentate Pyridyl-Aminophosphinite and Pyridyl-Phosphoramidite Ruthenium(II) Complexes: Synthesis, Structure and Application as Levulinic Acid Hydrogenation Pre-Catalysts
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Novel multidentate pyridyl-aminophosphinite (L1) and pyridyl-phosphoramidite (L2) ligands of N^P^P^N-donor system have been synthesized via a series of simple steps. The ligands are symmetrical and as a result, their reactions with [Ru(p-cymene)Cl2]2 and [Ru(benzene)Cl2]2 lead to the formation of four monodentate bimetallic complexes (1–4) that retain the symmetry of the ligands. Meso and racemic mixtures (rac) of bidentate bimetallic complexes 5–8 were formed from the monodentate complexes through coordination of the pyridine nitrogen atoms to the two metal centers. The isomerism occurs at each metal center, which was evidenced by 31P{1H}, 1H NMR spectroscopy and single-crystal X-ray diffraction. The complexes were active towards hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) using formic acid as the hydrogen source. The complexes are active at relatively low temperatures and are able to perform the hydrogenation in the absence of any additional solvent apart from the reagents to give high TON of 3 600. The catalysts are recyclable up to the fourth cycle, following which 20 % loss of activity is seen.
- Amenuvor, Gershon,Rono, Charles K.,Darkwa, James,Makhubela, Banothile C. E.
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p. 3942 - 3953
(2019/09/17)
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- Ligand ratio/solvent-influenced syntheses, crystal structures, and magnetic properties of polydentate Schiff base ligand-Dy(iii) compounds with β-diketonate ligands as co-ligands
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Tuning the synthesis conditions and further regulating the magnetic dynamics of single-molecule magnets (SMMs) are crucial challenges for chemists. Some feasible approaches have been developed to understand magneto-structural correlations and regulate rel
- Zhang, Sheng,Mo, Wenjiao,Zhang, Zengqi,Gao, Fei,Wang, Lei,Hu, Dengwei,Chen, Sanping
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p. 12466 - 12481
(2019/08/26)
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- Large-Scale Synthesis of Symmetric Tetramine Ligands by Using a Modular Double Reductive Amination Approach
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Tetramine ligands play an important role in a broad range of transition metal catalyzed transformations. We here present a flexible and modular approach to this class of ligands using a double reductive amination strategy. Thus, the target molecules were prepared in a highly efficient manner in only three steps, from commercially available starting materials. Excellent overall yields, of up to 96 % were reached. Notably, chiral C 2-symmetric ligands are available using this procedure. All reactions are easily scalable and the tetramine ligands were obtained in excellent purity, while only a single chromatographic purification is required at the end of the three step sequence.
- Tretbar, Maik,Stark, Christian B. W.
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p. 6942 - 6946
(2017/12/26)
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- Synergetic oxidation of ethylbenzene to acetophenone catalyzed by manganese(II) complexes bearing pendant iodophenyl groups
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Five tetradentate ligands, L1–5, bearing the moiety of bis(pyridin-2-ylmethyl)amine (1) and their complexes with Mn(II) were prepared. All the compounds and metal complexes were appropriately characterized. The five manganese(II) complexes (3a–e) are of the formula, [Mn(II)LxCl2] (x = 1-5), as suggested by the crystal structure of complexes 3b and 3c. All the ligands except for L3 possess two iodobenzene groups via an ether linkage (except for L1) with various lengths. By using oxone as an oxidant, the catalytic activity of these complexes on the oxidation of ethylbenzene to acetophenone in acetonitrile/water at room temperature was studied. Our results showed that the pendant iodophenyl groups play a synergetic role with the metal center in the catalysis, and complex 3b possesses the most appropriate length of the linkage between the iodobenzene group and the metal center. EPR and FTIR data suggest that the metal center of the active species should be Mn(IV) after the oxidation of oxone under the reaction conditions. A catalytic mechanism was also proposed based on the experimental observations.
- Yang, Yiwen,Zhong, Wei,Nie, Binmei,Chen, Jiangmin,Wei, Zhenhong,Liu, Xiaoming
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p. 136 - 142
(2017/11/10)
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- A new ligand H4Lox and its iron(III) complex as a platform for the development of heterotrimetallic complexes
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The combination of multiple metal ions of different nature, in a single coordination compound, can provide a unique set of properties suitable for applications such as mimetization of the active site of enzymatic systems, development of new molecular magnetic materials and catalysts for photoinduced water splitting. Nonetheless, the preparation of heteromultimetallic complexes, in a controlled way, is a challenging task. In this work, we present a new ligand, H4Lox, designed as a platform for the synthesis of heterotrimetallic complexes. From H4Lox and its precursor H2L, two mononuclear iron(III) complexes, [Fe(L)]NO3·MeOH·2H2O (1) [Fe(H2Lox)]NO3·XH2O (2) were synthesized and fully characterized. The structure of 2 revealed a N2O2vacant coordination site comprised by two phenolate oxygen atoms and two oxime nitrogen atoms. DFT calculations and ESI-MS data demonstrate that complex 2 can accommodate two additional metal ions, in a stable heterotrimetallic complex. The effect of the ortho substituents of the phenolate groups (CHO and CNOH) in the electronic states of 1 and 2, respectively, was evaluated by UV–Vis spectroscopy, cyclic voltammetry and DFT calculations. A free energy correlation was found between the calculated electrophilicity index ω and the experimental half wave potentials of 1, 2 and their analogous complex [Fe(bbpen-Me)]+[33]. The electrophilicity index ω was used to estimate the FeIII/FeIIredox potential of the hypothetical [FeZnCl2(Lox)Ga(tpa)]2+complex.
- Firmo, Roberta Nunes,de Souza, Isabela Cristina Aguiar,Miranda, Fabio da Silva,Pinheiro, Carlos Basílio,Resende, Jackson Antonio Lamounier Carmargos,Lanznaster, Mauricio
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p. 604 - 611
(2016/07/22)
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- Comparative study of ring-opening polymerization of L-lactide and ε-caprolactone using zirconium hexadentate bis(aminophenolate) complexes as catalysts
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A series of zirconium bis(aminophenolate) complexes as catalysts for the ring opening polymerization of l-lactide (LA) and ε-caprolactone (CL) were investigated. Ligands bearing various chelating groups have a profound influence on the catalysis results. Among them, the thiophen-2-yl methyl group showed the greatest activity while the pyridine-2-yl methyl group showed the worst performance with regard to the rate of CL polymerization. However, the trend was reversed for the rate of LA polymerization. The kinetic results indicated a first-order dependency on [CL] and [LA]. However, the order of the catalyst concentration was different. Polymerization proceeded with second-order dependence on [LOMeZr(OBn)2] for CL but with first-order dependence on [LOMeZr(OBn)2] for LA.
- Ou, Hsiu-Wei,Chiang, Michael Y.,Vandavasi, Jaya Kishore,Lu, Wei-Yi,Chen, Yen-Jen,Tseng, Hsi-Ching,Lai, Yi-Chun,Chen, Hsuan-Ying
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p. 477 - 484
(2015/02/19)
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- Nitric oxide reactivity of a manganese(II) complex leading to nitrosation of the ligand
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Manganese(II) complexes, [Mn(L)(Cl)2], 1 and [Mn(L)(H2O)2](ClO4)2, 2 {L = N1,N2-bis((pyridine-2-yl)methyl)ethane-1,2-diamine} were prepared and characterized. In acetonitrile solution, complex 1 did not react with nitric oxide gas. However, addition of nitric oxide gas to the acetonitrile solution of complex 2 resulted in unstable Mn(II)-nitrosyl intermediate. The formation of nitrosyl intermediate was evidenced by UV-Vis, solution FT-IR, 1H NMR spectral studies. Subsequently, Mn(II) center in the complex 2 was undergone reduction to Mn(I) with a simultaneous N-nitrosation of the ligand. The N-nitrosated ligand was isolated and characterized. It should be noted that the corresponding Cu(II) complex of the same ligand in presence of nitric oxide was not found to yield Cu(II)-nitrosyl.
- Kalita, Aswini,Ghosh, Somnath,Mondal, Biplab
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p. 183 - 188
(2015/03/14)
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- Synchronizing steric and electronic effects in {RuII(NNNN,P)} complexes: The catalytic dehydrative alkylation of anilines by using alcohols as a case study
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A series of new hexacoordinated {RuII(NNNN,P)} complexes was prepared from [RuCl2(R3P)3]. Their structure was determined by X-ray crystallography. The catalytic potential of this new class of complexes was tested in the alkylation of aniline with benzyl alcohol. In this test reaction, the influence of the counteranion plus electronic influences at the tetradentate ligand and the phosphine ligand were examined. The electrochemistry of all complexes was studied by cyclic voltammetry. Depending on the substituent at the ligand backbone, the complexes showed a different behavior. For all N-benzyl substituted complexes, reversible Ru II/III redox potentials were observed, whereas the N-methyl substituted complex possessed an irreversible oxidation event at small scan rates. Furthermore, the electronic influence of different substituents at the ligand scaffold and at the phosphine on the RuII/III redox potential was investigated. The measured E0 values were correlated to the theoretically determined HOMO energies of the complexes. In addition, these HOMO energies correlated well with the reactivity of the single complexes in the alkylation of aniline with benzyl alcohol. The exact balance of redox potential and reactivity appears to be crucial for synchronizing the multiple hydrogen-transfer events. The optimized catalyst structure was applied in a screening on scope and limitation in the catalytic dehydrative alkylation of anilines by using alcohols.
- Weickmann, Daniel,Frey, Wolfgang,Plietker, Bernd
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p. 2741 - 2748
(2013/03/14)
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- Synthesis and structures of two cobalt(III) complexes with N4 donor ligands: Isolation of a unique bis-hemiaminal ether ligand as the metal complex
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Two cobalt(III) complexes, [CoL1(N3) 2]ClO4·H2O (1) and [CoL 2(N3)2]NO3 (2), where L1 = N,N′-bis-(2-pyridylmethyl)-1,2-ethanediamine, L2 = N,N′-bis-(1-methoxy-1-pyridin-2-yl-methyl)-ethane-1,2-diamine and both ligands are tetradentate N4 donors, have been prepared and characterized by elemental analysis, IR and UV-Vis spectroscopy, cyclic voltammetry and single crystal X-ray diffraction studies. Both compounds assume an asymmetric cis-octahedral (N2/N2) geometry. Complex 1 crystallizes in the orthorhombic space group Pbca with cell dimensions a = 9.7593(2) A?, b = 16.8640(3) A?, c = 25.8206(5) A?, Z = 8, whereas complex 2 crystallizes in the monoclinic space group P21/c with cell dimensions a = 14.437(3) A?, b = 15.596(3) A?, c = 19.187(3) A?, β = 93.642(2), Z = 8. In complex 2, a new bis-hemiaminal ether ligand was found to be "trapped". Hemiaminal ethers are known to be very unstable intermediates and no crystal structure of any bis-hemiaminal ether has been reported to date. Complex 2 represents a uniquely stable system containing the trapped bis-hemiaminal ether L2.
- Das, Mithun,Chattopadhyay, Shouvik
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p. 443 - 451
(2013/03/28)
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- Chemosensor activity of 2-(anthracen-9-yl)-substituted imidazolidines and hexahydropyrimidines
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A number of 2-(anthracen-9-yl)-substituted imidazolidines and hexahydropyrimidines were synthesized by reaction of N,N'-bis[aryl(hetaryl) methyl]ethylene-1,2-diamines and N,N'-bis[aryl(hetaryl)methyl]-propane-1,3- diamines with anthracene-9-carbaldehyde. The obtained compounds showed chemosensor activity toward Cd2+, Cu2+, and Hg2+ ions. Pleiades Publishing, Ltd., 2012.
- Tolpygin
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p. 104 - 108
(2012/05/20)
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- Complexation of N4-tetradentate ligands with Nd(III) and Am(III)
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To improve understanding of aza-complexants in trivalent actinide-lanthanide separations, a series of tetradentate N-donor ligands have been synthesized and their complexation of americium(III) and neodymium(III) investigated by UV-visible spectrophotometry in methanolic solutions. The six pyridine/alkyl amine/imine ligands are N,N′-bis(2-methylpyridyl)-1,2- diaminoethane, N,N′-bis(2-methylpyridyl)-1,3-diaminopropane, trans-N,N-bis(2-pyridylmethyl)-1,2-diaminocyclohexane (BPMDAC), N,N'-bis(2-pyridylmethyl)piperazine, N,N'-bis-[pyridin-2-ylmethylene]ethane-1,2- diamine, and trans-N,N-bis-([pyridin-2-ylmethylene]-cyclohexane-1,2-diamine. Each ligand has two pyridine groups and two aliphatic amine/imine N-donor atoms arranged with different degrees of preorganization and structural backbone rigidity. Conditional stability constants for the complexes of Am(III) and Nd(III) by these ligands establish the selectivity patterns. The overall selectivity of Am(III) over Nd(III) is similar to that reported for the terdentate bis(dialkyltriazinyl)pyridine molecules. The cyclohexane amine derivative (BPMDAC) is the strongest complexant and shows the highest selectivity for Am(III) over Nd(III) while the imines appear to prefer a bridging arrangement between two cations. These results suggest that this series of ligands could be employed to develop an enhanced actinide(III)- lanthanide(III) separation system.
- Ogden, Mark D.,Sinkov, Serguei I.,Meier, G. Patrick,Lumetta, Gregg J.,Nash, Kenneth L.
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p. 2138 - 2153
(2013/05/09)
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- Synthesis and evaluation of conformationally restricted N 4-tetradentate ligands for implementation in An(III)/Ln(III) separations
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The previous literature demonstrates that donor atoms softer than oxygen are effective for separating trivalent lanthanides (Ln(III)) from trivalent actinides (An(III)) (Nash, K.L., in: Gschneider, K.A. Jr., et al. (eds.) Handbook on the Physics and Chemistry of Rare Earths, vol. 18-Lanthanides/ Actinides Chemistry, pp. 197-238. Elsevier Science, Amsterdam, 1994). It has also been shown that ligands that "restrict" their donor groups in a favorable geometry, appropriate to the steric demands of the cation, have an increased binding affinity. A series of tetradentate nitrogen containing ligands have been synthesized with increased steric "limits". The pK a values for these ligands have been determined using potentiometric titration methods and the formation of the colored copper(II) complex has been used as a method to determine ligand partitioning between the organic and aqueous phases. The results for the 2-methylpyridyl-substituted amine ligands are encouraging, but the results for the 2-methylpyridyl-substituted diimines indicate that these ligands are unsuitable for implementation in a solvent extraction system due to hydrolysis. Springer Science+Business Media, LLC 2012.
- Ogden, Mark D.,Patrick Meier,Nash, Kenneth L.
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experimental part
p. 1 - 16
(2012/08/08)
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- MnII complexes with tetradentate N4 ligands: Highly efficient catalysts for the epoxidation of olefins with H2O 2
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A series of Mn-complexes with tetradentate N4 ligands, introducing aromatic groups into 2-pyridylmethyl positions of N,N′-dimethyl-N,N′-bis(2-pyridylmethyl)ethane-1,2-diamine (mep), N,N′-dimethyl-N,N′-bis(2-pyridylmethyl)cyclohexane-trans-diamine (mcp), have been synthesized and applied for epoxidation of olefins using H 2O2 as the oxidant. The Mn-complexes still possessed an octahedral mononuclear structure in a cis-α topology. These complexes showed good regioselectivity, high yields and turnover frequency (even up to 228,000 h-1) with low catalyst loading (0.1-0.01 mol%) for epoxidation of a family of olefins (including internal aromatic olefins, internal and terminal aliphatic olefins and diolefins).
- Yu, Songjie,Miao, Cheng-Xia,Wang, Daqi,Wang, Shoufeng,Xia, Chungu,Sun, Wei
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experimental part
p. 185 - 191
(2012/03/10)
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- Structural and spectroscopic characterization of N,N′-bis(2- pyridylmethyl)-ethylenediamine tetrahydrochloride dihydrate
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The crystal structure of the title compound, [(C5H 4NH)-CH2-NH2-(CH2) 2-NH2-CH2(C5H4NH)]Cl 4·2H2O, a potentially useful agent for chelation therapies, has been determined by single crystal X-ray diffractometry. It crystallizes in the monoclinic space group P21/c with Z = 2. The FT-IR and Raman spectra as well as the 1H and 13C NMR spectra of the compound were also recorded and briefly discussed.
- Zinczuk,Echeverría,Piro,Parajón-Costa,Baran
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experimental part
p. 302 - 305
(2011/07/30)
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- Thermo-responsive extraction of cadmium(II) ion with TPEN-NIPA gel. Effect of the number of polymerizable double bond toward gel formation and the extracting behavior
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N,N,N′,N′-(Tetrakis-2-pyridylmethyl)ethylenediamine (TPEN) derivatives bearing the different number (1-4) of a double bond moiety on the pyridine ring are synthesized and subjected to copolymerization with N-isopropylacrylamide in the presence of AIBN. The obtained poly(TPEN-NIPA) gels show thermo-responsive swelling/shrinking behaviors and are employed for the extraction of cadmium(II) ion from the aqueous solution to examine the relationship of the gel characteristics and the extraction performance. The polymer gels composed of the TPEN derivative bearing three or four double bonds exhibit temperature-dependent change of swelling and shrinking in water. These gels extract CdII ion efficiently from the aqueous solution in the swelling state at 5 °C, while little extraction was observed at 45 °C with shrinking.
- Fukuoka, Sachio,Kida, Tatsuya,Nakajima, Yasutaka,Tsumagari, Takayuki,Watanabe, Wataru,Inaba, Yusuke,Mori, Atsunori,Matsumura, Tatsuro,Nakano, Yoshio,Takeshita, Kenji
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experimental part
p. 1721 - 1727
(2010/04/04)
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- The unexpected role of pyridine-2-carboxylic acid in manganese based oxidation catalysis with pyridin-2-yl based ligands
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A number of manganese-based catalysts employing ligands whose structures incorporate pyridyl groups have been reported previously to achieve both high turnover numbers and selectivity in the oxidation of alkenes and alcohols, using H2O2 as terminal oxidant. Here we report our recent finding that these ligands decompose in situ to pyridine-2-carboxylic acid and its derivatives, in the presence of a manganese source, H2O 2 and a base. Importantly, the decomposition occurs prior to the onset of catalysed oxidation of organic substrates. It is found that the pyridine-2-carboxylic acid formed, together with a manganese source, provides for the observed catalytic activity. The degradation of this series of pyridyl ligands to pyridine-2-carboxylic acid under reaction conditions is demonstrated by 1H NMR spectroscopy. In all cases the activity and selectivity of the manganese/pyridyl containing ligand systems are identical to that observed with the corresponding number of equivalents of pyridine-2-carboxylic acid; except that, when pyridine-2-carboxylic acid is used directly, a lag phase is not observed and the efficiency in terms of the number of equivalents of H 2O2 required decreases from 6-8 equiv. with the pyridin-2-yl based ligands to 1-1.5 equiv. with pyridine-2-carboxylic acid.
- Pijper, Dirk,Saisaha, Pattama,De Boer, Johannes W.,Hoen, Rob,Smit, Christian,Meetsma, Auke,Hage, Ronald,Van Summeren, Ruben P.,Alsters, Paul L.,Feringa, Ben L.,Browne, Wesley R.
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supporting information; experimental part
p. 10375 - 10381
(2011/01/09)
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- An NBD-based colorimetric and fluorescent chemosensor for Zn2+ and its use for detection of intracellular zinc ions
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A new 7-nitrobenz-2-oxa-1,3-diazole (NBD) based colorimetric and fluorescence chemosensor for Zn2+, an ion involved in many biological processes, was designed and synthesized. The NBD-probe 1 displays a red-to-yellow color change and an enhancement of fluorescent intensity in the presence of an aqueous solution of Zn2+ ions (pH 7.2). Internal charge transfer (ICT) and photoinduced electron transfer (PET) mechanisms are responsible for these changes. The practical use of this probe was demonstrated by its application to the biologically relevant detection of Zn2+ ions in pancreatic β-cells.
- Xu, Zhaochao,Kim, Gun-Hee,Han, Su Jung,Jou, Min Jung,Lee, Chongmok,Shin, Injae,Yoon, Juyoung
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experimental part
p. 2307 - 2312
(2009/07/18)
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- Copper-catalyzed amidation of aryl iodides in the presence of various chelating ligands
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N,N′-Dibenzylethylenediamine is presented as a new, efficient, and versatile bidentate ligand suitable for the copper catalyzed formation of the C-N bond. This bidentate ligand has been demonstrated to facilitate the copper catalyzed cross-coupling reactions of aryl iodides with amides to afford the desired products in good to excellent yields.
- Hosseinzadeh, Rahman,Golchoubian, Hamid,Masoudi, Mahtab
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body text
p. 649 - 653
(2009/05/11)
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- Chromium(III) complexes of the hexadentate ligand N,N,N′,N′-tetrakis(2-pyridylmethyl)ethane-1,2-diamine. Synthesis, structure and reactivity
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Chromium(III) complexes of N,N,N′,N′-tetrakis(2-pyridylmethyl)ethane-1,2-diamine, tpen, have been synthesised by air oxidation of chromium(II) acetate and the ligand in a methanol-water mixture. Addition of perchlorate precipitates [Cr(tpen)(OCOCH3)](ClO4)2 · H2O, which has been used as the starting material for the synthesis of a number of complexes including [Cr(tpen)](ClO4)3, [Cr(tpen)(OH)](ClO4)2 and cis-[Cr(tpen)(OH)2]ClO4 · 3H2O. These compounds have all been characterised by single-crystal structure determinations. The four complexes are all monomeric and contain six-coordinate chromium(III) cations. In [Cr(tpen)]3+ all six nitrogens of the potentially hexadentate tpen ligand are coordinated to chromium, in [Cr(tpen)(OCOCH3)]2+ and [Cr(tpen)(OH)]2+ five nitrogen atoms are coordinated and in cis-[Cr(tpen)(OH)2]+ only four nitrogen atoms are coordinated. The remaining coordination sites in the last three cations are occupied by oxygen atoms of the acetate and the hydroxide ligands. In neutral solution the divalent base [Cr(tpen)(OH)]2+ is relatively stable, but acidification leads to a fast equilibration reaction between [Cr(tpen)(OH2)]3+ and [Cr(tpen)]3+, which has been characterized by stopped-flow measurements. In basic aqueous solution [Cr(tpen)(OH)]2+ reacts slowly to give cis-[Cr(tpen)(OH)2]+. Acidification of cis-[Cr(tpen)(OH)2]+ solutions leads to the same hexaamine/pentaamine equilibrium mixture but by a considerably slower process. Part of this significant reactivity difference may be attributed to the conformation of the coordinated part of the ligand, which is similar in the hexaamine and pentaamine complexes, and markedly different in the tetraamine complex.
- Eriksen,Goodson,Hazell,Hodgson,Michelsen,Monsted,Rasmussen,Toftlund
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p. 1083 - 1092
(2007/10/03)
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- Ion-molecule reactions in a quadrupole ion trap as a probe of the gas-phase structure of metal complexes
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A method is described in which the coordination number in metal complexes can be determined using ion-molecule reactions in a quadrupole ion trap mass spectrometer. Complexes of first-row transition metals in the +2 oxidation state, including manganese through zinc, are electrosprayed, isolated in the ion trap and allowed to react with gases. The coordination number is ascertained by observing the reagent ligands that successfully react with the complex. It was generally observed that six-coordinate complexes are unreactive, five-coordinate complexes react with pyridine and ethylamine, four-coordinate complexes react with pyridine, ethylamine and ammonia and three-coordinate complexes react with all the reagent ligands studied, including water and methanol. The order of reactivity for a given complex reacting with the various reagent ligands is found to follow the order of the electron-donating ability of the reagent ligands. In addition, the effect of the metal center on the reactivity of the complexes in the gas phase is analogous to solution-phase trends; electronic structure strongly influences the gas-phase reactions. These results were then used to predict the complexation behavior of novel podand ligands for which condensed phase information is not available. The results indicate that ion-molecule chemistry in the gas phase may be useful in predicting the interactions between novel multidentate ligands and metals in solution.
- Vachet, Richard W.,Hartman, Judith Ann R.,Callahan, John H.
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p. 1209 - 1225
(2007/10/03)
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- Synthesis, Reactivity and X-ray Structure of a Dinuclear Manganese(II) Complex of a Chelating Tertiary Amine, a Catalyst for the Oxidation of Alkanes and Olefins
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The molecular structure of 2+ (L = N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)ethane-1,2-diamine; OAc = acetate) has been characterised by X-ray analysis.The crystal is triclinic, space group P, with a = 13.702(2), b = 13.862(2), c = 14.855(5) Angstroem, α = 63.21(2), β = 64.01(2), γ = 71.21(1) deg, and Z = 2.The measured intramolecular Mn-Mn separation of 4.298 Angstroem indicates there is no metal-metal interaction.The Mn complex catalyses oxidation of saturated alkanes and olefins by iodosylbenzene and t-butyl hydroperoxide with high turnovers and yields under mild conditions.
- Che, Chi-Ming,Tang, Wai-Tong,Wong, Kwok-Yin,Wong, Wing-Tak,Lai, Ting-Fong
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p. 401 - 427
(2007/10/02)
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