Sylvain Bernès

Coordination compounds of thiabendazole with main group and transition metal ions

Abstract We report LiI, NaI, KI, PbII, CoII, NiII, CuII, ZnII, CdII and HgII coordination compounds derived from thiabendazole [2-(4′-thiazolyl)benzimidazole (tbz)]. The compounds were characterised by analytical and spectroscopic techniques. NMR studies of diamagnetic compounds were performed in solution. X-ray diffraction analysis of NaI, PbII, CoII, NiII, CuII and CdII complexes showed that tbz stabilises bis- and tris-chelated coordination compounds. In solution and in solid state the ligand coordinates to the metal ions through the imidazolic and thiazole nitrogen atoms regardless of the nature of the metal ion.

Molecular architecture of copper(I) thiometallate complexes. Example of a cubane with an extra face, (NPr4)3[MS4Cu4Cl5] MMo, W)

Abstract Thiometallates MS 4 2− (M  Mo, W) form with copper(I) heterobimetallic complexes which are interesting because of the versatility of the structural types obtained. The various structures obtained by addition of copper(I) to MS 4 2− are described and illustrated by examples recently reported in the literature. The synthesis and structural characterization of (NPr 4 ) 3 [MS 4 Cu 4 Cl 5 ] are given together with the connections which exist between ‘open’ and ‘closed’ cubane structures.

Synthesis, X-ray and spectroscopic characterisation of chromium(III) coordination compounds with benzimidazolic ligands

Abstract The syntheses and characterisation of chromium(III) complexes with tris(2-benzimidazolylmethyl)amine (ntb), 2-guanidinobenzimidazole (2gb), 2,6-bis(2-benzimidazolyl)pyridine (bbimpy) and 2-(2-pyridyl)benzimidazole (2pb), of composition [Cr(ntb)Cl2]Cl·4.5H2O (1), [Cr(2gb)3]Cl[ZnCl4]·CH3OH (2), [Cr(2gb)3]Cl3·4H2O (3), [Cr2(2gb)4(μ-OH)2](ClO4)4·5H2O (4), [Cr(bbimpy)Cl3] (5) and [Cr(2pb)2Cl2]Cl·C2H5OH·0.5H2O (6) are presented. The compounds are obtained from Cr(III) in alcoholic solution, or a Cr(II) aqueous acidic solution. The latter were carried out under air-free conditions. The reaction of 2gb with Cr(II) in aqueous solution yielded a dinuclear compound. The X-ray crystal structures of 1 and 4 are discussed.

Supramolecular structures of metronidazole and its copper(II), cobalt(II) and zinc(II) coordination compounds

In this work we present the synthesis and structural and spectroscopic characterization of Cu(II), Co(II) and Zn(II) coordination compounds with the antibiotic metronidazole ([double bond]emni). Coordination to metal ions is through its imidazolic nitrogen, while the hydroxyethyl and nitro groups act as supramolecular synthons. [Co(emni)(2)Br(2)], and [Zn(emni)(2)X(2)] (X(-)=Cl, Br) stabilize zig-zag chains, and a 2D supramolecular structure is formed by inter-chain contacts through inter-molecular hydrogen-bonding. Pleated sheet or layers are formed by [Co(emni)(2)Cl(2)] and [Cu(emni)(2)Cl(H(2)O)](2)Cl(2), respectively. The dinuclear Cu(II) compound [Cu(emni)mu(O(2)CMe)(2)](2) gives a one-dimensional zig-zag arrangement. The contribution of metal ions in metronidazole coordination compounds is shown in the stabilization of the different aggregate structures.

A dicopper complex with distant metal centers. Structure, magnetic properties, electrochemistry and catecholase activity.

The crystal structure and magnetic properties of a dinuclear copper(II) complex of the ligand [2,8-dimethyl-5,11-di-(dimethylethyleneamine) 1,4,5,6,7,10,11,12-octahydroimidazo [4,5-h] imidazo [4,5-c] [1,6]diazecine] dimeim have been investigated. Also, its catecholase activity has been explored in different solvent mixtures: MeCN/H2O and OH/H2O, each at several pH values. In CH3OH/H2O, where the activity was superior, the optimal pH value for the catalytic activity was found to be lower than in CH3CN/H2O. The study of the complexs electrochemical behavior (cyclic voltammetry) which was also investigated in these various media, revealed that although an increase in pH in both solvent mixtures results in an increase both in Me oxidizing power (E(1/2)) and reversibility (ipa/ipc) the change of solvent system seems to be a more influencing factor. The superior catalytic activity found in MeOH/H2O pH=8.0, is associated with a significantly more reversible behavior displayed in this medium. Potentiometric determination of the overall formation constant and three successive pKas for the complex, suggest the formation of stable hydroxo complexes which could be the catalytically active species.

(S)-4-Isopropyl-5,5-dimethyl-1,3-oxazolidinethione as chiral auxiliary for the intramolecular sulfur transfer in α,β-unsaturated N-acylimides, promoted by NbCl5

Abstract The 1,3-oxazolidinethione 4 has been synthesized from ( S )-valine and used in the intramolecular sulfur transfer in its N -enoyl derivatives in the presence of NbCl 5 as catalyst, which, moreover, works as an indicator of the course of the reaction. The adducts have subsequently been transformed into the corresponding β-mercapto esters by action of Sm(OTf) 3 in methanol.

Heterobimetallic aggregates of copper(I) with thio-tungstate and -molybdate. Cation effect in aggregation of MS4Cu4Cl4 units, a crystallographic study

Reaction of [MS4]2–(M = Mo or W) with CuCl in dichloromethane or acetonitrile gives a new set of bimetallic compounds isolated with various geometries for the same 1:4:4 M:S:Cu composition. Crystals of [NBu4]2[MoS4Cu4Cl4]1a are tetragonal, space group I/m, a= 13.343(5), c= 14.113(2)A, Z= 2, R= 0.058. The crystal structure reveals discrete [MoS4Cu4Cl4]2– anions separated in the lattice by [NBu4]+ cations. The isostructural tungsten homologue 1b was isolated and characterized: space group I/m, tetragonal, a= 13.342(4), c= 14.106(5)A. The structure of [PPh4][NPr4][MoS4Cu4Cl4]2 consists of a dimeric aggregate: monoclinic, space group P21/n, a= 9.962(8), b= 36.951(5), c= 13.114(3)A, β= 105.71(6)°, R= 0.056. The salt [NPr4]2[WS4Cu4Cl4]3b is polymerized through linear chains. Crystals are triclinic, space group P, a= 10.283(1), b= 13.925(1), c= 15.245(1)A, α= 110.32(1), β= 90.64(1), γ= 102.49(1)°, Z= 2, R= 0.031. The isostructural molybdenum compound 3a was also characterized: triclinic, a= 10.275, b= 13.961, c= 15.270 A, α= 110.57, β= 90.70, γ= 102.30°. The arrangements of the mono-, di- and poly-meric aggregates in the lattice are discussed in terms of the size of the counter anion. For compounds 1b and 3a only the cell dimensions were determined.

Synthesis, X-ray and NMR characterisation of cobalt(III) coordination compounds with 2-guanidinobenzimidazole

Abstract The synthesis and characterisation of cobalt(III) coordination compounds with 2-guanidinobenzimidazole (2gb), namely [Co(2gb)3]Cl2(NO3)·H2O, [Co(2gb)3]Cl(NO3)2·H2O, [Co(2gb)3]Cl3·3H2O and [Co(2gb)3](Cl3CCOO)3·H2O, are presented. The compounds with the 2-guanidinobenzimidazole ligand were synthesised from [Co(NH3)4CO3]NO3 or Na3[Co(CO3)3]·3H2O or from cobalt(II) chloride. 1H, 13C and 2D NMR spectra together with the X-ray diffraction data for the distorted octahedral [Co(2gb)3]3+ cation showed that only the mer isomer was formed.

Conversion of [Pt(SRf)2(PPh2 −n(C6F5)n+ 1)2](n= 0 or 1, RfC6HF4-4) through carbon–fluorine bond activation to [Pt(SRf)2(1,2-C6F4(SRf)-(PPh2))] and chiral [Pt(SRf)2(1,2-C6F4(SRf)(PPh(C6F5)))]

Treatment of trans-[PtCl(2)(PPh(2 - n)(C(6)F(5))(n + 1))(2)](n = 0 or 1) with Pb(SC(6)HF(4)-4)(2) yields a mixture of monometallic cis/trans [Pt(SC(6)HF(4)-4)(2)(PPh(2 - n)(C(6)F(5))(n + 1))(2)], thiolate-bridged bimetallic cis/trans [Pt(2)(mu-SC(6)HF(4)-4)(2)(SC(6)HF(4)-4)(2)(PPh(2 - n)(C(6)F(5))(n + 1))(2)] and [Pt(SC(6)HF(4)-4)(2)(1,2-C(6)F(4)(SC(6)HF(4)-4)(PPh(2 - n)(C(6)F(5))(n))].

Interaction between Glyglu and Ca2+, Pb2+, Cd2+ and Zn2+ in solid state and aqueous solution.: Crystal structures of poly[aqua-1,2-κ-O-di[lead(gly-gluH)]bis(perchlorate)] and poly[bisglycylglutamic-cadmium(II) tetrahydrate]

Abstract Glycylglutamic acid (GE H 2 ) is a peptide usually present in calcium binding sites. The interaction between the peptide and the cations Ca 2+ , Pb 2+ , Cd 2+ , and Zn 2+ in aqueous solution and in the solid state is described. Six compounds were isolated with different protonation states of the ligand. Potentiometric equilibrium studies, 13 C and 111 Cd solid state CP MAS NMR and IR spectroscopy were performed. Two crystal structures are reported: [Pb(GE H )(H 2 O) 1/2 ]ClO 4 and [Cd(GE H ) 2 ]·3H 2 O. Both constitute 3D polymers, where only carboxylate groups are coordinated to the cations. The crystalline lead compound shows a hemidirected coordination sphere due to its stereochemically active lone pair. In deprotonated derivatives, it is possible to assign a metal-amino interaction to a far IR signal (340–370 cm −1 ).