Search results for " Paramagnetic resonance"
showing 10 items of 567 documents
Copper-Assisted Hemiacetal Synthesis: A Cu II Chain Obtained by a One-Step in situ Reaction of Picolinaldehyde
2014
International audience; The 1D polymer complex [Cu2(L)2(SCN)2]n (1 ) has been synthesised in a one‐step in situ reaction of picolinaldehyde with sodium thiocyanate. The complex 1 was characterised by FTIR spectroscopy, UV/Vis spectrophotometry and elemental analysis. The crystal structure of complex 1 shows that chains of dimer complexes are formed with tetra‐ and pentacoordinate copper centres alternately linked by one thiocyanato and two alkoxido bridges. Variable‐temperature magnetic measurements showed a strong antiferromagnetic interaction between the copper centres within the dimer mediated by the two alkoxido bridges with a J value of –374 cm–1, which is in agreement with the DFT‐cal…
Spectroscopic and DFT Characterization of a Highly Reactive Nonheme FeV–Oxo Intermediate
2018
The reaction of [(PyNMe3)FeII(CF3SO3)2], 1, with excess peracetic acid at −40 °C generates a highly reactive intermediate, 2b(PAA), that has the fastest rate to date for oxidizing cyclohexane by a nonheme iron species. It exhibits an intense 490 nm chromophore associated with an S = 1/2 EPR signal having g-values at 2.07, 2.01, and 1.94. This species was shown to be in a fast equilibrium with a second S = 1/2 species, 2a(PAA), assigned to a low-spin acylperoxoiron(III) center. Unfortunately, contaminants accompanying the 2(PAA) samples prevented determination of the iron oxidation state by Mossbauer spectroscopy. Use of MeO-PyNMe3 (an electron-enriched version of PyNMe3) and cyclohexyl pero…
Translational dynamics effects on the non-local correlations between two atoms
2005
A pair of atoms interacting successively with the field of the same cavity and exchanging a single photon, leave the cavity in an entangled state of Einstein-Podolsky-Rosen (EPR) type (see, for example, [S.J.D. Phoenix, and S.M. Barnett, J. Mod. Opt. \textbf{40} (1993) 979]). By implementing the model with the translational degrees of freedom, we show in this letter that the entanglement with the translational atomic variables can lead, under appropriate conditions, towards the separability of the internal variables of the two atoms. This implies that the translational dynamics can lead, in some cases, to difficulties in observing the Bell's inequality violation for massive particles.
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…