Search results for "Ordination"
showing 10 items of 1367 documents
Semiconductive and Magnetic One-Dimensional Coordination Polymers of Cu(II) with Modified Nucleobases
2013
Four new copper(II) coordination complexes, obtained by reaction of CuX2 (X = acetate or chloride) with thymine-1-acetic acid and uracil-1-propionic acid as ligands, of formulas [Cu(TAcO)2(H2O)4]·4H2O (1), [Cu(TAcO)2(H2O)2]n (2), [Cu3(TAcO)4(H2O)2(OH)2]n·4H2O (3), and [Cu3(UPrO)2Cl2(OH)2(H2O)2]n (4) (TAcOH = thymine-1-acetic acid, UPrOH = uracil-1-propionic acid) are described. While 1 is a discrete complex, 2-4 are one-dimensional coordination polymers. Complexes 2-4 present dc conductivity values between 10(-6) and 10(-9) S/cm(-1). The magnetic behavior of complex 2 is typical for almost isolated Cu(II) metal centers. Moderate-weak antiferromagnetic interactions have been found in complex…
Effect of temperature and ligand protonation on the electronic ground state in Cu( ii ) polymers having unusual secondary interactions: a magnetic an…
2018
International audience; Two new copper(II) polymeric complexes, {[Cu(HPymat)(H2O)](NO3)}n (1) and [Cu2(Pymat)2(H2O)3]n (2), have been synthesized using the Schiff base ligand H2Pymat [H2Pymat = (E)-2-(1-(pyridin-2-yl)-methyleneamino)terephthalic acid]. Complex 1 is a cationic 1D polymer, whereas complex 2 is a two dimensional polymer. Both complexes were crystallographically, spectroscopically and magnetically characterized. Theoretical studies were performed and the catecholase activity of the complexes was also examined. Complex 1 is a ferromagnetically coupled complex with J = 2.8 cm−1 and 2 shows antiferromagnetic coupling with J = −1.6 cm−1. Both complexes show notable features in the …
Exploring the redox reactivity of magnesium porphine. Insight into the origins of electropolymerisation.
2010
International audience; Magnesium(II) porphine, MgP (1), was synthesised according to the Lindsey procedure allowing to isolate and crystallise 1-formyldipyrromethane (2) as a synthetic intermediate. Unprecedented Xray diffraction studies revealed multiple intermolecular associations in the crystal between neighbouring units of 2, namely hydrogen bond and CH … π. The electrochemical behaviour of 1 was examined by means of cyclic voltammetry. In oxydation, two well-defined and distinct steps are assigned to macrocycle concerned electron transfers yielding initially the π-cation radical and π dication, respectively. The highly reactive dication condenses neutral magnesium porphine to form a d…
A phenoxo-bridged dicopper(ii) complex as a model for phosphatase activity: mechanistic insights from a combined experimental and computational study
2017
A μ-phenoxo-bis(μ2-1,3-acetato)-bridged dicopper(II) complex [CuII2(L1)(μ-O2CMe)2][NO3] (1) has been synthesized from the perspective of modeling phosphodiesterase activity. Structural characterization was done initially with 1·3Et2O (vapour diffusion of Et2O into MeOH solution of 1; poor crystal quality) and finally with its perchlorate salt [CuII2(L1)(μ-O2CMe)2][ClO4]·1.375MeCN·0.25H2O, crystallized from vapour diffusion of n-pentane into a MeCN–MeOH mixture (comparatively better crystal quality). An asymmetric unit of such a crystal contains two independent molecules of compositions [CuII2(L1)(μ-O2CMe)2][ClO4] and [CuII2(L1)(μ-O2CMe)2(MeCN)][ClO4] (coordinated MeCN with 0.75 occupancy), …
Isolation, characterization, and computational studies of the novel [Mo3(mu3-Br)2(mu-Br)3Br6]2- cluster anion.
2010
The novel trimolybdenum cluster [Mo(3)(mu(3)-Br)(2)(mu-Br)(3)Br(6)](2-) (1, {Mo(3)}(9+), 9 d-electrons) has been isolated from the reaction of [Mo(CO)(6)] with 1,2-C(2)H(4)Br(2) in refluxing PhCl. The compound has been characterized in solution by electrospray ionization mass spectrometry (ESI-MS), UV-vis spectroscopy, cyclic voltammetry, and in the solid state by X-ray analysis (counter-cations: (n-Bu)(4)N(+) (1), Et(4)N(+), Et(3)BzN(+)), electron paramagnetic resonance (EPR), magnetic susceptibility measurements, and infrared spectroscopy. The least disordered (n-Bu)(4)N(+) salt crystallizes in the monoclinic space group C2/c, a = 20.077(2) A, b = 11.8638(11) A, c = 22.521(2) A, alpha = 9…
Coordination of Cu2+ Ions to C2 Symmetric Pseudopeptides Derived from Valine
2010
The acid-base and coordination properties of a family of pseudopeptidic ligands with C(2) symmetry derived from valine (4a-e) have been studied using a variety of techniques as a model for metal coordination in peptides and proteins. The Cu(2+) cation has been selected for coordination studies, although, for comparison, some results for Zn(2+) are also presented. Good agreement has been obtained between the results obtained by potentiometric titrations, spectroscopic analysis, and mass spectrometry (ESI) studies. These results highlight the potential for the use of ESI MS for characterizing the nature of the complex species formed. Clearly, the Cu(2+) complexes are much more stable than the…
Experimental and Computational Studies of Hydrogen Bonding and Proton Transfer to [Cp*Fe(dppe)H]
2005
The present contribution reports experimental and computational investigations of the interaction between [Cp*Fe(dppe)H] and different proton donors (HA). The focus is on the structure of the proton transfer intermediates and on the potential energy surface of the proton transfer leading to the dihydrogen complex [Cp*Fe(dppe)(H2)]+. With p-nitrophenol (PNP) a UV/Visible study provides evidence of the formation of the ion-pair stabilized by a hydrogen bond between the nonclassical cation [Cp*Fe(dppe)(H2)]+ and the homoconjugated anion ([AHA]-). With trifluoroacetic acid (TFA), the hydrogen-bonded ion pair containing the simple conjugate base (A-) in equilibrium with the free ions is observed…
Functional superoxide dismutase mimics. Structural characterization and magnetic exchange interactions of copper(II)-N-substituted sulfonamide dimer …
2004
Dinuclear copper(II) complexes with N-substituted sulfonamide ligands as superoxide dismutase (SOD) mimics have been investigated. The new N-(thiazol-2-yl)toluenesulfonamide (Htz-tol) and N-(thiazol-2-yl)naphthalenesulfonamide (Htz-naf) ligands have been prepared and structurally characterized. The complexes derived from these ligands, [Cu(2)(tz-tol)(4)] (1) and [Cu(2)(tz-naf)(4)] (2), have been synthesized, and their crystal structure, magnetic properties, and EPR spectra were studied in detail. In both compounds the metal centers are bridged by four nonlinear triatomic NCN groups. The coordination geometry of the coppers in the dinuclear entity of 1 and 2 is distorted square planar with t…
Bioinspired manganese(II) complexes with a clickable ligand for immobilisation on a solid support.
2014
International audience; Clickable ligands like N,N′-bis((pyridin-2-yl)methyl)prop-2-yn-1-amine (L1) and N-((1-methyl-1H-imidazol-2-yl)methyl)-N-(pyridin-2-ylmethyl)prop-2-yn-1-amine (L2) have been used to synthesise a series of manganese(II) complexes for grafting onto appropriate solid supports. These ligands mimic the 2-His-1-carboxylate facial chelation present in the active site of the manganese-dependent dioxygenase (MndD), while the alkyne side function allows grafting of the ligand onto an azido-functionalised support using “click chemistry” methodologies. Such synthetic analogues of the MndD crystallise in the solid state as double halide or pseudohalide-bridged dinuclear manganese(…
Pyrophosphate-mediated magnetic interactions in Cu(II) coordination complexes.
2010
The reaction in water of Cu(NO(3))(2)·2.5H(2)O with 2,2'-bipyridine (bipy), 1,10-phenanthroline (phen), or 1,10-phenanthroline-5-amine (phenam), and sodium pyrophosphate (Na(4)P(2)O(7)), at various pHs, afforded three new copper(II)-pyrophosphate complexes, namely, {[Cu(bipy)(cis-H(2)P(2)O(7))](2)}·3H(2)O (1a), {[Cu(phen)(H(2)O)](4)(HP(2)O(7))(2)}(ClO(4))(2)·4H(2)O (2), and {[Cu(2)(phenam)(2)(P(2)O(7))](2)·25H(2)O}(n) (3). A solvent free crystalline phase of 1a was also isolated with formula {[Cu(bipy)(trans-H(2)P(2)O(7))](2)} (1b), which can be regarded as a pseudo-polymorph of 1a. Single crystal X-ray analyses revealed these compounds to have uncommon molecular architectures, with 3 being…