Activite optique de polyamines tertiaires du type poly[thio-(N-R1-N-R2 aminomethyl)-1 ethylene]

Ultra-violet, ORD and CD spectra of (?)poly[thio1-(N-N-diethylaminomethyl) ethylene] (Ia) prepared by stereoelective polymerization of racemic N-N-diethyl-N-(thiirane-2-ylmethyl) amine using ZnEt₂-(—) 3-3-dimethyl-1,2 butanediol as initiator system, of (+)poly[thio1-(N-N-diethyl aminomethyl) ethylene] obtained from a partially resolved enantiomer using ZnEt₂-CH₃OH as initiator system, of poly[thio1-(N-methyl-N-sec-butyl aminomethyl) ethylene] and of poly[thio1-(N-methyl-N-(1-phenylethyl) aminomethyl) ethylene] in organic solvents (tertiary amine form) and in water (hydrochloride form) are described. Observed Cotton effects are associated with electronic transitions of chromophores by comparison with model molecules: N-methyl2-aminobutane, ethyl-thio-2-methylbutane and polypropylene sulfide. For polyamine (Ia), their contributions to optical rotatory powers in the visible are evaluated after decomposition of corresponding CD curves in Gaussian partial Cotton effects. The effects of other optically active electronic transitions located below 180 nm are deduced by difference. Influence of positions of chromophores with regard to chiral centers and of the protonation of nitrogen atoms on observed Cotton effects are discussed.     

Synthesis and spectroscopic studies of metal(II) complexes prepared withN-2-(5-picolyl)-N′-phenylthiourea

Summary The chlorides and bromides of cobalt(II), nickel(II) and copper(II) along with the acetates of the latter two metal ions and copper(II) tetrafluoroborate were used to prepare complexes ofN-2-(5-picolyl)-N-phenylthiourea (5MTUH). 5MTUH coordinates as a bidentate ligand via the pyridyl nitrogen and the sulphur atoms in the cobalt(II) complexes and the compounds isolated with Cu(BF₄)₂ and CuCl₂. Complexes of stoichiometry [Cu(5MTU)X] (X=Br or C₂H₃O₂) appear to have the deprotonated ligand coordinated via the pyridyl andN thioamide nitrogens and the sulphur atom. The nickel(II) complexes involve monodentate 5MTUH with sulphur being the donor atom. A violet, octahedral [Co(5MTUH)₂Cl₂] complex and a blue, tetrahedral [Co(5MTUH)Cl₂] complex have been isolated, but with CoBr₂ only an octahedral complex could be prepared.     

Electrochemical Properties of Crown-Containing N-(Thio)phosphoryl(thio)ureas and Their Complexes with 3d Transition Metals

The electrochemical behavior of crown-containing N-(thio)phosphoryl(thio)ureas and their complexes with 3d transition metals was studied by dc voltammetry on a graphite electrode in acetone. Crown-containing N-(thio)phosphoryl(thio)ureas are not reduced but are oxidized on solid electrodes in the examined range of potentials; the electrons are transferred via the (thio)urea group. Electrooxidation of macrocyclic Co(II), Ni(II), and Cu(II) complexes probably occurs via formation of M(III) complex species. Electroreduction of these metal complexes involves stepwise electron transfer, with the oxidation state of the metal atom decreasing to 0, followed by dissociation of the electrochemical reaction products.     

Four copper(II) complexes with potentially tetradentate tripodal ligands

The four title Cu^II compounds are chloro­[(2‐furyl­methyl)­bis(2‐pyridyl­methyl)­amine‐N,N′,N′′]copper(II) perchlorate, [CuCl(C₁₇H₁₇N₃O)]ClO₄, (I), chloro{2‐[bis(2‐pyridyl­methyl)­amino]­ethano­lato‐N,N′,N′′,O}­copper(II) hemi­[tetra­chloro­copper(II)], [CuCl(C₁₄H₁₇N₃O)][CuCl₄]_1/2, (II), chloro­[(2‐morpholino­ethyl)­bis(2‐pyridyl­methyl)­amine‐N,N′,N′′,N′′′]copper(II) perchlorate, [CuCl(C₁₈H₂₄N₄O)]ClO₄, (III), and chloro­[(2‐piperidinyl­ethyl)­bis(2‐pyridyl­methyl)­amine‐N,N′,N′′,N′′′]­copper(II) hexa­fluoro­phosphate, [CuCl(C₁₉H₂₆N₄)]­PF₆, (IV). They have tripodal potentially tetradentate ligands. In (I), the O atom of the furan moiety weakly coordinates to the Cu atom at a distance of 2.750 (3) Å.     

N-tripodal ligands to generate copper catalysts for the syndiotactic polymerization of methyl-methacrylate: Crystal structures of copper complexes

A library of N-tripodal ligands, based on a central nitrogen atom connected to three different functionalized arms, was investigated via a parallel approach for the polymerization of methyl-methacrylate (MMA) in presence of late transition metal salts. Copper salts CuCl₂ and Cu(OAc)₂ in combination with N-(2-furanylmethyl)-N-(1-3,5-dimethyl-1H-pyrazolylmethyl)-N- (phenylmethyl)amine were detected as efficient catalysts for the syndiotactic polymerization of MMA ([rr] up to 78%). Kinetic studies and X-ray structures of the best catalysts were reported.     

Structural diversity in pseudohalide complexes of cadmium(II) with N-methylthiourea (Metu): Polymeric [Cd(Metu)2(NCS)2]n versus monomeric [Cd(Metu)2(CN)2]

Cadmium(II) complexes, catena-poly[bis(thiocyanato-κN)bis(N-methylthiourea)cadmium(II)], [Cd(Metu)₂(NCS)₂]_n (1) and dicyanidobis(N-methylthiourea)cadmium(II), [Cd(Metu)₂(CN)₂] (2) were prepared and their structures were determined by single crystal X-ray analysis. In 1, the cadmium(II) ion is bound to four sulfur atoms of bridging Metu ligands and two nitrogen atoms of thiocyanate adopting a distorted octahedral environment. In 2, the geometry around cadmium is distorted tetrahedral attained by two cyanide ions and two methylthiourea molecules bound through the sulfur atoms. The crystal structures of both complexes show intra and intermolecular hydrogen bonding interactions. The complexes were also characterized by IR and NMR spectroscopy and the spectroscopic data were discussed in terms of the nature of bonding.     

Copper(II) chloride and bromide complexes with 2‐methyl‐2H‐tetrazol‐5‐amine: an X‐ray powder diffraction study

The complex catena‐poly[[dibromidocopper(II)]‐bis(μ‐2‐methyl‐2H‐tetrazol‐5‐amine)‐κ²N⁴:N⁵;κ²N⁵:N⁴], [CuBr₂(C₂H₅N₅)₂]_n, (I), and the isotypic chloride complex catena‐poly[[dichloridocopper(II)]‐bis(μ‐2‐methyl‐2H‐tetrazol‐5‐amine)‐κ²N⁴:N⁵;κ²N⁵:N⁴], [CuCl₂(C₂H₅N₅)₂]_n, (II), were investigated by X‐ray powder diffraction at room temperature. The crystal structure of (I) was solved by direct methods, while the Rietveld refinement of (II) started from the atomic coordinates of (I). In both structures, the Cu atoms lie on inversion centres, adopting a distorted octahedral coordination of two halogen atoms, two tetrazole N atoms and two 5‐amine group N atoms. Rather long Cu—N_amine bonds allow consideration of the amine group as semi‐coordinated. The compounds are one‐dimensional coordination polymers, formed as a result of 2‐methyl‐2H‐tetrazol‐5‐amine ligands bridging via a tetrazole N atom and the amine N atom. In the polymeric chains, adjacent Cu atoms are connected by two such bridges.     

A thiophenopolyamine Cu(II) complex fixed by atmospheric carbon dioxide: synthesis,structure and properties

A new trinuclear complex, {[Cu(L)]₃ (μ₃-CO₃)}(ClO₄)₄ (L = N-(2-thiophenoethyl)-N,N-bis (3-aminopropyl)amine), was synthesized and characterized by single-crystal X-ray analysis. The complex contained three identical mononuclear copper(II) units connected by the μ₃-carbonate formed from atmospheric carbon dioxide. The electronic and magnetic properties were studied by cyclic voltammetry and the measurement of magnetic susceptibility, respectively. The μ₃-bridging model revealed weak ferromagnetic coupling of Cu(II), with the J value of ?11.28 cm^?1 and the Zeeman splitting g value of 2.06, which were determined by means of magnetic measurements in the 2–300 K range.     

Complexing of Cu(II) with N,N'-Diphenylthiooxamide and N,N'-Diphenyldithiooxamide in a Gelatin-Immobilized Cu2[Fe(CN)6] Matrix

A study was made of complexing in Cu(II)-N'N'-diphenylthiooxamide, Cu(II)-N'N'-di-phenyldithiooxamide systems in gelatin-immobilized Cu₂[Fe(CN)₆] matrices brought into contact withaqueous alkaline (pH 12.0±0.1) solutions of these ligands. In both cases, complexing is preceded by alkaline breakdown of copper(II) hexacyanoferrate(II) into Cu(II) hydroxide or oxohydroxide which is the species reacting with the ligands. In each system, complexing yields a Cu(HL)2 chelate (HL^- is the single-deprotonated form of N,N'-diphenylthiooxamide or N,N'-diphenyldithiooxamide).     

Copper(II) and cadmium(II) complexes of 2-benzylthio-4-formyl-1-p-methoxyphenylimidazole: crystal structure,spectral properties and thermal behaviour

Summary The coordinative capacity of 2-benzylthio-4-formyl-1-p-methoxyphenylimidazole (ALME) with several transition metal ions has been investigated and has led to only copper(II) and cadmium(II) complexes of general formula [M^IICl₂(ALME)₂]·nH₂O. These compounds were studied by spectral (i.r., u.v.-vis. n.i.r. and e.p.r.) and thermal methods (t.g., d.t.g. and d.s.c.) as well as magnetic susceptibility measurements.The crystal structure of the copper complex has been solved, although a full refinement of the structure has not been possible as very few measured reflections were observed. The structure consists of discrete [CuCl₂-(ALME)₂] units in which Cu(II) ion is 4 + 2 Cl₂N₂O₂ surrounded [Cu{ie481-01}Cl(1), 2.28(1) Å; Cu{ie481-02}Cl(2), 2.29(1) Å; Cu{ie481-03}N, 2.00(2) Å; Cu{ie481-04}O, 2.71(2) Å]. The ALME ligand acts as bidentate chelator through the N(3) imidazolic atom and the oxygen of the formyl group, the Cu{ie481-05}O interaction being very weak. Water molecules have not been localized.     

Synthesis of (-)-(S)-3-sec-butyl- and (+)-(S)-5-sec-butyl-2(1H)-pyridinone

Optically active (+)-(S)-5-sec-butyl- and (-)-(S)-3-sec-butyl-2(1H)-pyridinone are synthesized and the relationship between optical activity and minimum optical purity of the latter is determined.     

Kinetics and mechanism of the amine exchange reactions of 2-aminopyridine derived Schiff-base ligands and their copper(II) complexes

The kinetics and product analyses of the amine exchange reactions of two 2-aminopyridine derived Schiff-base ligands and their monomeric bischelate and dimeric copper(II) complexes have been studied. The Schiff-base ligands investigated underwent amine exchange reactions with n-butyl, cyclohexyl, t-butyl amines. The coordination of the Schiff-base ligands to copper(II) rendered the amine exchange reactions slower. With n-butyl and cyclohexyl amines, parallel first- and second-order terms on their concentrations are observed for the amine exchange reactions of copper(II) bischelates and dimer. The kinetic data favor a mechanism involving a rate-limiting elimination of 2-aminopyridine from a diaminoacetal intermediate in preference to a scheme in which a dissociation of the complexes into free ligands and Cu(II) may precede the amine exchange. The steric factors influence the amine exchange reactions of Cu(II) bischelates with the bulkier amines reacting slower as given by the order t-butylamine (3.3 ± 0.3 × 10^?3 dm³/mol·s) < cyclohexylamine (0.2 ± 0.03 dm³/mol·s) < n-butylamine (2.2 ± 0.2 dm³/mol·s). The bulkiness of the t-butyl group and the constraints imposed by the changes in the coordination geometry of Cu(II) on amine exchange not only render the reactions of Cu(II) bischelates slower but also make the formation of the mixed adduct ([N-(5-methyl)-2-pyridyl salicylaldimine][N-t-butyl salicylaldimine] Cu(II)) more favored.     

Kinetics of metal exchange reaction of Cu(II)-poly(vinyl alcohol) complex with Ca(II)-ethylenediamine-N,N,N′,N′-tetraacetic acid in aqueous solution

The kinetics of the metal exchange reaction between the Cu(II)-poly(vinyl alcohol) complex (Cu(II)-PVA) and Ca(II)-ethylenediamine-N,N,N′,N′-tetraacetic acid (Ca(II)-EDTA) were studied by mixing both solutions in a spectrophotometer at pH 9.7–11.0, at μ = 0.10(KNO₃) and at 25°C. The reaction is initiated by the formation of unstable Cu(II)-H-PVA by the attack of H⁺ to Cu(II)-PVA, and while both ligand exchange and metal exchange steps occur, the latter may be rate-determining. The kinetic expression of this reaction was determined as -d[Cu(II)-PVA]/dt = k[Cu(II)-PVA] [H⁺] [PVA]/[Ca(II)-EDTA], where k = k₁ + k′₂[H⁺], k₁ = 3.85 × 10⁻² sec⁻¹, k₂ = k′₂ · K^−H_Cu(II)-H-PVA 9.59 × 10⁵ 1 mol⁻¹ sec⁻¹.     

Reactions of Bis(β-Alaninato) Metal(II) Complexes with Formaldehyde and Benzamide: The Crystal Structure of Bis[N-Methyl-N-(N′-Methyl-Benzamido)-β-Alaninato]Copper(II) Monohydrate and Characterization of Bis[N,N-DI(N′-Methylbenzamido)-β-Alaninato]Metal(II) Complexes

The bis[N-methyl-N-(N'-methylbenzamido)-β-alaninato]copper(II), Cu(II)[Me-MeBA]₂, is synthesized by reacting bis(β-alaninato)copper(II) with formaldehyde and benzamide in the presence of a base (NaOH) over the pH range 5.5-8.5. However, the bis[N,N-di (N'-methylbenzamido)-β-alaninato]metal(II) complexes, M(II)[DMeBA]₂ (M = Zn, Ni, Co), are obtained when the respective bis(β-alaninato)metal(II) reacts with formaldehyde and benzamide in the presence of the base in similar pH ranges. Nevertheless, Cu(II)[DMeBA]₂ can be synthesized if the reaction is carried out in the absence of base. The M(II)[DMeBA]₂ complexes are characterized by elemental analysis, IR and UV-Visible spectroscopy and magnetic susceptibility measurements. X-ray crystal structure analysis of Cu(II)[Me-MeBA]₂ suggests that the N'-methylbenzamido substituent of the β-alanine moiety is formed through Mannich aminomethylation, and that the other N-methyl substituent is formed via a Canizzaro-type methylation.     

Radiolytic reductions of Ag(I), Cu(II), Hg(II) and Pb(II) in aqueous-ethanol systems and the effect of colloidal sulfur

Radiation-induced reductions in aqueous AgClO₄, CuCl₂, PbCl₂ and HgCl₂ systems have been measured in the presence of ethanol and for Ag(I) and Cu(II) with several other organic components. In dilute solutions and under deaerated conditions, the rates were consistent with known radical yields and rate constants. Approximately one-third of the radicals formed from ethanol under conditions of complete OH scavenging are ineffective in reducing Cu(II). In the presence of colloidal Cu or Ag, all of the radicals are effective in the reduction. In the presence of 0.4–2 × 10^-3 g-atom 1^-1 of colloidal sulfur, sulfur reduction competes with and augments that of Ag(I) and Cu(II). Ag₂S and CuS are formed with a reaction chain occuring in the Ag system at 1.7 M ethanol. A mechanism is suggested that involves reaction of a radical-cation complex at the sulfur-aqueous interface in which the metal sulfide is formed. HgCl₂ reduction is unaffected by colloidal sulfur and that of PbCl₂ is depressed.     

Preparation and characterization of copper sulfide nanoparticles from symmetrical [(Bu)2NC(S)NC(O)C6H3(3,5-NO2)2]2Cu(II) and [(Bu)2NC(S)NC(O)C6H4(4-NO2)]2Cu(II) complexes by thermolysis

Trigonal copper sulfide nanoparticles were synthesized from symmetrical [(Bu)₂NC(S)NC(O)C₆H₃(3,5-NO₂)₂]₂Cu(II) and [(Bu)₂NC(S)NC(O)C₆H₄(4-NO₂)]₂Cu(II) complexes by thermolysis in the presence of surfactant oleylamine. The symmetrical copper complexes were synthesized by reaction of copper(II) acetate with N-(3,5-dinitrobenzoyl)-N′,N′-dibutylthiourea and N-(4-nitrobenzoyl)-N′,N′-dibutylthiourea. The symmetrical copper complexes were characterized by FT-IR spectroscopy, elemental analysis, and mass spectrometry (MS-APCI). The single-crystal X-ray structure of [(Bu)₂NC(S)NC(O)C₆H₄(4-NO₂)]₂Cu(II) has been determined from single-crystal X-ray diffraction data. These metal complexes have been used as single source precursors for the preparation of copper sulfide nanoparticles. The deposited copper sulfide nanoparticles were characterized by X-ray powder diffraction and transmission electron microscopy.     

The synthesis and characterization of a new (E,E)-dioxime containing 18-membered dithiadiazadioxamacrocyclic moieties and its mononuclear complexes

A new (E,E)-dioxime, (21Z,22Z)-6,7,9,10,12,13-hexahydro-16H- benzo[h][1,4,7,16,10,13][1, 4,7,16,10,13]dioxadithiadiazacyclooctadecine-21,22(20H,23H)-dione dioxime (H ₂ L) has been synthesized by reacting cyanogen-di-N-oxide (2) with (2-{[2-(2-{2-[(7-aminocyclohepta-1,4,6-trien-1-yl)thio]ethoxy}ethoxy)ethyl]thio}phenyl)amine. Mononuclear complexes of this ligand have been synthesized by reacting the vic-dioxime (H₂L) with CuCl₂, NiCl₂.6H₂O and CoCl₂.6H₂O respectively. The BF₂⁺ capped Ni(II) and Co(III) complexes of the dioxime have been synthesized from. The new compounds were characterized by a combination of elemental analysis, ¹H- and ¹³C-n.m.r, I.R. and m.s. spectral data.     

Schiff-Basen aus 1,3-Dicarbonylverbindungen und Triaminen und ihre Fe (III)-, Co (III)-, Ni(II)- und Cu(II)-Komplexe

Schiff bases of 1,3-dicarbonyl compounds with triamines and their Fe(III), Co(III), Ni(II) and Cu(II) complexes The preparation of new hexadentate ligands obtained by the reaction of cis, cis-1,3,5-triaminocyclohexane (tach) or 1,1,1-tris (aminomethyl)ethane (tame) with an 2-ethoxymethylidene-1,3-dicarbonyl compound as well as their Fe(III), Co(III), Ni(II) and Cu(II) complexes is reported. Fe(III) and Co(III) yield neutral complexes with an octahedral N₃O₃-coordination sphere, Ni(II) and Cu(II) complexes with a square-planar coordination-sphere. In the later complexes one of the bidentate branches of the ligand is not deprotonated and stays uncoordinated.     

Copper (II)-thiolate complexes with novel tripodal- and tetrapodal-like benzimidazoles

Summary The tripodal copper(II) thiolate complexes Cu(L1)(Cl)-2H₂O and Cu(L1)(mim)(Cl) [H(L1) = N-(2-mercaptoethyl)-N,N-bis (pyrid-2-ylmethyl)amine and mim = N-methylimidazole] have been isolated. Both contain monomeric copper(II) and display two ligand field bands and axial cryogenic e.p.r. spectra, suggesting a squarebased geometry. A copper(II) thiolate complex Cu(L2)(Cl)-H₂O [H(L2) = N-(2-mercaptoethyl)-N,N,N-tris(benzimidazol-2-ylmethyl)-1,2-ethanediamine] with a CuN₅S chromophore has been also isolated. It exhibits only one ligand field band and an axial cryogenic e.p.r. spectrum, consistent with a distorted tetragonal coordination geometry. All the thiolates display intense S^– Cu^II charge transfer bands in the u.v. region, suggesting equatorial thiolate coordination. All of the complexes exhibit irreversible electrochemical behaviour.     

Di­chloro­bis­(glycocy­amine-O)copper(II)

The title compound, [CuCl₂(C₃H₇N₃O₂)₂], is a new copper(II) complex with glycocy­amine [(di­amino­methyl­ene­amino)­acetic acid], the first complex ever reported with this organic mol­ecule. It is composed of discrete centrosymmetric coordinated Cu^II monomers, the Cu atoms being located at inversion centers. Each metal ion is square-planar coordinated by two Cl atoms and two glycocy­amine O atoms. The coordinating glycocy­amine mol­ecule exists as a zwitterion, the H atom from the carboxyl group being transferred to the guanidinium group. A three-dimensional network of hydrogen bonds links the monomers and stabilizes the structure.