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Design of single chain magnets through cyanide-bearing six-coordinate complexes
2005
Abstract The design and preparation of stable cyanide-bearing six-coordinate complexes of formula [MIII(L)(CN)x](x + l − m)− (M = trivalent transition metal ion and L = polydentate blocking ligand) are summarized here. Their use as ligands towards either fully hydrated metal ions or coordinatively unsaturated preformed species, to afford a wide variety of low-dimensional metal assemblies whose nuclearity, dimensionality and magnetic properties can be tuned, is also reviewed. Special emphasis is put on the appropriate choice of the end-cap ligand L whose denticity determines the number of coordinated cyanide groups in the mononuclear precursors. Among the different new spin topologies obtain…
[Cr(dmbipy)(ox)2]−: a new bis-oxalato building block for metal assembling. Crystal structures and magnetic properties of XPh4[Cr(dmbipy)(ox)2]·5H2O (…
2010
The synthesis, X-ray structure and variable-temperature magnetic study of new compounds of formula PPh4[Cr(dmbipy)(ox)2]·5H2O (1), AsPh4[Cr(dmbipy)(ox)2]·5H2O (2), {Ba(H2O)2[Cr(dmbipy)(ox)2]2}n·17/2nH2O (3) and {Ag(H2O)[Cr(dmbipy)(ox)2]}n·3nH2O (4) (PPh4+ = tetraphenylphosphonium cation; AsPh4+ = tetraphenylarsonium cation; dmbipy = 4,4′-dimethyl-2,2′-bipyridine; ox2− = oxalate dianion) are reported herein. The isomorphous compounds 1 and 2 are made up of discrete [Cr(dmbipy)(ox)2]− anions, XPh4+ cations [X = P (1) and As (2)] and uncoordinated water molecules. The chromium environment in 1 and 2 is distorted octahedral with Cr–O and Cr–N bond distances varying in the ranges 1.950(2)–1.9782…
Synthesis and ROMP activity of aminophenol-substituted tungsten(VI) and molybdenum(VI) complexes
2008
Abstract Tungsten(VI) and molybdenum(VI) complexes [MO(L1)Cl2] and [M(X)(L2)Cl3] (X = O, NPh) with tridentate aminobis(phenolate) ligand L1 = methylamino-N,N-bis(2-methylene-4,6-dimethylphenolate) and bidentate aminophenolate ligand L2 = 2,4-di-tert-butyl-6-((dimethylamino)methyl)phenolate) were prepared and characterised. These complexes are principally stable in open atmosphere under ambient conditions. When activated with Et2AlCl, they exhibited high activity in ring-opening metathesis polymerisation (ROMP) of 2-norbornene (NBE) and its derivatives. Especially complexes [M(NPh)(L2)Cl3], which are easily available from corresponding metal oxides MO3 by a simple three-step synthesis, were …
Metal-organic coordination frameworks based on mixed methylmalonate and 4,4′-bipiridine ligands: synthesis, crystal structure and magnetic properties
2010
Five new complexes of formulae [M2(4,4′-bpy)(Memal)2X2]n [M = Fe(III) (2), Mn(II) (3), Co(II) (4), Ni(II) (5) and Zn(II) (6), and X = Cl−/OH− (2) and H2O (3–6); 4,4′-bpy = 4,4′-bipyridine and Memal = methylmalonate dianion] have been synthesized by following the previously reported procedure for [Cu2(4,4′-bpy)(Memal)2(H2O)2]n (1). Moreover, two new phases of the Cu(II)/Memal/4,4′-bpy system, namely {[Cu(4,4′-bpy)2][Cu(4,4′-bpy)2(Memal)(NO3)(H2O)]}n·nNO3·3.5nH2O (7) and [Cu(4,4′-bpy)2(Memal)(H2O)]n·nH2O (8), were obtained by varying the synthetic conditions. They were all structurally characterized by single crystal X-ray diffraction, and the magnetic properties of 2–5, 7 and 8 were investig…
Inverted molecular cups: 1-D and 2-D Ag(I) coordination polymers from resorcinarene bis-thiacrowns
2016
Resorcinarene bis-thiacrown hosts 1–3 were prepared and crystallized with silver trifluoroacetate yielding one and two dimensional Ag coordination polymers. The complexation of silver in exo-cavity fashion folds the thiacrown bridges inwards transforming the resorcinarene hosts into inverted molecular cups. The silver cations were coordinated to the resorcinarene ligands and trifluoroacetate anions, which act as monodentate or bidendate bridging ligands between the metal ions. Argentophilic Ag⋯Ag (2.93–3.38 A) interactions supported by two bridging carboxylate anions were found in two of the structures, whereas longer Ag⋯Ag distances were observed if only one anion connected the silver cati…
Effects of preorganization in the chelation of UO22+ by hydroxamate ligands: cyclic PIPO– vs linear NMA–
2018
International audience; Many siderophores incorporate as bidentate chelating subunits linear and more seldomly cyclic hydroxamate groups. In this work, a comparative study of the uranyl binding properties in aqueous solution of two monohydroxamic acids, the prototypical linear N-methylacetohydroxamic acid (NMAH) and the cyclic analog 1-hydroxypiperidine-2-one (PIPOH), has been carried out. The complex [UO2(PIPO)(2)(H2O)] crystallized from slightly acidic water solutions (pH < 5), and its molecular structure was determined by X-ray diffraction. The uranyl speciation in the presence of both ligands has been thoroughly investigated in a 0.1 M KNO3 medium at 298.2 K by the combined use of four …
Ni(II) and Zn(II) complexes with cinoxacin. Synthesis and characterization of M(Cx)2(DMSO)n(H2O)m (n=0, 2; m=2, 4). Crystal structures of [M(Cx)2(DMS…
1993
Abstract New metal complexes of cinoxacin (HCx=1-ethyl-l,4-dihydro-4-oxo(1,3)dioxolo(4,5-g)cinnoline-3-carboxylic acid) were synthesized, isolated as [Zn(Cx)2(DMSO)2]·4H2O, [Ni(Cx)2(DMSO)2]·4H2O, Zn(Cx)2·4H20 and Ni(Cx)2·2H2O, and characterized by elemental analysis, TG studies, IR and UVVis spectroscopic techniques. The crystal and molecular structures of the complexes [M(Cx)2(DMSO)2]·4H2O (M=Zn(II), Ni(II)) have been determined by X-ray structure analysis. The crystals of [Zn(Cx)2(DMSO)2]·4H2O are triclinic, space group P 1 with unit cell dimensions a=8.950(4), b=9.168(5), c=11.650(6) A, α=69.06(1), β=82.05(1), γ=75.63(1)°, V=863.6(8) A3; [Ni(Cx)2(DMSO)2]·4H20 is monoclinic, space group …
Structural properties and applications of multidentate [O,N,O,X'] aminobisphenolate metal complexies
2012
Abstract Aminobisphenols with side-arm donors are versatile tetradentate ligands that effectively coordinate to the metal ions in a tripodal fashion. Most of the metal ions form electrically neutral isolable complexes with aminobisphenolates with different side chains. However, some anionic complexes and zwitterions are also described. The coordination geometry of the metal centre can be controlled by the ligand design. Especially, the ortho -substituents of the phenolate moieties as well as the nature of side-arm donor influence the structure and reactivity of the complexes formed. Depending on the metal ion and the ligand environment, the complexes formed can be monomeric or dimeric ones.…
Trimethylplatinum(IV) complexes with ON bidentate ligands
1972
Abstract Complexes of the trimethylplatinum(IV) moiety with bidentate monobasic salicylaldimines C 6 H 5 (OH)CHNR (R = ethyl, propyl, phenyl) have been prepared and characterized by IR, UV and NMR spectra and magnetic susceptibility measurements. The complexes are dimeric with double PtOPt bridges, and the metal appears to be pseudo-octahedrally hexacoordinated.
[Fe(bipy)(CN)4]- as a Versatile Building Block for the Design of Heterometallic Systems: Synthesis, Crystal Structure, and Magnetic Properties of PP…
2002
The new cyano complexes of formulas PPh4[FeIII(bipy)(CN)4]·H2O (1), [{FeIII(bipy)(CN)4}2MII(H2O)4]·4H2O with M = Mn (2) and Zn (3), and [{FeIII(bipy)(CN)4}2ZnII]·2H2O (4) [bipy = 2,2‘-bipyridine and PPh4 = tetraphenylphosphonium cation] have been synthesized and structurally characterized. The structure of complex 1 is made up of mononuclear [Fe(bipy)(CN)4]- anions, tetraphenyphosphonium cations, and water molecules of crystallization. The iron(III) is hexacoordinated with two nitrogen atoms of a chelating bipy and four carbon atoms of four terminal cyanide groups, building a distorted octahedron around the metal atom. The structure of complexes 2 and 3 consists of neutral centrosymmetric […