Synthesis, characterization, magnetic properties, and topological aspects of isoskeletal heterometallic hexanuclear Co II 4 Ln III 2 coordination clusters possessing 2,3,4M6-1 Topology

The reaction of (E)-2-(2-hydroxy-3-methoxybenzylideneamino)phenol (H2L1) with Co(NO3)26H2O and LnCl3x(H2O) afforded a family of hexanuclear heterometallic coordination clusters (CCs) formulated as [CoII4LnIII2(µ3-OH)2(L1)4Cl2(NO3)2(MeOH)4] 3(Et2O) where Ln is Y (1), Gd (2), Dy (3), and Tb (4). All the compounds are stable in solution as confirmed by ESI-MS studies. The compounds can be described as twisted boat-like and possess a 2,3,4M6–1 topology. The reaction of (E)-2-(5-bromo-2-hydroxy-3-methoxybenzylideneamino)phenol (H2L2) with Co(NO3)26H2O and DyCl3x(H2O) afforded [CoII4DyIII2(µ3-OH)2(L2)4Cl2(NO3)2(MeOH)4] (5), which is isoskeletal to compounds 1–4. Magnetic studies performed over the temperature range 1.8–300 K show that compound 3 undergoes slow magnetic relaxation

Mechanism of Pyridine-Ligand Exchanges at the Different Labile Sites of 3d Heterometallic and Mixed Valence μ3-oxo Trinuclear Clusters

The syntheses and single crystal X-ray structural analysis of five novel hetero- and homometallic μ3-oxo trinuclear cluster with the formula [FeIII2MII(μ3-O)(μ-O2CCH3)6(4-Rpy)3] · x(4-Rpy) · y(CH3CN) where R ) Ph for 1(Fe2Mn),2(Fe2Fe), 3(Fe2Co), 4(Fe2Ni) and R ) CF3 for 5(Fe2Co), are reported. The persistence of the structure for compounds 2-5 in dichloromethane solution in the temperature range 190-320 K is demonstrated by 1H and 19F NMR spectroscopy. Even at the lowest temperature, the electron exchange in the homometallic mixed-valence compound 2(Fe2Fe) is in the fast regime at the NMR time scale. Variable temperature and pressure NMR line broadening allowed quantifying the fast coordinated/free 4-Rpy exchanges at the two labile metal centers in these clusters: 2: FeIII(k298/103 s-1 ) 16.6; ΔH‡ ) 60.32 kJ mol-1; ΔS‡ ) + 34.8 J K-1 mol-1; ΔV‡ ) + 12.5 cm3 mol-1); 3: Fe(11.9; 58.92; +30.7; +10.6) and Co (2.8; 68.24; +49.8; +13.9); 4: Fe(12.2; 67.91; +61.0; -) and Ni (0.37;78.62; +67.8; +12.3); 5: Fe (46; 58.21; +39.3; +14.2) and Co (4.7; 55.37; +11.2; +10.9). A limiting D mechanism is assigned to these exchange reactions. This assignment is based on a first-order rate law, the detection of intermediates, the positive and large entropies and volumes of activation. The order of reactivity kCo > kNi is expected for a D mechanism at these metal centers: their low exchange rates are due to their strong binding with the 4-Rpy donor. Surrounded by oxygen donors the d5 iron(III) usually reacts associatively; however, here due to low affinity of this ion for nitrogen the mechanism is D and the rate of exchange is very fast, even faster than on the divalent ions. There is no significant effect of the divalent ion in cluster 2, 3, and 5 on the exchange rates of 4-Phpy at the iron center, which seems to indicate that the specific electronic interactions between the three ions making the clusters do not influence the FeIII-N bond strength

Osmium-Nitrosyl Oxalato-Bridged Lanthanide-Centered Pentanuclear Complexes - Synthesis, Crystal Structures and Magnetic Properties

International audienceA series of pentanuclear heterometallic coordination compounds of the general formula (Bu 4 N) 5 [Ln{Os(NO)(μ-ox)-Cl 3 } 4 (H 2 O) n ] [Ln = Y (for 2) and Dy (for 3) when n = 0; Ln = Dy (for 3), Tb (for 4), and Gd (for 5) when n = 1] were synthesized by the reaction of the precursor (Bu 4 N) 2 [Os(NO)(ox)-Cl 3 ] (1) with the respective lanthanide(III) (Gd, Tb, Dy) or yttrium(III) chloride. For the five new complexes, the coordination numbers eight or nine are found for the central metal ion. The compounds were fully characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction analysis, magnetic susceptibility measurements, and ESI mass spectrometry. In addition, compound 1 was studied by UV/Vis spectroscopy and cyclic voltammetry. The X-ray dif-fraction analyses revealed that the anionic complexes consist of a lanthanide or yttrium core bridged through oxalato li-gands to four octahedral osmium-nitrosyl moieties. This picture , in which the central ion is eight-coordinate, holds fo

SANÇÕES ADMINISTRATIVAS APLICADAS NA AVIAÇÃO: UMA ANÁLISE DOS PRINCÍPIOS APLICÁVEIS AOS PROCESSOS ADMINISTRATIVOS NA AVIAÇÃO

TCC(graduação) - Universidade Federal de Santa Catarina. Centro de Ciências Jurídicas. Direito.O presente trabalho busca averiguar se o processo administrativo sancionatório na aviação cumpre os princípios da lei dos processos administrativos (lei 9.784/99). O estudo se faz relevante pois é um campo ainda pouco estudado e precisa ser tratado com seriedade já que é uma das formas de demonstração do ius puniendi estatal. O objetivo do trabalho é verificar se os processos administrativos que resultam em multas para os operadores de aeronaves cumprem os princípios constitucionais e legais. Sendo assim, será desenvolvido um estudo sobre os aspectos que envolvem as sanções administrativas. Além disso, será trabalhado sobre os limites da presunção de veracidade da Administração Pública, bem como será investigada a relação entre os princípios da lei dos processos administrativos (lei 9.784/99) com os processos administrativos em estudo. Ao final, será apresentada uma análise de dois processos administrativos relacionados ao tema em discussão. Nessa análise é possível identificar algumas falhas da Administração Pública, tanto na concepção do processo administrativo em questão (normas aplicadas através de Portarias) quanto no desenvolvimento com relação aos princípios que deveriam ser observados. Percebe-se, por fim, a necessidade de aperfeiçoar o processo administrativo no seio da Junta de Julgamento de Aeronáutica, órgão responsável por todo o desenvolvimento desse processo. Essa pesquisa serve para apontar apenas alguns dos aspectos mais relevantes que necessitam uma posterior atenção e um número maior de estudos na área para que haja uma evolução nesse ramo do Direito

Effects of terminal substitution and iron coordination on antiproliferative activity of L-proline-salicylaldehyde-thiosemicarbazone hybrids

A series of five iron(III) complexes, namely [Fe(HL1)Cl2] (1), [Fe(HL2)Cl2]·1.6H2O (2·1.6H2O), [Fe(HL3)(MeOH)Cl2]·0.5H2O (3·0.5H2O), [Fe(HL4)(MeOH)Cl2]·0.5H2O (4·0.5H2O) and [Fe(HL4)(DMF)Cl2]·0.5Et2O·H2O (4′·0.5Et2O·H2O), where H2L1 = l‐proline‐salicylaldehyde–thiosemicarbazone (l‐Pro‐STSC), H2L2 = pyrrolidine‐substituted l‐Pro‐STSC, H2L3 = phenyl‐substituted l‐Pro‐STSC, and H2L4 = naphthyl‐substituted l‐Pro‐STSC, have been synthesized. The two ligand precursors (H2L3 and H2L4) and iron complexes were characterized by elemental analysis, spectroscopic methods (UV/Vis, IR, and NMR), ESI mass spectrometry, cyclic voltammetry, and single‐crystal X‐ray crystallography (1–3 and 4′). Magnetic properties of the five‐coordinate complex 2 and six‐coordinate complex 4 have also been investigated. The antiproliferative activity of the organic hybrids and their iron(III) complexes have been studied in vitro in five human cell lines and one murine cancer cell line, namely HeLa (cervical cancer), FemX (melanoma), A549 (alveolar basal adenocarcinoma), LS‐174 (colon cancer), MDA‐MB‐453 (breast cancer) and MS1 (transformed murine endothelial), as well as in human noncancerous fetal lung fibroblast cell line (MRC‐5). According to the structure–activity relationship, introduction of aromatic groups such as phenyl or naphthyl enhances the cytotoxic potency of the hybrids in the following order H2L1 < H2L2 < H2L3 < H2L4. Coordination of the hybrids to iron(III) improves their antiproliferative activity in the majority of investigated cell lines with exception of H2L3 in LS‐174, H2L4 in MS1, and both H2L3 and H2L4 in FemX cell lines, where an opposite effect was observed.This study was financially supported by the Austrian Science Fund (project number P28223 N34), Research and Development Agency of the Slovak Republic under the contracts No. APVV 15-0079 and APVV-15-0053, Scientific Grant Agency of the Slovak Republic (VEGA Project 1/0871/16) and Slovak University of Technology in Bratislava (Young Researcher Grant, M. Milunović, PhD) This work was also supported by Ministry of Education, Science, Research and Sport of the Slovak Republic withinhe Research and Development Operational Program for the project "University Science Park of STU Bratislava", ITMS 26240220084, cofunded by the European Regional Development Fund

The Ruthenium Nitrosyl Moiety in Clusters: Trinuclear Linear μ-Hydroxido Magnesium(II)-Diruthenium(II), μ3-Oxido Trinuclear Diiron(III)–Ruthenium(II), and Tetranuclear μ4-Oxido Trigallium(III)-Ruthenium(II) Complexes

The ruthenium nitrosyl moiety, {RuNO}6, is important as a potential releasing agent of nitric oxide and is of inherent interest in coordination chemistry. Typically, {RuNO}6 is found in mononuclear complexes. Herein we describe the synthesis and characterization of several multimetal cluster complexes that contain this unit. Specifically, the heterotrinuclear μ3-oxido clusters [Fe2RuCl4(μ3-O)(μ-OMe)(μ-pz)2(NO)(Hpz)2] (6) and [Fe2RuCl3(μ3-O)(μ-OMe)(μ-pz)3(MeOH)(NO)(Hpz)][Fe2RuCl3(μ3-O)(μ-OMe)(μ-pz)3(DMF)(NO)(Hpz)] (7·MeOH·2H2O) and the heterotetranuclear μ4-oxido complex [Ga3RuCl3(μ4-O)(μ-OMe)3(μ-pz)4(NO)] (8) were prepared from trans-[Ru(OH)(NO)(Hpz)4]Cl2 (5), which itself was prepared via acidic hydrolysis of the linear heterotrinuclear complex {[Ru(μ-OH)(μ-pz)2(pz)(NO)(Hpz)]2Mg} (4). Complex 4 was synthesized from the mononuclear Ru complexes (H2pz)[trans-RuCl4(Hpz)2] (1), trans-[RuCl2(Hpz)4]Cl (2), and trans-[RuCl2(Hpz)4] (3). The new compounds 4-8 were all characterized by elemental analysis, ESI mass spectrometry, IR, UV-vis, and 1H NMR spectroscopy, and single-crystal X-ray diffraction, with complexes 6 and 7 being characterized also by temperature-dependent magnetic susceptibility measurements and Mössbauer spectroscopy. Magnetometry indicated a strong antiferromagnetic interaction between paramagnetic centers in 6 and 7. The ability of 4 and 6-8 to form linkage isomers and release NO upon irradiation in the solid state was investigated by IR spectroscopy. A theoretical investigation of the electronic structure of 6 by DFT and ab initio CASSCF/NEVPT2 calculations indicated a redox-noninnocent behavior of the NO ancillary ligand in 6, which was also manifested in TD-DFT calculations of its electronic absorption spectrum. The electronic structure of 6 was also studied by an X-ray charge density analysis

Transition metal complexes of a versatile polyalkoxy oxazolidine-based ligand derived from in situ cyclization

YesOne-pot reaction between 8-hydroxyquinoline-2-carboxaldehyde (HQC) and tris(hydroxymethyl)aminomethane (TRIS) followed by in situ cyclization yielded an oxazolidine based ligand which produced four mononuclear complexes of MnII(1), CoII(2), NiII(3), ZnII(4), a tetranuclear iron (FeIII4) complex (5) and a trinuclear cobalt (CoIICoIII2) complex (6). Magnetic studies show dominant antiferromagnetic interaction in tetranuclear iron (FeIII4) complex 5 and presence of the slow relaxation of magnetisation in 6. The compounds were also studied for their antibacterial properties. The oxazolidine ligand (H3L2) of this study showed good antimicrobial activity not only against Gram-positive bacteria but against Gram-negative bacteria too. The antimicrobial efficacy of the metal complexes (1–6) is also reported.The full-text of this article will be released for public view at the end of the publisher's embargo period on 11 Apr 2019

Chiral single-molecule magnet with a 35K energy barrier for relaxation of the magnetization

International audienceThe reaction of [MnII(S-mandelato)2] complexes with 5-Methyl-salicylaldoxim (5-Me-saloxH2) leads to the chiral hexanuclear manganese(III) complex [Mn6(μ3-O)2(5-Me-salox)6(S-mandelato)2(EtOH)6]. The structure can be viewed as two neutral stacked {Mn3(μ3-O)(5-Me-salox)3(S-mandelato)(EtOH)3} triangular subunits linked together in a head-to-tail manner by two phenoxo and two oximato μ3-oxygen atoms of the deprotonated oxime groups of the ligands. The magnetic study of this chiral hexanuclear manganese(III) complex reveals a SMM behaviour with an energy barrier of the slow relaxation of the magnetisation equal to 35 K. Considering the structural features, the fitting of the temperature dependence of the magnetic susceptibility gives a good agreement with the experimental data considering two sets of interactions: J1 = +0.37 cm−1 and J2 = −0.70 cm−1 within (ferromagnetic) and between (antiferromagnetic), respectively, the {Mn3(μ3-O)(5-Me-salox)3(S-mandelato)(EtOH)3} triangular subunits.La réaction du complexe [MnII(S-mandélato)2] avec le 5-méthyl-salicylaldoxime (5-Me-saloxH2) donne un complexe hexanucléaire chiral de manganèse(III) [MnIII6(μ3-O)2(5-Me-salox)6(S-mandélato)2(EtOH)6]. La structure est constituée de deux sous-unités neutres {Mn3(μ3-O)(5-Me-salox)3(S-mandélato)(EtOH)3} triangulaires assemblées tête-bêche par deux atomes d’oxygène phenoxo et deux atomes d’oxygène oximato μ3 des groupes oxime déprotonés des ligands. L’étude magnétique de ce complexe hexanucléaire chiral de manganèse(III) révèle un comportement SMM avec une barrière d’énergie de la relaxation lente de l’aimantation égale à 35 K. Prenant en compte les caractéristiques structurales, la variation thermique de la susceptibilité magnétique donne un bon accord avec les données expérimentales en considérant une interaction J1 = +0,37 cm−1 dans les sous-unités triangulaires {Mn3(μ3-O)(5-Me-salox)3(S-mandélato)(EtOH)3} et une interaction antiferromagnétique J2 = −0,70 cm−1 entre les deux sous-unités