Search results for "Paramagnetic"
showing 10 items of 600 documents
Zinc complexation to N-substituted sulfonamide ligands. Preparation, properties and crystal structure of copper(II) doped ?[Zn(sulfamethizolate)2(py)…
2003
Abstract The single crystal structure and spectroscopic properties of the copper(II) doped {[Zn(sulfamethizolate) 2 (py)]·H 2 O} ∞ are reported. The complex is a polymer where the Zn(II) ions are coordinated by four N atoms in a very distorted tetrahedral environment. The sulfamethizolate anion acts as a monodentate ligand through the thiadiazole N atom and as a bridging ligand via the amino and thiadiazole N atoms. The compound is studied by EPR, by 13 C NMR in solid state and by 1 H and 13 C NMR in DMSO-d 6 solution. The similarity between the 13 C NMR spectrum in solution and the solid 13 C NMR spectrum indicates that the structure of the compound remains in solution. The EPR spectrum sh…
Synthesis, Crystal Structures and Properties of [Cu(L1)2(py)2(H2O)](H2O) [HL1 = N-(5-ethyl-[1,3,4]–thiadiazole-2-yl)-toluenesulfonamidate] and [Cu(L2…
2007
A series of new N-sulfonamidate ligands and their cooper(II) complexes, [Cu(N-(5-ethyl-[1,3,4]-thiadiazole-2-yl)-toluenesulfonamidate)2(py)2(H2O)](H2O) (1) and [Cu(N-(5-ethyl-[1,3,4]-thiadiazole-2-yl)-benzenesulfonamidate)2(py)2(H2O)] (2) have been synthesized and characterized. The X-ray crystal structures of the complexes 1 and 2 have been determined. In the both two complexes, the Cu2+ ion is five-coordinated, forming a CuN4O chromophore. The ligands act as monodentate, coordinating the metal ion through a single Nthiadiazole atom. The molecules from the reaction medium (pyridine and water) also participate to the coordination of Cu2+ ion as monodentate ligands. Both two complexes have a…
Cyanido‐Bearing Cobalt(II/III) Metalloligands – Synthesis, Crystal Structure, and Magnetic Properties
2014
New examples of cyanido-bearing cobalt(III/II) complexes have been obtained by treatment of CoCl2·6H2O with bidentate nitrogen donors and potassium cyanide in a methanol/water mixture. Depending on the chelating ligand, the cobalt(III) complexes PPh4[Co(en)(CN)4] (1, en = ethylenediamine), PPh4[Co(ampy)(CN)4]·1.5H2O [2, ampy = 2-(aminomethyl)pyridine], and PPh4[Co(phen)(CN)4]·CH3OH·0.25H2O (3, phen = 1,10-phenanthroline) and the cobalt(II) complex PPh4[Co(dmphen)(CN)3]·3H2O (4, dmphen = 2,9-dimethyl-1,10-phenanthroline) were obtained. The complexes were characterized by single-crystal X-ray diffraction and variable-temperature magnetic measurements. They are all mononuclear species with six…
Structure, spectroscopic and magnetic properties of a novel 1-D coordination copper(II) polymer containing BIMAM ligand [BIMAM=bis(imidazol-2-yl)meth…
2006
Abstract This paper reports the synthesis and complete characterization (structural, spectroscopic and magnetic) of [Cu(HBIMAM)Cl(C4O4)]n · (H2O)n [BIMAM = bis(imidazol-2-yl)methylaminomethane]. This compound is made of infinite chains – running along c axis – built from [CuCl(HBIMAM)]+ units bridged together by μ-O1,O3-bis(monodentate) squarate anions. Non-covalent interactions (H-bonds and π–π) drive the build-up of an infinite three-dimensional array. The coordination polyhedron about the copper(II) ion is distorted square pyramidal. The EPR spectrum is indicative of a d z 2 - y 2 ground state for the Cu(II) ions with significant contribution of d z 2 . Magnetic susceptibility measuremen…
Field-induced single ion magnet behaviour of discrete and one-dimensional complexes containing [bis(1-methylimidazol-2-yl)ketone]-cobalt(II) building…
2021
International audience; We describe herein the first examples of six-coordinate CoII single-ion magnets (SIMs) based on the β-diimine Mebik ligand [Mebik = bis(1-methylimidazol-2-yl)ketone]: two mononuclear [CoII(Rbik)2L2] complexes and one mixed-valence {CoIII2CoII}n chain of formulas [CoII(Mebik)(H2O)(dmso)(μ-NC)2CoIII2(μ-2,5-dpp)(CN)6]n·1.4nH2O (3) [L = NCS (1), NCSe (2) and 2,5-dpp = 2,5-bis(2-pyridyl)pyrazine (3)]. Two bidentate Mebik molecules plus two monodentate N-coordinated pseudohalide groups in cis positions build somewhat distorted octahedral surroundings around the high-spin cobalt(II) ions in 1 and 2. The diamagnetic [CoIII2(μ-2,5-dpp)(CN)8]2− metalloligand coordinates the pa…
Field-Induced Slow Magnetic Relaxation in a Mononuclear Manganese(III)-Porphyrin Complex
2015
We report on a novel manganese(III)-porphyrin complex with the formula [Mn(III) (TPP)(3,5-Me2 pyNO)2 ]ClO4 ⋅CH3 CN (2; 3,5-Me2 pyNO=3,5-dimethylpyridine N-oxide, H2 TPP=5,10,15,20-tetraphenylporphyrin), in which the Mn(III) ion is six-coordinate with two monodentate 3,5-Me2 pyNO molecules and a tetradentate TPP ligand to build a tetragonally elongated octahedral geometry. The environment in 2 is responsible for the large and negative axial zero-field splitting (D=-3.8 cm(-1) ), low rhombicity (E/|D|=0.04) of the high-spin Mn(III) ion, and, ultimately, for the observation of slow magnetic-relaxation effects (Ea =15.5 cm(-1) at H=1000 G) in this rare example of a manganese-based single-ion ma…
Bis‐μ‐pyrazolate‐Bridged Dinickel(II) and Dicopper(II) Complexes: An Example of Stereoelectronic Preference of Metal Ions and Stabilization of Mixed‐…
2007
New dimeric nickel(II) and copper(II) complexes [(L)Ni(μ-L′)]2[ClO4]21 and [(L)Cu(μ-L′)]2[ClO4]22, [2-[3-(2′-pyridyl)pyrazol-1-ylmethyl]pyridine (L) and 3-(2-pyridyl)pyrazole (HL′)] have been synthesized, structurally characterized, and their absorption, magnetic, EPR and redox properties investigated. The crystal structure of 1·MeCN reveals a planar {Ni2(μ-L′)2}2+ core [Ni···Ni separation: 4.0765(10) A] in which each distorted octahedral NiII ions is terminally coordinated by a tridentate ligand L and bridged by two HL′ units, in their deprotonated form. The structural analysis of 2·2MeCN reveals two five-coordinate CuII ions, each terminally coordinated by adopting only a bidentate coordi…
Countercomplementarity and Strong Ferromagnetic Coupling in a Linear Mixed μ-Acetato, μ-Hydroxo Trinuclear Copper(II) Complex. Synthesis, Structure, …
2001
The structural and magnetic data of the trinuclear compound [Cu3(L)2(CH3COO)2(OH)2(dmf)2] (HL = N-(2-methylpyridyl)toluensulfonylamide) are reported. The compound crystallizes in the monoclinic system, space group P2(1)/n (no. 14), with a = 11.6482(6) A, b = 13.5772(6) A, c = 13.5306(7) A, alpha = 90 degrees, beta = 92.859(5) degrees, gamma = 90 degrees, and Z = 2. The three copper atoms form an exact linear arrangement. Neighboring coppers are connected by a hydroxo bridge and a bidentate syn-syn carboxylato group. The coordination spheres of the terminal copper atoms are square pyramidal with a dmf molecule as the apical ligand. The central copper has a regular square planar geometry. The…
Pulsed EPR determination of water accessibility to spin-labeled amino acid residues in LHCIIb.
2009
Membrane proteins reside in a structured environment in which some of their residues are accessible to water, some are in contact with alkyl chains of lipid molecules, and some are buried in the protein. Water accessibility of residues may change during folding or function-related structural dynamics. Several techniques based on the combination of pulsed electron paramagnetic resonance (EPR) with site-directed spin labeling can be used to quantify such water accessibility. Accessibility parameters for different residues in major plant light-harvesting complex IIb are determined by electron spin echo envelope modulation spectroscopy in the presence of deuterated water, deuterium contrast in …
Trinuclear N,N-Bridged Copper(II) Complexes Involving a Cu3OH Core: [Cu3(μ3-OH)L3A(H2O)2]A·(H2O)x {L = 3-Acetylamino-1,2,4-triazolate; A = CF3SO3, N…
2000
The reaction of Haat [Haat = (3-acetylamino-1,2,4-triazole)] with aquated Cu(CF3SO3)2, Cu(NO3)2, and Cu(ClO4)2, respectively, in water results in the trinuclear complexes [Cu3(OH)(aat)3(CF3SO3)(H2O)2](CF3SO3) (1), [Cu3(OH)(aat)3(NO3)(H2O)2](NO3).(H2O)2 (2), and [Cu3(OH)(aat)3(ClO4)(H2O)2](ClO4) (3). The synthesis, X-ray structure, and magnetic and spectroscopic properties of the three title complexes are described. The cation of the three complexes is trinuclear with a Cu3OH skeleton which has the N-N diazine grouping of a triazole ring as bridge between each pair of copper atoms. The Cu3OH units have an average Cu-O distance of 1.991(6) (1), 2.000(6) (2), and 2.007(6) (3) A, an average Cu-…