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Metals
Kinds of Metals Terms modified by Metals Selected AbstractsMAKING METAL AND FORGING RELATIONS: IRONWORKING IN THE BRITISH IRON AGEOXFORD JOURNAL OF ARCHAEOLOGY, Issue 4 2007MELANIE GILES Summary. This article explores the social significance of metalworking in the British Iron Age, drawing ethnographic analogies with small-scale, pre-industrial communities. It focuses on iron, from the collection of ore to smelting and smithing, challenging the assumption that specialized ironworking was necessarily associated with hierarchical chiefdoms, supported by full-time craft specialists. Instead, it explores more complex ways in which social and political authority might have been associated with craftwork, through metaphorical associations with fertility, skill and exchange. Challenging traditional interpretations of objects such as tools and weapons, it argues that the importance of this craft lay in its dual association with transformative power, both creative and destructive. It suggests that this technology literally made new kinds of metaphorical relationships thinkable, and it explores the implications through a series of case studies ranging from the production and use of iron objects to their destruction and deposition. [source] POTS, HOUSES AND METAL: TECHNOLOGICAL RELATIONS AT THE BRONZE AGE TELL AT SZÁZHALOMBATTA, HUNGARYOXFORD JOURNAL OF ARCHAEOLOGY, Issue 2 2006JOANNA SOFAER Summary. At the Bronze Age tell of Százhalombatta, Hungary, techniques used for making pottery echo those used in other media. Pottery and architecture have a close relationship. Not only were both made of clay, but methods of making pots echo those used for building. Similarly, pottery and metalwork share common themes and technologies for working with clay and bronze. Since choices made by potters are not solely confined to the environment, raw materials and tools, but are also socially and culturally defined, by implication the transfer of know-how must be situated within social networks between people. This paper considers how the identification of technical relationships between different media at Százhalombatta can be used to explore social relations in Bronze Age society, thereby suggesting relationships that work on both technical and social levels. [source] MARKET REVIEW: BASE METALS: Uncertainty Over?AFRICA RESEARCH BULLETIN: ECONOMIC, FINANCIAL AND TECHNICAL SERIES, Issue 7 2010Article first published online: 1 SEP 2010 No abstract is available for this article. [source] BASE METALS: South AfricaAFRICA RESEARCH BULLETIN: ECONOMIC, FINANCIAL AND TECHNICAL SERIES, Issue 1 2009Article first published online: 9 MAR 200 No abstract is available for this article. [source] Coselection for microbial resistance to metals and antibiotics in freshwater microcosmsENVIRONMENTAL MICROBIOLOGY, Issue 9 2006Ramunas Stepanauskas Summary Bacterial resistances to diverse metals and antibiotics are often genetically linked, suggesting that exposure to toxic metals may select for strains resistant to antibiotics and vice versa. To test the hypothesis that resistances to metals and antibiotics are coselected for in environmental microbial assemblages, we investigated the frequency of diverse resistances in freshwater microcosms amended with Cd, Ni, ampicillin or tetracycline. We found that all four toxicants significantly increased the frequency of bacterioplankton resistance to multiple, chemically unrelated metals and antibiotics. An ampicillin-resistant strain of the opportunistic human pathogen Ralstonia mannitolilytica was enriched in microcosms amended with Cd. Frequencies of antibiotic resistance were elevated in microcosms with metal concentrations representative of industry and mining-impacted environments (0.01,1 mM). Metal but not antibiotic amendments decreased microbial diversity, and a weeklong exposure to high concentrations of ampicillin (0.01,10 mg l,1) and tetracycline (0.03,30 mg l,1) decreased microbial abundance only slightly, implying a large reservoir of antibiotic resistance in the studied environment. Our results provide first experimental evidence that the exposure of freshwater environments to individual metals and antibiotics selects for multiresistant microorganisms, including opportunistic human pathogens. [source] A Microporous Metal,Organic Framework with Immobilized ,OH Functional Groups within the Pore Surfaces for Selective Gas SorptionEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 24 2010Zhenxia Chen Abstract A new two-dimensional microporous metal,organic framework Cu(BDC-OH)(H2O)·0.5DEF [abbreviation: Cu(BDC-OH); H2BDC-OH = 2-hydroxybenzene-1,4-dicarboxylic acid; DEF = diethylformamide] with functional OH groups on the pore surfaces was solvothermally synthesized and structurally characterized. The activated Cu(BDC-OH) exhibits a moderate Langmuir surface of 584 m2,g,1, a pore volume of 0.214 cm3,g,1, and C2H2/CH4 and CO2/CH4 selectivity of 6.7 and 9.3, respectively, at 296 K, thereby highlighting the promise for its application in gas separation. [source] Eight-Coordinate Endohedral Rhenium, Osmium and Iridium Atoms in Rare-Earth Halide Cluster ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2010Sina Zimmermann Abstract Endohedral (interstitial) atoms are essential for almost all of the rare-earth halide cluster complexes. Most of these contain octahedral clusters, some are isolated, but the majority exhibits condensation by common edges to structures of higher dimensionality. Higher coordination numbers of the endohedral atoms are rare. Four examples of extended cluster complexes with eight-coordinate endohedral atoms of sixth-period elements (Re, Os, Ir) are presented. In the quasi-isostructural, non-isotypic halides {ReGd4}Br4 and {OsSc4}Cl4, square antiprisms of gadolinium and scandium atoms, respectively, are connected by two common faces to chains, surrounded and loosely connected by halogenido ligands. The Re and Os atoms build a slightly bent chain with only little bonding interactions. Chemical bonding is dominated by endohedral atom,cluster atom and cluster atom,halide interactions. The same is true for the two scandium bromides {Ir3Sc12}Br16 and {Os3Sc12}Br16Sc, which contain chains of face-sharing square antiprisms and cubes in a ratio of 2:1. Metal,metal bonding is attested by short distances between those endohedral Ir and Os atoms, respectively, which center the square antiprisms (283 pm and 290 pm, respectively). Magnetic and conductivity measurements on {Ir3Sc12}Br16 reveal paramagnetism and a small-band-gap semiconductor. This is in accord with electronic structure calculations. [source] A Chiral Metal,Organic Framework Based on Heptanuclear Zinc CoresEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2009Hai-Yang Liu Abstract Two zinc(II) complexes, [Zn9(L1)6(H2O)2]·13.5H2O (1) and [Zn9(L2)6(H2O)3]·C2H5OH·8.5H2O (2), were synthesized. Both 1 and 2 are constructed from molecular building units (MBUs) that contain heptanuclear zinc clusters as cores. By introducing an additional chiral site into the original ligand, we achieved the transformation of the MOF from a nonchiral to a chiral structure, which provides a new strategy for designing chiral compounds. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Synthesis and Structure Characterization of Copper Terephthalate Metal,Organic FrameworksEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2009Cantwell G. Carson Abstract In this paper, we report on a high-throughput (gram quantities) solvothermal method for the synthesis of copper terephthalate metal,organic frameworks in dmf. While the structure of MOF-2 and some of the associated polymorphs are well known, we know of no equivalent structural studies for the isostructural copper terephthalate (Cu,tpa). The material we have made crystallizes in the C2/m space group. Cu,tpa also exhibits reversible solvent-exchange properties. These properties make this material useful for potential applications in gas storage and catalysis applications. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Vanadium Carbonyl Nitrosyl Compounds: The Carbonyl Nitrosyl Chemistry of an Oxophilic Early Transition MetalEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 12 2009Hongyan Wang Abstract The vanadium carbonyl nitrosyl compounds V(NO)(CO)n (n = 5, 4, 3) and V2(NO)2(CO)n (n = 9, 8, 7) have been examined by density functional theory in order to assess the effect of the oxophilicity of vanadium on its metal carbonyl nitrosyl chemistry. The expected octahedral structure for the experimentally known, but surprisingly unstable, V(NO)(CO)5, is confirmed by DFT. The optimized structures of the unsaturated derivatives V(NO)(CO)4 and V(NO)(CO)3 can be derived from the octahedral V(NO)(CO)5 structure by loss of one or two carbonyl groups, respectively. This leads to anearly square-planar predicted structure for V(NO)(CO)3. The lowest energy structures for the binuclear derivatives V2(NO)2(CO)n (n = 9, 8, 7) have exclusively two-electron donor carbonyl groups and three-electron donor linear nitrosyl groups with metal,metal distances corresponding to the formal bond orders required for the favored 18-electron configurations. Bridging carbonyl groups appear to be preferred energetically over bridging nitrosyl groups in the V2(NO)2(CO)n structures in contrast to the similar carbonyl nitrosyl compounds of later transition metals. The saturated V2(NO)2(CO)9, with a relatively long V,V distance of 3.583 Å (B3LYP) or 3.205 Å (BP86), is thermodynamically unstable with respect to dissociation into V(NO)(CO)5 + V(NO)(CO)4.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Do Metal,Metal Multiply-Bonded "Ligands" Have a trans Influence?EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 36 2008Magnetic Comparisons of Heterometallic CrCr···Co, MoMo···Co Interactions, Structural Abstract Reported here are two new compounds containing either a CrCr···Co [1, CrCrCo(dpa)4Cl2, dpa = 2,2,-dipyridylamide] or a MoMo···Co [2, MoMoCo(dpa)4Cl2] framework both having a multiply-bonded unit (CrCr in 1, MoMo in 2) in close proximity to the Co2+ ion and trans to a Co,Cl bond. Variable temperature magnetic susceptibility measurements reveal 1 to have a temperature-dependent spin equilibrium between a low-spin (S = 1/2) and high-spin (S = 3/2) state, whereas the Co2+ ion in 2 exists solely in its high-spin state. The crystal structures of 1 and 2 were determined. Variable temperature crystallographic data of 1 at 100 K and at room temperature reveal that the spin-transition affects not only the Co,ligand bond lengths but also the terminal Cr,ligand bond lengths. Whereas the Cr···Co distance becomes shorter by 0.13 Å in the low-spin form, the Co,Cldistance becomes longer by 0.2 Å. These observations,along with the crystal structure of 2, suggest that the multiply-bonded MM group has a trans influence on the Co2+ ion.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Alkali Metal (Li+,Cs+) Salts with Hexafluorochromate(V), Hexafluorochromate(IV), Pentafluorochromate(IV), and Undecafluorodichromate(IV) AnionsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2008Zoran Mazej Abstract The compounds ACrF6 (A = Li,Cs) were prepared by photochemical reactions of AF/CrF3 mixtures in anhydrous HF with elemental F2 at ambient temperature. The crystal structures of compounds ACrF6 (A = K,Cs) are analogous to that of KOsF6, and NaCrF6 exhibits polymorphism. The trigonal phase (II) can be classified to have the well-known LiSbF6 type of structure, while the crystal structure of the orthorhombic modification (I) appears to be a new structure-type. Thermal decomposition of the ACrF6 salts produce ACrF5(A = Rb, Cs), ACrF5/A2CrF6 (A = K), or A2CrF6 (A = Li, Na). These compounds undergo partial solvolysis in anhydrous HF with precipitation of CrF4. From the remaining solutions of the [CrF6]2, anions and dissolved AF (A = Li,Cs), single crystals of ACrF5 (A = K,Cs), A2CrF6·2HF (A = Na, K), A2CrF6·4HF (A = Rb, Cs), Li2CrF6, and K3Cr2F11·2HF were grown, and their crystal structures determined. The main structural feature of the ACrF5 compounds is the infinite zig-zag [CrF5]nn, chain of distorted [CrF6] octahedra joined by cis vertices. The crystal structures of A2CrF6·2HF (A = Na, K) and A2CrF6·4HF (A = Rb, Cs) consist of distorted [CrF6]2, octahedra involved in moderate to strong hydrogen bonding with HF molecules, while two A+ cations compensate the negative charge of each octahedron. In Na2CrF6·2HF, two neighboring HF molecules are involved in moderate to strong hydrogen bonding with each other. (HF)2 dimers with a parallelogram structure are formed. The mutual interactions in the crystal structure of K2CrF6·2HF differ from those found in Na2CrF6·2HF. In the former, each HF molecule interacts with the [CrF6]2, anion and three K+ cations. A2CrF6·4HF compounds of Rb and Cs are isostructural. Their structures consist of A+ cations and [CrF6]2, anions involved in hydrogen bonding with two sets of HF molecules in the trans position. The crystal structure of K3Cr2F11·2HF reveals a rare case of the [M2F11]3, anion. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Novel (3,4)- and (4,5)-Connected Lanthanide Metal,Organic FrameworksEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2008Xian-Wen Wang Abstract The three-dimensional lanthanide noninterpenetrating metal,organic frameworks formulated as [Ln(3,5-pdc)(C2O4)0.5(H2O)2]·H2O (Ln = LuIII, GdIII, TmIII and YbIII for complex 1,4, respectively; 3,5-pdc = 3,5-pyridinedicarboxylate) were synthesized by hydrothermal reactions of 3,5-H2pdc with lanthanide oxide and perchloric acid. Compound 1 shows (3,4)-connected (4.82)(4.85) dmc-type topological network, and complexes 2,4 display the novel (4,5)-connected (44.6.8)(44.62.84) xww-type topology. The lanthanide-mediated transformation of CO2 to oxalate under hydrothermal conditions was observed. The fluorescence properties of complexes 1,4 were investigated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Construction of 1D and 2D Copper(I) Coordination Polymers Assembled by PhS(CH2)nSPh (n = 1, 2) Dithioether Ligands: Surprising Effect of the Spacer Length on the Dimensionality, Cluster Nuclearity and the Fluorescence Properties of the Metal,Organic Framework,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2007Harmel N. Peindy Abstract Treatment of CuI with PhSCH2SPh in MeCN solution affords, by a self-assembly reaction, the monodimensional metal,organic coordination polymer [Cu4I4{,-PhS2CH2SPh}2]n (1), in which Cu4(,3 -I)4 cluster units are linked by the dithioether ligand in a 1D necklace structure. In contrast, the reaction of PhSCH2CH2SPh with CuI results in the formation of the metallopolymer [(CuI)2{,-PhS(CH2)2SPh}2]n (2). The 2D network of 2 is built from dimeric Cu2I2 units which are connected by 1,2-bis(phenylthio)ethane bridging ligands. The solid-state luminescence spectrum of 1 exhibits a strong emission around 532 nm, whereas a weak emission centred at 413 nm is observed in the case of 2. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Structural and Theoretical Insights into Metal,Scorpionate Ligand ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 10 2007Matthias Schwalbe Abstract The syntheses of the complexes [M(TmMe)(CO)2(NO)] (M = Mo, W) by reaction of NOBF4 with [M(TmMe)(CO)3], are reported and their spectroscopic characterisation and crystal structures are described. The analogous Cr complex could not be prepared by this methodology. The complexes adopt the expected pseudo-octahedral geometry. Complexes [M(L)(CO)2(NO)] (M = Cr, Mo, W; L = Cp, Tp and TmMe) together with the hypothetical [Mo(CO)2(NO)]+ cation were subjected to DFT calculations. Geometry-optimised structures closely parallel the crystallographic determinations and indicate that the complex [Cr(TmMe)(CO)2(NO)] is not inherently unstable. The DFT calculations allow the assignment of the C,O and N,O stretches in the IR spectrum and give insight into both the M,NO bonding and the metal to tripodal ligand bonding. The electron-donor strengths are confirmed to lie in the order TmMe > Tp > Cp. A side reaction of the B,H moiety of the TmMe anion with NO+ results in the isolation of the dimethylformamide adduct of (trismethimazolyl)borane, providing further evidence that the reaction pathways of the TmR ligands are more varied and less passive than in the chemistry of the nitrogen-based scorpionates.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Highly Symmetrical Tetranuclear Cluster Complexes Supported by p - tert -Butylsulfonylcalix[4]arene as a Cluster-Forming LigandEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2006Takashi Kajiwara Abstract Square-planar tetranuclear clusters [M4(L)(AcO)4(,4 -OH)], (M = MnII, CoII, and NiII) are synthesized using tetra-anionic p - tert -butylsulfonylcalix[4]arene (L4,) as a cluster-forming ligand. Three complexes are crystallographically isostructural, being crystallized in the triclinic crystal system with space group P. The calix[4]arene acts as a tetrakis fac -tridentate ligand through four phenoxo and four sulfonyl oxygen atoms to form square arrangement of four metal ions, which are further bridged by four chelating acetate ions and one hydroxo ion in a ,4 manner to complete the hexacoordination of each metal center. Although the whole molecule of each complex is crystallographically independent, the molecule is highly symmetrical with a pseudo-four-fold axis lying on the ,4 -OH, group. The tetranuclear clusters are stable enough to maintain the core structures even in highly dilute solution (,10 ,M), which was confirmed by mass spectroscopic study, however, bridging acetates were easily exchanged by other carboxylate chelates to form derivatives such as [M4(L)(BzO)4(OH)],. Metal,metal interactions were investigated by means of magnetic susceptibility, and it was revealed that both ferro- and antiferromagnetic interactions occur in the NiII complex depending on the bridging angles of Ni,O,Ni. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Theoretical Studies on Metal,Metal Interaction and Intrinsic 1,3[,*(d),(s/p)] Excited States of Dinuclear d10 Complexes with Bridging Phosphane LigandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 5 2006Qing-Jiang Pan Abstract To explore the metal,metal interaction and spectroscopic properties, the ground- and excited-state structures of [M2(dpm)2]2+ [M = Ag (2), Cu (3), dpm = bis(diphosphanyl)methane] and their solvated species [M2(dpm)2]2+·(MeCN)2 were optimized by the MP2 and CIS methods, respectively. In the ground states, the calculated M,M distances and their corresponding M,M stretching frequencies for 2 and 3 indicate the presence of metallophilic attraction; there is strong N,Cu/Ag coordination in acetonitrile, which is different from the case in previous studies of [Au2(dpm)2]2+ (1). CIS calculations show that 2 and 3 have 1,3[,*(d),(s/p)] as their lowest-energy excited state, as is also the case for 1, confirmed by unrestricted MP2 calculations. On the basis of the CIS-optimized structures, the TD-DFT (B3LYP) method was employed to calculate the emission spectra of such complexes. For 3, the phosphorescent emissions were calculated at 424 and 514 nm in the solid state and acetonitrile, which is comparable to the experimental data of 475 and 480 nm, respectively. The comparison between the gas-phase and solution emissions for 1,3 reveals that the N,M coordination results in a large red-shift of the emission wavelength. Taking previous studies into account , we found that the M,M distances are linearly correlated with the M,M stretching frequencies for the dinuclear d10 complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Synthesis, Characterization, and Electrochemical Properties of Novel Transition Metal,Fullerene Complexes Containing Di- and Tetraphosphane LigandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2006Li-Cheng Song Abstract This paper reports the synthesis, characterization, and some properties of transition metal,fullerene complexes containing trans -1,1,-bis(diphenylphosphanyl)ethylene (dppet, trans -Ph2PCH=CHPPh2) and N,N,N,,N,-tetra(diphenylphosphanylmethyl)ethylene diamine (dppeda, [(Ph2PCH2)2NCH2]2), including [(,2 -C60M)(dppet)2] (M = Pt 1, Pd 2), [(,2 -C60M)(dppet)]2 (M = Pt 3, Pd 4), [(,2 -C60Pd)(,2 -C60Pt)(dppet)2](5), [(,2 -C60Pd)(,2 -C70Pd)(dppet)2] (6), [(,2 -C70Pd)(dppet)]2 (7), [(,2 -C60M)(dppeda)] (M = Pt 8, Pd 9), and [(,2 -C60M)2(dppeda)] (M = Pt 10, Pd 11). Interestingly, while complexes 1, 2, 8, and 9 are the first examples of metallacyclopropafullerene diphosphane ligands containing fullerene cores, complexes 3,7, 10, and 11 are the first group 10 metal-containing, dumbbell-shaped bisfullerenes. All the complexes 1,11 were characterized by elemental analysis, spectroscopy, and, particularly for 4 and 5, by X-ray crystallography and cyclic voltammetry. Pathways for the formation of 1,11 are suggested. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] One-Dimensional Oxalato-Bridged Metal(II) Complexes with 4 - Amino-1,2,4-triazole as Apical LigandEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 21 2005Urko García-Couceiro Abstract The synthesis, chemical characterization, thermal behavior and magnetic properties of six new one-dimensional oxalato-bridged metal(II) complexes of formula [M(,-ox)(4atr)2]n [MII = Cu (1), Ni (2), Co (3), Zn (4), Fe(5)] and [Cd(,-ox)(4atr)2(H2O)]n (6) (ox = oxalato dianion, 4atr = 4-amino-1,2,4-triazole) are reported. The crystal structures of 1 and 6 have been solved by single-crystal X-ray diffraction, whereas the remaining compounds have been studied by means of X-ray powder diffraction methods. Compounds 1,5 are isomorphous and crystallize in the triclinic space group P1¯ with unit cell parameters for 1 of a = 5.538(1) Å, b = 7.663(1) Å, c = 7.711(2) Å, , = 62.21(1)°, , = 73.91(1)°, , = 86.11(1)°, and Z = 1. The crystal structures are comprised of one-dimensional linear chains in which the trans -[M(4atr)2]2+ units are sequentially bridged by bis(bidentate) oxalato ligands, resulting in an octahedral O4N2 donor set. Cryomagnetic susceptibility measurements show the occurrence of antiferromagnetic intrachain interactions for 2, 3, and 5, whereas compound 1 exhibits a weak ferromagnetic coupling in agreement with the out-of-plane exchange pathway involved. The magnetic behavior of 1 and 2 is analyzed and discussed in the light of the available magneto-structural data for analogous systems. CdII complex crystallizes in the monoclinic space group C2/c with unit cell parameters of a = 16.128(2) Å, b = 6.757(1) Å, c = 11.580(2) Å, , = 104.46(1)°, and Z = 4. Its crystal structure contains one-dimensional chains in which metal centers are heptacoodinated to four oxygen atoms from two symmetry-related bis(bidentate) oxalato bridges, two endocyclic nitrogen atoms of trans -coordinated triazole ligands and one water molecule, to give a CdO4OwN2 pentagonal-bipyramidal geometry. Thermoanalytical and variable-temperature X-ray powder diffraction analyzes show that compound 6 undergoes a reversible dehydration,hydration process in which the anhydrous residue crystallizes with a different crystal lattice retaining the dimensionality of the oxalato,metal framework. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Non-Covalent Aggregation of Discrete Metallo-Supramolecular Helicates into Higher Assemblies by Aromatic Pathways: Structural and Chemical Studies of New Aniline-Based Neutral Metal(II) DihelicatesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 17 2005Miguel Vázquez Abstract Neutral manganese(II), iron(II), cobalt(II), nickel(II), zinc(II) and cadmium(II) complexes with an N -tosyl-substituted N4 -donor Schiff base containing a 4,4'-methylenedianiline residue as spacer [H2La: N,N' -bis(2-tosylaminobenzylidene)-4,4'-methylenedianiline], and the zinc(II) complex with an analogous ligand [H2Lb: N,N' -bis(2-tosylaminobenzylidene)-4,4'-oxodianiline] have been prepared by an electrochemical procedure. FAB and ESI mass spectra of the complexes show peaks due to species corresponding to a general formula [M2(La,b)2 + H]+, thereby suggesting their dinuclear nature. A detailed study of the crystal packing in the unit cell of the zinc(II) complex with H2La shows that the helicates aggregate to form discrete prismatic moieties containing three molecules held together by ,,, and ,,, interactions. Moreover, the ZnII neutral dihelicate with H2Lb forms a 3D network in the solid state due to intermolecular ,-stacking interactions. 1H NMR studies of the diamagnetic compounds reported herein have been performed. Finally, the ligand H2La and its ZnII and CdII complexes have been studied by spectrophotometric and spectrofluorimetric techniques in order to get a better understanding of the formation mechanisms of the complexes and of the nature of their fluorescence emission. Emission studies show that the ZnII and CdII dihelicates with H2La display a green fluorescence in acetonitrile solution (, = 473 nm, , = 0.03 and , = 476 nm, , = 0.01, respectively). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Synthesis, Structure and Spectroscopic Properties of Novel9,10-Bis{[6-(diphenylphosphanyl)-2-pyridylmethyl]propylaminomethyl}anthracene-Bridged Group 11 Metal (M = CuI and AgI) Dinuclear ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2005Hu Xu Abstract Dinuclear complexes [M2(,-BPNNAn)]X2 (M = CuI, X = ClO4,1, X = BF4,2; M = AgI, X = BF4,3, X = ClO4,4) have been prepared by treating 9,10-bis{[6-(diphenylphosphanyl)-2-pyridylmethyl]propylaminomethyl}anthracene (BPNNAn) with M(CH3CN)4X in CH2Cl2. The structures of complexes 1, 2 and 3 have been determined by single-crystal X-ray diffraction studies. In the complexes, BPNNAn acts as a chelating ligand and two metal ions riding on two bridgehead carbon atoms in the anthracene group leads to the deformation of the anthracenyl ring. The Cu,Arene charge transfer interaction is observed from the nonfluorescent emission of Cu complex 1, while the Ag complex 3 exhibits dual emission at high concentrations in a CH2Cl2 solution. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] First-Row Transition Metal Bis(amidinate) Complexes; Planar Four-Coordination of FeII Enforced by Sterically Demanding Aryl SubstituentsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2005Christian A. Nijhuis Abstract The sterically hindered benzamidinate ligand [PhC(NAr)2], (Ar = 2,6- iPr2C6H3) has been employed to prepare bis(amidinate) complexes [{PhC(NAr)2}2M] of the divalent first-row transition metals Cr,Ni (1,5). For Cr (planar), Mn and Co (tetrahedral) the observed structures follow the electronic preference for the metal ion in its highest spin multiplicity, as determined by DFT calculations. Remarkably, the Fe derivative adopts a distorted planar structure while retaining the high-spin (S = 2) configuration. This rare combination is due to reduced interligand steric interactions in the planar vs. the tetrahedral structure, combined with a relatively small electronic preference of FeII for the tetrahedral environment. Thus, the simple bidentate ligand N,N' -diarylbenzamidinate provides a convenient means to make this unusual species accessible for further study. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] [CuI(im)],: Is this Air-Stable Copper(I) Imidazolate (8210)-Net Polymer the Species Responsible for the Corrosion-Inhibiting Properties of Imidazole with Copper Metal?EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2004Yun-Qi Tian Abstract An air-stable two-dimensional (2D) copper(I) imidazolate polymer, [CuI(im)], (1), with a d10 -d10 interaction, was synthesized solvothermally and structurally characterized by X-ray crystallography: a = 8.069(2), b = 8.068(2), c = 13.425(3) Å, , = 99.414(3)°, monoclinic, C2/c. This is the first example of an air-stable copper(I) imidazolate polymer that may play a significant role in the corrosion-inhibition mechanism of imidazole (or its derivatives) with copper metal. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Bulk Nanoporous Metal for ActuationADVANCED ENGINEERING MATERIALS, Issue 8 2010Hai-Jun Jin Abstract Nanoporous metals prepared by controlled chemical or electrochemical corrosion of alloys can provide prototypical manifestations of bulk nanostructured material. Samples are readily prepared with dimensions at the millimeter or centimeter scale, while at the same time the microstructure is a homogeneous array of interpenetrating solid skeleton phase and pore channels with a characteristic size that can reach down to below 5,nm. The interest in nanoporous metals as functional materials derives from recent observations of unique materials behavior resulting from their extremely small structure size and their open porosity with large volume-specific surface area. As an example, this article discusses the possible use of nanoporous metal for actuation. [source] Cost-Efficient Metal,Ceramic Composites,Novel Foam-Preforms, Casting Processes and Characterisation,ADVANCED ENGINEERING MATERIALS, Issue 3 2010Gisela Standke Because of their dissatisfactory cost-performance ratio metal matrix composites (MMCs) are still not established in industry, although they show improved properties compared to pure metals in some application fields. The present paper describes the development of enhanced MMCs based on silicon carbide (SiC) foams made by the Schwartzwalder process. Therefore, foams with cell sizes of 30, 45 and 60,ppi based on pressure less sintered SiC (SSiC) were developed. They were coated with layers of coarse SiC particles, which form a rough strut surface. The ceramic content of the foams could be increased to values of 20,30,mass%. Additionally, foam preforms based on clay-bonded SiC (as they are known from molten metal infiltration) were tested. The preforms were infiltrated with aluminium alloys AlSi9Cu3 and AlSi7Mg0.6 and cast iron EN-GJSA-XNiCr35-5-2 and EN-GJL-250. For aluminium alloys high pressure die casting (HPC) as well as gravity casting was applied, whereas iron was only infiltrated by gravity casting. For HPC an excellent interlocking of metal and preform was observed because of the microporosity of the rough surface of the SSiC foam struts. By the use of gravity casting preform cells up to 45,ppi could be well infiltrated. Microporosity in the ceramic coating and the typical hollow struts of the foams did not show metal infiltration. Even by use of moderate ceramic volume fractions pressure-infiltrated aluminium matrix composites showed a high specific stiffness of up to E/,,=,42,GPa,cm3,g,1 compared to conventional Al or Mg alloys (E/,,=,25,27,GPa,cm3,g,1). Ceramic foam based MMCs produced by pressure less casting showed no advantages in mechanical properties compared to pure metals. Nevertheless it can be expected that they can provide improved wear resistance and lower thermal expansion coefficients. [source] A Metal,Macrocycle Complex as a Fluorescent Sensor for Biological Phosphate Ions in Aqueous SolutionEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2010Xiao-huan Huang Abstract We synthesized tetraazamacrocycles 1 and 2 bearing two anthryl groups as sidearms, both of which exhibited high selectivity for the ZnII ion in switching-on-type responses in aqueous solution. For ligand 1, ZnII is coordinated by four nitrogen atoms of the macrocycle and two amino groups on the pendent arms, which results in proximity between the twofluorophores. So, 1 -ZnII shows obvious excimer emission in aqueous solution. When PPi or ATP was added (pH 7.4), the excimer emission of 1 -ZnII was quenched, whereas monomer emission was revived. To the best of our knowledge, no other known sensor has this characteristic under physiological pH conditions. At the same time, the obvious different fluorescence response of 1 -ZnII for PPi and ATP in water shows that receptor 1 -ZnII can be used as a selective fluorescent chemosensor for PPi and ATP anions. [source] A Feasibility Study of Wire-Woven Cellular Metal as Catalytic Support Material,ADVANCED ENGINEERING MATERIALS, Issue 7 2009Byung-Chul Choi Wire-woven bulk Kagome (WBK) specimens were fabricated by wires made of Fecralloy, a Fe-Cr-Al alloy, and their feasibility as supports for an oxidation catalyst was investigated. For catalytic reactivity, the catalyst-coated WBK supports perform as well as the corresponding cordierite support, even though the WBK support has much lower flow resistance. Moreover, WBK is advantageous in terms of mass productivity, weight, durability and impact strength. The image shows a close-up view of the WBK support after heat treatment. [source] Crystal Growth of the Metal,Organic Framework Cu3(BTC)2 on the Surface of Pulp FibersADVANCED ENGINEERING MATERIALS, Issue 1-2 2009Pia Küsgens In situ growth of highly porous metal,organic frameworks (MOFs) in the presence of pulp fibers results in high surface area MOF/textile composites. Such a carrier concept is indispensable for any industrial application of MOFs. [source] Ultrasonically Welded Aluminium Foams/Sheet Metal , Joints,ADVANCED ENGINEERING MATERIALS, Issue 9 2006C. Born Abstract The ultrasonic welding technology enables to produce high-strength joints between sheet metal and aluminium foam sandwich (AFS) without melting of the metal or any damage of the foam structure. In the investigations the used welding processes and different factors influencing the weldability were varied. The achievable mechanical properties for ultrasonically welded metal joints, especially under monotonic and cyclic load, will be discussed. Additionally, results of microscopic investigations of the bonding zone and possible applications are presented. [source] The Role of Binder Content on Microstructure and Properties of a Cu-base Active Brazing Filler Metal for Diamond and cBNADVANCED ENGINEERING MATERIALS, Issue 5 2005R. Elsener Melting experiments of Cu-Sn-Ti-Zr filler metal powder containing cellulose nitrate and graphite, respectively, resulted in the formation of nanosized TiC particles in both Cu-rich phase and CuSn3Ti5 intermetallic regions of the alloy (see figure). The variation of the binder type and content allows to tailor the properties of the filler metals in terms of erosion resistance, decisive for a new generation of superabrasive tools. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||