Search results for "Ordination"
showing 10 items of 1367 documents
Anion coordination chemistry in aqueous solution of polyammonium receptors
2006
The behavior of polyamines as receptors of selected families of anions in water is explored. First metallocyanide interaction with saturated polyammonium hosts is analyzed both in solution and in the solid state. The utility of potentiometry, multinuclear NMR, microcalorimetry and cyclic voltammetry to describe solution features of this chemistry is described for selected systems. Sulfate, phosphate, polyphosphate and nucleotide interactions with large polyammonium receptors are then reviewed. Hydrogen bond formation is discussed from a thermodynamic point of view. The influence of the presence of aromatic fragments within the structure on the binding strength is discussed. Factors affectin…
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…
Sublimable Single Ion Magnets Based on Lanthanoid Quinolinate Complexes: The Role of Intermolecular Interactions on Their Thermal Stability
2018
We report the design, preparation, and characterization of two families of thermally robust coordination complexes based on lanthanoid quinolinate compounds: [Ln(5,7-Br2q)4]− and [Ln(5,7-ClIq)4]−, where q = 8-hydroquinolinate anion and Ln = DyIII, TbIII, ErIII, and HoIII. The sodium salt of [Dy(5,7-Br2q)4]− decomposes upon sublimation, whereas the sodium salt of [Dy(5,7- ClIq)4]−, which displays subtly different crystalline interactions, is sublimable under gentle conditions. The resulting film presents low roughness with high coverage, and the molecular integrity of the coordination complex is verified through AFM, MALDI-TOF, FT-IR, and microanalysis. Crucially, the single-molecule magnet …
Coordination Chemistry in the Solid: Evidence for Coordination Modes within Hybrid Materials Different from those in Solution
2002
Two routes of incorporation of europium(III) salts into cyclam-containing hybrid materials have been explored, to elucidate the coordination mode of EuIII in cyclam-containing hybrid materials in a study of the arrangement of cyclam moieties during the solgel process. They were 1) complexation of europium salts by N-tetrasubstituted 1,4,8,11-tetraazacyclotetradecane (cyclam) derivatives bearing four hydrolysable Si(OEt)3 groups, followed by hydrolysis and polycondensation of these complexes; and 2) hydrolysis and polycondensation of N-tetrasubstituted silylated cyclam derivatives, then incorporation of europium salts directly into the hybrid materials. The coordination mode of europium salt…
PCP-bridged chalcogen-centred anions: coordination chemistry and carbon-based reactivity.
2012
Since the discovery of the stabilising influence of thiophosphinoyl groups in methanediides by Le Floch et al. (Angew. Chem. Int. Ed., 2004, 43, 6382), numerous transition metal, lanthanide and actinide complexes of bis(thiophosphinoyl) carbene ligands have been investigated with an emphasis on the electronic structure and reactivity of the metal–carbon bonds. This Perspective begins by discussing main group (s- and p-block) complexes of this ligand and draws attention to differences compared to their d and f-block analogues. Investigations targeting the heavy chalcogen analogues of the Le Floch ligand have revealed an unusual carbon-based reactivity that led to the discovery of novel multi…
Slow magnetic relaxation in a hydrogen-bonded 2D array of mononuclear dysprosium(III) oxamates.
2013
The reaction of N-(2,6-dimethylphenyl)oxamic acid with dysprosium(III) ions in a controlled basic media afforded the first example of a mononuclear lanthanide oxamate complex exhibiting a field-induced slow magnetic relaxation behavior typical of single-ion magnets (SIMs). The hydrogen-bond-mediated self-assembly of this new bifunctional dysprosium(III) SIM in the solid state provides a unique example of 2D hydrogen-bonded polymer with a herringbone net topology.
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…
Spin state switching in iron coordination compounds
2013
The article deals with coordination compounds of iron(II) that may exhibit thermally induced spin transition, known as spin crossover, depending on the nature of the coordinating ligand sphere. Spin transition in such compounds also occurs under pressure and irradiation with light. The spin states involved have different magnetic and optical properties suitable for their detection and characterization. Spin crossover compounds, though known for more than eight decades, have become most attractive in recent years and are extensively studied by chemists and physicists. The switching properties make such materials potential candidates for practical applications in thermal and pressure sensors …
Discrete unusual mixed-bridged trinuclear CoIII2CoII and pentanuclear NiII coordination complexes supported by a phenolate-based ligand: theoretical …
2021
Two new complexes [CoIII2CoII(μ-OL)2(μ-OOCCH3)2(μ-N3)2(N3)2]·Et2O (1·Et2O) and [NiII5(μ-OL)4(μ-OOCCH3)2(OOCCH3)2(μ-N3)2]·CH3CN (2) (HOL = 2-((2-(pyridin-2-yl)ethylamino)methyl)phenol) have been synthesized and characterized by elemental analysis, IR, and UV/Vis spectroscopy. Structural analysis revealed that 1 is a discrete trinuclear and 2 is a discrete pentanuclear coordination complex. In complex 1, terminal metal (CoIII) is in a distorted octahedral MN4O2 environment where coordination is satisfied by two nitrogen atoms and one oxygen atom of the ligand, and an oxygen atom from the acetate group and two nitrogen atoms from azide (one each from the bridging and terminal ones). The centra…