Eric Deydier

Adsorption of Cu(II) and Pb(II) onto a grafted silica: isotherms and kinetic models

The isotherms and kinetics of adsorption of lead(II) and copper(II) onto a grafted silica are studied at 20 degrees C. A commercial silica is grafted with an ethylediamine derivative, N-[3-(trimethoxysilyl)propyl]-ethylenediamine. From the Langmuir isotherms, maximum adsorption capacities of the grafted silica towards Pb(II) and Cu(II) are determined (0.184 mmol Pb(II)g-1 and 0.261 mmol Cu(II)g-1) and compared to those of non-modified silica (respectively, 0.019 and 0.036 mmol g-1). Four kinetic models, i.e., pseudo-first order, pseudo-second order, Langmuir and double-exponential are applied to fit the experimental kinetic data. The kinetic parameters are determined which allow to calculate the theoretical metal uptake as a function of time. The results are discussed and indicate the best fit is obtained with the double-exponential model. A discussion on the adsorption mechanism with respect to the double-exponential model leads to two possible interpretations: the metal uptake may follow a diffusion-controlled mechanism or a two-site adsorption process.

Beneficial use of meat and bone meal combustion residue: “an efficient low cost material to remove lead from aqueous effluent”

Meat and bone meal (MBM) combustion residues, a natural apatite-rich substance, was evaluated as a low cost substitute for hydroxyapatite in lead sequestration from water effluents. The thermal behaviour of crude meat and bone meal was followed by TGA and 24% inorganic residue was collected. The resulting ashes were characterised by powder X-ray diffraction (XRD), particle size distribution, specific surface area (BET), and elemental analysis confirming apatite contents, with high level of phosphate (56.3%) and calcium (36.8%). Mechanism and kinetics of lead removal by this bioinorganic material were investigated and compared to mechanisms and kinetics involved with synthetic apatite. Batch metal removal experiments were carried out with 500 and 1500ppm (mg/kg) Pb(2+) solutions. Lead concentration, calcium and pH were monitored. We observed that the mechanism is similar to that occurring for pure apatite, and involved both surface complexation and calcium hydroyapatite (CaHA), Ca(10)(PO(4))(6)(OH)(2), dissolution followed by less soluble Pb(10)(PO(4))(6)(OH)(2) precipitation, as confirmed by XRD analysis of ashes after incubation with lead solution. Our results show that this natural apatite-rich material removes in a few minutes a large quantity of lead (275mg/g capacity) which remains however lower than the theoretical maximum capacity (if calcium were totally substituted by lead). Meat and bone meal combustion residues represent a valuable alternative apatite source for environmental application.

Crystal and molecular structures of transition metal complexes with N- and C-bonded diazoalkane ligands

Abstract The review covers structural and physicochemical studies on diazoalkanes N-coordinated to transition metals and encompasses all collected crystal structures. Our goal is to provide a classification of the complexes based on the metal, ranging from early to late transition metals, the nuclearity of the complex (mono, dinuclear, clusters), the electronic configuration of the metal (d 0 to d 10 ) and the bonding mode of the diazoalkanes. Interestingly, the variety of structures may be rationalized within the valence bond formalism, the reactions being essentially oxidative addition of diazoalkane on the metal complexes giving hydrazonido (-2- ligand). C-coordinated diazoalkyl complexes are still restricted to a few metals and a few diazosubstituents and their chemistry is not well developed.

Synthesis and characterization of new copper(II) and nickel(II) complexes of 3-(2'-hydroxyphenyl)-1,2,4-triazine derivatives

The copper(II) and nickel(II) complexes of 5,6-diphenyl-3-(2?-hydroxyphenyl)-1,2,4-triazine, noted HLH, and 5,6-bis (4methoxyphenyl)-3-(2?-hydroxyphenyl)-1,2,4-triazine, noted HLOMe ,h ave been synthesized from copper(II) acetate in CH2Cl2 and nickel(II) nitrate in acetone with an excess of previously deprotonated triazine. The new complexes [Cu(LH)2]/H2 O( 1), [Cu(LOMe)2]/ 2H2 O( 2), Na[Ni(LH)3]/2H2O/(CH3)2CO (3), and Na[Ni(LOMe)3]/2H2 O( 4) were isolated as pure solids and characterized by IR, UV � /Vis, elemental analysis and mass spectra. Copper(II) complexes 1 and 2 were studied by EPR, in frozen solutions. In accordance with the spectroscopic data obtained by UV � /Vis, the stoichiometry of the complexes was found to be 1:2 for Cu 2� :LH,OMe with a square planar environment for the metal centre. Crystals of HLOMe and 3 were obtained and studied by single crystal X-ray diffraction. The structure of HLOMe exhibits a strong deviation from planarity of the two p -methoxyphenyl rings with respect to the triazine ring while the 2-hydroxyphenyl fragment is almost coplanar. Intramolecular hydrogen bonding between one of the N atoms of the triazine ring and the phenol can explain this restraint. For 3, three LH bidentate triazines are coordinated to the nickel ion in a distorted octahedral manner. # 2003 Elsevier B.V. All rights reserved.

Evaluation of laboratory and industrial meat and bone meal combustion residue as cadmium immobilizing material for remediation of polluted aqueous solutions: Chemical and ecotoxicological studies

Meat and Bone Meals (MBM) combustion residues (ashes) are calcium and phosphate-rich materials. The aim of this work is to evaluate ashes efficiency for remediation of cadmium-contaminated aqueous solutions, and to assess the bioavailability of cadmium on Xenopus laevis larvae. In this study both industrial (MBM-BA) and laboratory (MBM-LA) ashes are compared regarding their efficiency. Kinetic investigations reveal that cadmium ions are quickly immobilized, with a maximum cadmium uptake at 57 mg Cd(2+)/g of ashes for MBM-LA, two times higher than metal uptake quantity of MBM-BA, in our experimental conditions. Chemical and X-ray diffraction analysis (XRD) reveal that Cd(2+) is mainly immobilized as Ca(10-x)Cd(x)(PO(4))(6)(OH)(2) by both ashes, whereas otavite, Cd(CO(3)), is also involved for MBM-LA in cadmium uptake. Otavite formation could be explained by the presence of carbonates in MBM-LA, as observed by IR. Genotoxicity of cadmium solution on Xenopus larvae is observed at 0.02, 0.2 and 2mg Cd(2+)/L. However addition of only 0.1g/L MBM-LA inhibits these effects for the above concentration values whereas Cd(2+) bioaccumulation in larvaes liver is similar for both experiments, with and without ashes.

Interaction of Zn2+ with N-(2-pyridyl)-3-phenyl-2-propene amide, a model in lignin biosynthesis inhibition by cinnamides. Crystal and molecular structure of [Zn(ON)2(CH3OH)2](CF3SO3)2

Abstract Reacting Zn(CF3SO3)2 with the title ligand (ON) yields a 1:2 complex which precipitates from methanol as the [Zn(ON)2(CH3OH)2](CF3SO3)2 salt. The crystal structure of this complex (P11/c, a=13.711(2), b=10.401(2), c=16.358(2) A, β=124.27(1)°, R=0.059, 1918 observed reflections) reveals the presence of a centrosymmetric, nearly octahedral, complex cation. The all-trans configuration about Zn2+ is achieved by two methanol hydroxyl groups and two bidentate ligands bonded via their pyridyl nitrogens and amide oxygens. The amide group nitrogen is not coordinated to the metal, but it forms an NH.…O hydrogen bond to the CF3SO3− counterions. The influence of the amide substituent on the structure is discussed on the basis of comparisons with the [Zn{N-(2-pyridyl)acetamide}2(H2O)2]2+ ion containing a similar amidopyridine chelate ring.

N-(2-pyridyl)-3-phenyl-2-propene amide (O-N) complexes fo copper(II), nickel(II), cobalt(II) and palladium(II). Crystal and molecular structure of Cu(O-N)2(CF3SO3)2

Abstract The reaction of the title ligand N-(2-pyridyl)-3-phenyl-2-propene amide (O-N) with MX2 salts yields compounds of the type M(O-N)2X2 and [M(O-N)2(H2O)2]X2, which were characterized by elemental analysis, magnetic moments and IR and EPR spectroscopies. From the IR spectra the ligand is found to be bidentate via the pyridyl nitrogen and the amide oxygen, except in [Pd(O-N)2Cl2] where only the pyridyl ring is coordinated. The magnetic moments, IR spectra and thermograms of the M(O-N)2(NO3)2·3H2O compounds [M = nickel(II), cobalt(II)] are consistent with the presence of trans-[M(O-N)2(H2O)2]2+ ions, similar to the trans-[Zn(O-N)2(CH3OH)2]2+ species observed earlier. The EPR spectra of the trans-Cu(O-N)2X2 compounds (X = NO3−, CF3SO3−) indicate an elongated octahedral coordination with equatorial bidentate (O-N) ligands and solvent molecules or anions in axial sites. The solid-state spectra reveal the presence of more than one type of copper(II) centre. The crystal structure of trans-Cu(O-N)2(CF3SO3)2 was determined by X-ray diffraction. The unit cell contains two types of discrete trans-Cu(O-N)2(CF3SO3)2 molecules, in which bidentate (O-N) ligands are strongly bonded to the equatorial sites of a tetragonally distorted octahedron. The axial positions are filled by

Reaction of [(PEt3)3Rh{C(N2)SiMe3}] with terminal alkynes—synthesis of σ-alkynyl rhodium(III) complexes

Abstract Reaction of [(PEt3)3Rh{C(N2)SiMe3}] with two equivalents of HCCR (R  SiMe3, Ph, or tBu) affords the RhIII complex [(PEt3)3RhH(CCR)2] in high yield, showing that the trimethylsilyldiazomethyl group behaves like an alkyl group. The reaction was followed by 31P and 1H NMR spectroscopy. The first step is the oxidative addition of alkyne to the metal, which is followed by elimination of trimethylsilyldiazomethane and formation of [(PEt3)3Rh(CCR)].

Reaction of tris(triethylphosphine)trimethylsilyldiazomethylrhodium(I) with isocyanides. Synthesis and X-ray structure of the first 1H-1,2,3-triazolato complex with a metal–carbon bond

Two new C-bonded 1H-1,2,3-triazolato rhodium(I) compounds have been synthesized from the 1,3-dipolar cycloaddition of the diazo complex [Rh(PEt3)3{C(N2)SiMe3}] with isocyanides RNC (R = But and Bun).

The cocrystal rac-1-[(N,4-dimethylbenzenesulfonamido)methyl]-2-(diphenylphosphoryl)ferrocene-rac-1-[(N,4-dimethylbenzenesulfonamido)methyl]-2-(diphenylphosphanyl)ferrocene (0.45/0.55).

As part of our interest in the synthesis and catalytic applications of chiral (diphenylphosphanyl)ferrocene ligands, we designed a number of P,N-containing ligands for use in asymmetric transfer hydrogenation (ATH). During the synthetic procedure to obtain rac-1-[(N,4-dimethylbenzenesulfonamido)methyl]-2-(diphenylphosphanyl)ferrocene, the title compound, [Fe(C5H5)(C26H25NO2PS)]0.55 · [Fe(C5H5)(C26H25NO3PS)]0.45, was obtained as a by-product. It is composed of a ferrocene group disubstituted by a partially oxidized diphenylphosphanyl group, as confirmed by (31)P NMR analysis, and an (N,4-dimethylbenzenesulfonamido)methyl substituent. Owing to the partially oxidized diphenylphosphanyl group, it is best to view the crystal as being composed of a mixture of non-oxidized and oxidized phosphane, so it can be regarded as a cocrystal. It is also a racemate. To the best of our knowledge, the P=O distance [1.344 (4) Å] is the shortest observed for related (diphenylphosphoryl)ferrocene compounds. The packing is stabilized by weak C-H...O interactions, forming R2(2)(10) hydrogen-bonding motifs, which build up a chain along the c axis.