Search results for "Geometry"
showing 10 items of 4487 documents
An Unusual Geometry of Five-Coordinate Copper(II): The Structure of Cu(terpy)I2 and Spectroscopic Investigations of Complexes Cu(terpy)X2 (X: I, NCS)
1991
The structure of the compound Cu(terpy)I2 (terpy 2,2′: 6′, 2″ terpyridine) was determined at room temperature. It is monoclinic, space group I2/c with a = 13.689(3), b = 9.510(2), c = 11.605(3) Å, β = 97.59(4)° and Ζ = 4. The copper(II) ions are five-coordinated by the three nitrogen atoms from the terpy ligand and the two iodine atoms. The CuN3I2 polyhedron exhibits the same unusual “reverse” geometry as is observed for Cu(terpy)(NCS)2. Single crystal EPR measurements of the iodide and the isothio-cyanate complexes confirmed the structural results, excluding the possibility of a dynamically averaged geometry.
Exchange coupling in a thiocyanato-bridged copper(II) chain: Computational approach to magnetostructural correlations
2021
Abstract In this article we report the synthesis and magneto-structural characterization of two new copper(II) compounds with thiocyanato and methyl(2-pyridil) ketone oxime (mpkOH), namely [Cu(NCS)(mpkO)(mpkOH)] (1) and [Cu(µ-NCS)(NCS)(mpkOH)]n (2). Compound 1 is a mononuclear complex that crystallizes as discrete units. Conversely, compound 2 is a single equatorial-axial end-to-end thiocyanato bridged polymeric chain of Cu(II) with the oxime as a co-ligand. The coordination geometry around the Cu(II) centers is distorted square pyramidal for 1 and 2. The magnetic susceptibility data for 2 reveal weak intrachain antiferromagnetic coupling, with J value −0.74(3) cm−1 and g = 2.10(1). The ap…
Synthesis and Structural Study of Tetravalent (Zr 4+ , Hf 4+ , Ce 4+ , Th 4+ , U 4+ ) Metal Complexes with Cyclic Hydroxamic Acids
2015
Six- and seven-membered cyclic hydroxamic acids, such as 1-hydroxypiperidine-2-one (1H, 1,2-PIPOH) and 1-hydroxyazepan-2-one (2H), have recently been identified in some mixed siderophores as one of their three chelating subunits. Compared to their ubiquitous noncyclic counterparts, cyclic hydroxamates are preorganized for metal binding. Surprisingly, the coordination chemistry of these bidentate, monoanionic ligands remains virtually unknown, even in the case of iron(III). We report herein the first structural study of the complexes of 1– and of 6–, an unsaturated seven-membered ring analog of 2–, with tetravalent cations of transition metals (zirconium and hafnium), lanthanide (cerium), an…
Synthesis, crystal structure and properties of two acetazolamide (5-acetamido-1,3,4-thiadiazole-2-sulfonamide) complexes: bis(5-acetamidato- 1,3,4-th…
1992
Abstract The diverse coordination chemistry exhibited by acetazolamide (H2acm), a potent inhibitor of the carbonic anhydrase metalloenzyme, is highlighted in two new copper(II) complexes of this ligand: [Cu(Hacm)2(en)2] (I) and [Cu(Hacm)2(tn)2] (II). The synthesis, crystal structure and spectroscopic properties of both compounds are reported in this paper. The structures of both compounds consist of discrete units of [Cu(Hacm)2(en)2] (I) and [Cu(Hacm)2(tn)2] (II), respectively, interacting through van der Waals contacts and hydrogen bonds only. Hacm, however, binds differently in each compound. In both cases, the Cu(II) ions, lying on the symmetry centers, show an elongated octahedral geome…
Alkyl Complexes of Rare-Earth Metals That Contain a Furyl-Functionalized Cyclopentadienyl Ligand: Alkyl Cation Formation and Unexpected Ring-Opening…
2003
Rare-earth metal complexes of the type [Ln{η5:η1-C5Me4SiMe2(C4H3O-2)}(CH2SiMe3)2(THF)] (Ln = Y, Lu) were prepared by σ-bond metathesis of [Ln(CH2SiMe3)3(THF)2] with the 2-furyl-functionalized tetramethylcyclopentadiene (C5Me4H)SiMe2(C4H3O-2) and isolated as colorless crystals. Single-crystal X-ray structure analysis of the lutetium complex confirmed the coordination of the furyl group and THF to give a molecule of trigonal bipyramidal geometry with the oxygen donor atoms in the apical positions. The lability of the oxygen donor atoms results in fluxional behavior. Reaction with triphenylborane in THF gave thermally robust mono(alkyl) cations [Ln{η5:η1-C5Me4SiMe2(C4H3O-2)}(CH2SiMe3)(THF)n]+.…
Studies on the antitumor activity of complexes of R2Sn(IV) with penicillamine enantiomers and with 3-thio-propanoic acid, and correlation with struct…
1990
Abstract The activity of diorganotin(IV) derivatives, with SnS bonds, against murine leukemia P-388, has been investigated. The water-soluble penicillamine (PenH2) complexes, Me2Sn(D-Pen), Me2Sn(L-Pen), Me2Sn(D-PenH)2 and Me2Sn(L-PenH)2, are essentially inactive, and do not show any dependence of the antitumor activity from the configuration about the chiral centre. The complexes with 3-thiopropanoic acid (H2Tpr), R2Sn(Tpr), are active for REt and Ph, in line with the general behaviour of R2Sn(IV) derivatives. The nature of the organotins in the vehicle of administration is investigated by 119Sn Mossbauer spectroscopy. The structures of solid state polymers, occurring in suspensions, are …
Genotoxic Potential of N ‐(Benzothiazolyl)sulfonamide Copper(II) Complexes on Yeast Cells Transformed with YEGFP Expression Constructs Containing the…
2006
Four ternary complexes [Cu(L)2(phen)] where L is an N(benzothiazol-2-yl)sulfonamide derivative have been prepared and their ability to cleave DNA has been studied. The complexes were structurally characterized with the aid of single-crystal X-ray crystallography. Whereas the molecular structure of the [Cu(L1)2(phen)] (1) [HL1 = N-(6-chlorobenzothiazol-2-yl)benzenesulfonamide] and [Cu(L3)2(phen)] (3) [HL3 = N-(benzothiazol-2-yl)benzenesulfonamide] complexes can best be described as having a distorted squareplanar geometry, that of the [Cu(L4)2(phen)] (4) [HL4 = N(benzothiazol-2-yl)toluenesulfonamide] complex shows a strictly square-planar geometry. The [Cu(L2)2(phen)MeOH] (2) [HL2 = N-(6-chl…
Strong protective action of Copper(II) N-substituted sulfonamide complexes against reactive oxygen species.
2004
Copper(II) complexes of N -benzothiazolsulfonamides, [Cu( N -2-(5,6-dimethylbenzothiazole)toluenesulfonamidate) 2 (dmso) 2 ] ( 1 ), [Cu( N -2-(6-chlorobenzothiazole)benzenesulfonamidate) 2 (dmso) 2 ] ( 2 ) and [Cu( N -2-(6-chlorobenzothiazole)toluenesulfonamidate) 2 (dmso) 2 ] ( 3 ) with interesting protective properties against superoxide radicals have been prepared. The compounds have been characterized by X-ray diffraction and their chemical properties have been studied by spectroscopic methods. The crystal structure of 1 shows that the copper(II) is surrounded by two benzothiazole N atoms from the sulfonamide ligands and two O atoms from the dimethylsulfoxide molecules in a square plana…
Tuning of interfacial charge transport in polyporphine/phthalocyanine heterojunctions by molecular geometry control for an efficient gas sensor
2022
Abstract Owing to high interfacial conductivity, organic heterostructures hold great promises to augment the electrical performances of electronic devices. In this endeavor, the present work reports fabrication of novel polyporphine/phthalocyanine heterostructures and investigates the modulation of charge transport induced by structural change of polyporphine and its implication on ammonia sensing properties. Polyporphines materials are electrosynthesized by oxidation of zinc(II) porphine monomer that corresponds to the fully unsubstituted porphyrin. At less-positive anodic potential, low conducting meso,meso-singly-linked type-1 polymer (pZnP-1) is formed in which a monomer unit stays orth…
Perimeter leakage current in polymer light emitting diodes
2009
Observation of leakage current paths through the device perimeter in standard poly(phenylene vinylene)-based light-emitting devices is reported. Perimeter leakage currents govern the diode performance in reverse and low positive bias and exhibit an ohmic character. Current density correlates with the perimeter-to-area ratio thus indicating that leakage currents are mainly confined on polymer regions in the vicinity of metallic contact limits (device perimeter). © 2008 Elsevier B.V. All rights reserved.