Jean-Pierre Barbier

Bis-aminals: efficient tools for bis-macrocycle synthesis

Tetraazamacrocyclic bis-aminals prove to be excellent tools for the synthesis of symmetrical, dissymmetrical or functionalized bis-tetraazamacrocycles. The key feature of the process is the separation of insoluble mono- or bis-quaternary ammonium salts from solution during the course of the alkylation reaction.

Copper, nickel and cobalt complexes with N,N-disubstituted′-benzoyl thioureas

Abstract The complexes of 8 N,N-disubstituted,N′-benzoyl thioureas with copper, nickel and cobalt have been studied. NMR spectra and magnetic measurements have shown square planar NiL 2 and fac CoL 3 compounds. The electrochemical parameters obtained from cyclic voltammetry for the irreversible process copper(II)/copper(I) redox systems are slightly influenced by the different substituents.

Synthesis and characterization of copper, nickel and cobalt complexes with N-disubstituted, N′-ethoxy carbonyl thioureas

Abstract The complexes of N-disubstituted, N′-ethoxy carbonyl thioureas with copper, nickel and cobalt have been synthesized and studied. NMR spectra and magnetic data have shown square-planar NiL 2 and fac- or mer -CoL 3 compounds. The existence of copper(III)/copper(II) and copper(II)/copper(I) redox systems has been chemically and electrochemically proved in solution.

Synthesis of N-morpholine or N,N-diethyl, N′-monosubstituted benzoyl thiourea copper complexes: characterization and electrochemical investigations

Abstract A series of N-morpholine or N,N-diethyl, N′-substituted benzoyl thioureas (R = Cl, Br, OMe or NO 2 in ortho, meta or para position) have been synthesized by condensation of morpholine or diethylamine with substituted benzoyl isothiocyanates. All CuL 2 complexes have been characterized. Cyclic voltammetry has shown that the irreversible process copper(II)/copper(I) redox systems are influenced slightly by the substitution, whereas the quasi-reversible copper(III)/copper(II) redox systems are not.

Copper(II) and nickel(II) complexes of pyridylamido hexadentate ligands: chemical speciation and spectroscopic studies

Abstract Two novel potentially hexadentate ligands, 1,10-(2-bis picolinamide)-4,7-diazadecane (pycdpnen) and 1,8-bis(2-picolinamide)-3,6-dioxaoctane (pycdado) have been synthesised as their hydrochloride salt; its protonation constants and the stability constants of the copper(II) and nickel(II) chelates have been determined by potentiometry. Amide groups deprotonation permits the formation of [MLH −1 ] + species in all cases, while only pycdado gives [MLH −2 ] species. The solid complexes of copper and nickel with the neutral and the deprotonated ligands have been synthesised and characterised by IR, UV–Vis and ESR spectroscopy. The amidic groups are coordinated through the oxygen atoms in all solid complexes [ML](ClO 4 ) 2 (M=Cu 2+ and Ni 2+ ). The complexes obtained with the deprotonated forms of the ligands imply the coordination through the nitrogen atoms of the amidic groups.

Synthesis and spectroscopic characterization of copper, nickel and cobalt complexes with N-(N″,N″-disubstituted-aminothiocarbonyl)-N′-substituted benzamidines

Abstract A series of copper(II), nickel(II) and cobalt(III) complexes with N -( N ″, N ″-disubstituted-aminothiocarbonyl)-N′-substitutedbenzamides have been synthesized and characterized. 1 H and 13 C NMR spectra have shown a mer configuration for the CoL 3 compounds. The NiL 2 complexes have a square-planar structure. Electron spin resonance spectra have shown that the presence of a bulky substituent on the nitrogen donor atom generates a large tetrahedral distortion around the copper in CuL 2 compounds. Cyclic voltammetry has revealed irreversible redox waves corresponding to the Cu(III)Cu(II) and Cu(II)Cu(II) couples.

Molecular structure and spectroscopic characterization of cobalt and copper complexes with a hexadentate nitrogen ligand, 1,10-bis(2-pyridylmethyl)-1,4,7,10-tetraazadecane

Abstract The syntheses of the cobalt(III) and copper(II) complexes with the hexadentate nitrogen ligand 1,10-bis(2-pyridylmethyl)-1,4,7,10-tetraazadecane (bpteta) are reported. NMR spectra and X-ray structure determination have shown that these octahedral complexes have a β-cis configuration with pyridine nitrogen atoms mutually cis and trans to amine nitrogen atoms. A large distortion due to the Jahn–Teller effect is observed in the case of the copper(II) compound.

Structural characterization by esr of copper complexes with unsymmetrical s,o or S,N bidentate thiourea derivative ligands

Abstract ESR spectra show the simultaneous presence of a planar trans and a nearly planar cis isomers in the 1:2 ratio for all S,O compounds Cu (R 1 R 2 N-CS-N-COR) 2 whereas an only isomer is present with the analogous S,N compounds. A strong tetrahedral distortion is observed when a bulky substituent is present on the nitrogen donor atom.

Synthesis and characterization of copper and nickel complexes with N-arylpyrrole-2-aldimines

Abstract A series of 17N-arylpyrrole-2-aldimine ligands has been synthesized by condensation of pyrrole-2-carboxaldehyde and substituted anilines. All CuL2 complexes are square, whereas NiL2 compounds are square, tetrahedral or eventually present a square α tetrahedral equilibrium. Attempts of chemical oxidation have shown the existence of nickel(III) and copper(III) in solution.

Equilibrium and structural studies of complexes with a hexadentate ligand containing amide, amine and pyridyl nitrogen donors. Crystal structures of copper(II), nickel(II) and cobalt(III) complexes

A novel potentially hexadentate ligand, 1,8-bis(2-pyridylcarbamoyl)-3,6-diazaoctane (pyctrien) has been synthesised as its tetrahydrochloride salt; its protonation constants and the stability constants of the copper(II) and nickel(II) chelates have been determined by potentiometry. Amide group deprotonation permits the formation of [MLH−1]+ and [MLH−2] species in all cases, whereas the detection of the neutral or the protonated species depends on the nature of the metal ions. The solid complexes of copper, nickel and cobalt with the neutral and the deprotonated ligand have been synthesised and characterised by IR and UV–VIS spectroscopy. The amidic groups are coordinated through the oxygen atoms in all solid complexes [ML](ClO4)2 (M = Cu2+, Ni2+ and Co2+). The complexes obtained with the deprotonated forms of the ligand imply the coordination through the nitrogen atoms of the amidic groups. In the cobalt compound, the coordination of the six nitrogen donor atoms leads to the spontaneous oxidation of Co(II) into Co(III); thus, NMR spectroscopic investigations show that this complex has an α-cis configuration. X-Ray crystal determination has shown that [CuLH−1(H2O)](ClO4) is square pyramidal with a water molecule fixed in the apical position, one picolinamide moiety remaining uncoordinated (in agreement with ESR studies), whereas [NiLH−2] and [CoLH−2](ClO4)0.75Cl0.25 are both octahedral with the two pyridine rings in cis-positions.