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International audience; A general synthetic approach to a novel range of semirigid bifunctional chelating agents (BCAs) that include an aromatic ring and a triazolyl moiety in the chelating unit has been investigated for the fac‐[M(CO)3]+ core (M = 185/187Re or 188Re). The strategy includes the facile preparation of these N2O ligands bearing various functionalized arms (carboxylate, terminal alkyne, aromatic amine). The reaction of commercial [Re(CO)5Cl] {or a freshly prepared [Re(OH2)3(CO)3]+ precursor} with our BCAs in methanol led to the formation of stable neutral tricarbonylrhenium complexes of general formula [Re(CO)3(L)] (LH = 5, 10, 11) in high yields. These compounds were characterized by IR and NMR spectroscopy, mass spectrometry, electrochemistry, and X‐ray crystallography for [Re(CO)3(5–H)] and [Re(CO)3(11–H)] as well as by DFT calculations. The analogous rhenium‐188 complexes [188Re(CO)3(5)] and [188Re(CO)3(11–H)] were also prepared, in acceptable to excellent yields, by the reaction of 5 or 11 with the fac‐[188Re(OH2)3(CO)3]+ precursor in methanol at 80 °C. The structural identities of the radioactive complexes were assessed by HPLC studies. The good affinity of these click ligands for the ReI core combined with the ease of their derivatization make this chelating system promising for the conception of target‐specific radiopharmaceuticals for therapeutic purposes.

International audience; Guanine radical detection was carried out by a new convenient and efficient method coupling electron paramagnetic resonance spectroscopy and indirect electrooxidation of guanine in different biological environments, from the free nucleotide to several types of DNA substrates. Compared to the widely used photoirradiation method, this method appeared more selective in the choice of the electrochemical mediator. Carried out in presence of a ruthenium mediator and PBN as spin trap, this method revealed two types of EPR spectra depending of the environment of the guanine radical. Both EPR spectra show the trapping of the neutral guanine radical G(−H)• obtained after fast deprotonation of the radical cation G•+. However, they differ by the atom where the trapped radical is centered. This difference highlights the structural dependency of the environment on the nature of the radical formed. This work gave the evidence of an innovative method to detect in situ the guanine radical.

The electrocarboxylation of chloroacetonitrile (NC–CH2–ClRCl) mediated by [CoIIL2]2+ (L = terpyridine) was investigated by cyclic voltammetry. Electrochemical studies under argon atmosphere showed that the monoelectronic reduction of [CoIIL2]2+ yielded a Cobalt(I) complex which after the loss of a terpyridine ligand reacted with chloroacetonitrile. The oxidative addition of chloroacetonitrile on [CoIL]+ gave an alkylCobalt(III) complex [R–CoIIIL]2+ which was reduced into an alkylCobalt(II) complex, highly unstable and decomposed into an alkyl anion and a Cobalt(II) complex. Under carbon dioxide atmosphere, Cobalt(I) complex was shown to be unreactive towards CO2 but CO2 insertion was observed in the alkylCobalt(III) complex [R–CoIIIL] 2+ giving probably a CO2 adduct [R–CoIIIL(CO2)]2+. This adduct presented a strong adsorption at the carbon electrode and was reduced at potential less cathodic than the one of alkylCobalt(III) complex. After reduction, the carboxylate RCO2− (NC–CH2–CO2−) was released and a catalytic bielectronic carboxylation of chloroacetonitrile took place. Controlled potential electrolyses confirmed the catalytic process and gave for cyanoacetic acid faradic yields up to 60% under low overpotential conditions.

Disodium and ditetraphenylphosphonium salts of 2,4-bis(cyanamido)cyclobutane-1,3-dione, Na2(2,4-NCNsq) · 2H2O (1) and (Ph4P)2(2,4-NCNsq) · 4H2O (2) have been synthesized and used to prepare three nickel(II) complexes: [Ni(Him)4(2,4-NCNsq) · 2H2O]n (3), [Ni(Him)3(H2O)(2,4-NCNsq) · H2O]n (4) and [Ni(Him)2(H2O)2(2,4-NCNsq) · 3H2O]n (5). Compounds 1–5 have been synthesized and characterized by electronic absorption and IR spectroscopies and by electrochemical studies. The structures of the salt 2 and of the complexes 3–5 have been determined by X-ray crystallography. The dianion of 2 presents a centro-symmetric square planar structure with two NCN functions deviated from the ring plane by an angle of 20.6°. Complexes 3–5 are polynuclear nickel(II) compounds containing 2,4-NCNsq2− bridging ligands. These ligands are coordinated by the nitrile nitrogen atoms of the cyanamido functions and lie in cis (complex 4) or trans (complexes 3 and 5) positions in the coordination sphere of the nickel(II). The magnetic properties of the three complexes have been investigated in the 2–300 K temperature range (μeff = 2.79–3.34 μB for 3, 2.76–3.25 μB for 4 and 3.14–3.46 μB for 5). Their redox properties are discussed and compared to those of the free 2,4-NCNsq2− dianion.

Three palladium(II) complexes have been synthesized, using 3,4-bis(cyanamido) cyclobutane-1,2-dione dianion (3,4-bis(cyanamido)squarate or 3,4-NCNsq 2− ): [Pd(en)(3,4-NCNsq)] · 1.5H 2 O ( 1 ) (en=1,2-diaminoethane), [Pd(en)(3,4-(NC(O)NH 2 )sq)] · 0.5H 2 O ( 2 ) and K 3 Na[Pd 2 (3,4-(NCN) 2 sq) 4 ] · 5H 2 O ( 3 ). Complex 1 has been characterized by elemental analysis, IR and 13 C NMR spectroscopies. Complexes 2 and 3 have been characterized by single-crystal X-ray diffraction. In complex 2, the unusual hydration of the cyanamido ligand was observed, it proceeds in the coordination sphere of the palladium and leads to a chelating urea squarate ligand. Complex 3 is an anionic dinuclear complex containing four bridging cyanamido squarate ligands. In complexes 2 and 3 , the 3,4-NCNsq 2− ligand (hydrated or not) is, for the first time, coordinated to the metal atom by the two amido nitrogen atoms, either in a chelating mode (complex 2 ) or in a bridging mode giving a short Pd ⋯ Pd distance of 2.8866(15) A (complex 3 ). Electrochemical studies in acetonitrile and dmf solutions have been performed on complexes 1 and 3 .

Three complexes [Ni(Him)4(3,4-NCNsq)(H2O)]·H2O 1, {[Ni2(Him)2(3,4-NCNsq)2(H2O)6]·8H2O}n2 and [Ni(tren)(3,4-NCNsq)]n3, where 3,4-NCNsq2− = 3,4-bis(cyanamido)cyclobutane-1,2-dione dianion and Him = imidazole, have been synthesized and characterized by electronic absorption and IR spectroscopies. The structures of the three complexes have been determined by X-ray crystallography and, for the first time, two conformations of the ligand 3,4-NCNsq2− have been evidenced. Complex 1 consists of mononuclear entities and complexes 2 and 3 are made of infinite chains with nickel(II) atoms bridged by the bis monodentate 3,4-NCNsq2− ions. The magnetic properties of the three complexes have been investigated in the 2–300 K temperature range (μeff = 2.84 to 3.12 μB for 1, μeff = 2.32 to 3.46 μB for 2 and μeff = 2.74 to 3.13 μB for 3). Their redox properties are discussed and compared to those of the free 3,4-NCNsq2− dianion.

Cationic Re(III) complexes [ReX2(PMe3)2(biimH2)]X (where biimH2 = 2,2′-biimidazole; X = Cl, Br, I) are prepared by phosphine displacement in the corresponding PPh3 complexes in the presence of excess PMe3. The N–H protons of co-ordinated biimidazole are moderately acidic and the monodeprotonated form [ReX2(PMe3)2(biimH)] is isolated after addition of one equivalent of NaOCH3. Crystal structures determined for two compounds of each series reveal that strong hydrogen bonding takes place between the N–H groups and the halide counter-ion in the cationic complexes, whereas the neutral molecules crystallise as dimeric units tightly associated via two complementary N–H⋯N interactions. The acidities of the two N–H groups of [ReCl2(PMe3)2(biimH2)]+ in CH2Cl2 are estimated from UV-visible spectra and found to correspond approximately to those of formic acid and 3-chlorophenol, respectively. Electrochemical data on the series of PPh3 and PMe3 complexes with the three halides indicate that the redox potentials of both the metal and the counter-ion are affected by ion pairing in solution.

The crystal structures of two copper(II) complexes of croconate violet (3,5-bis(dicyanomethylene)cyclopentane-1,2,4-trionate=L2−) have been determined by X-ray methods. Complex 1 consists of mononuclear [CuL2(H2O)2]2− ions, potassium cations and two crystallisation water molecules. Complex 2 consists of mononuclear [CuL3]4− ions, (NBu4)+ cations and one half crystallisation water molecule. In these two complexes, the ligand is coordinated in a chelating mode by two adjacent oxygen atoms. The electrochemical behaviour of these complexes is discussed and compared to that of the free croconate violet.

The reaction of copper(II) ions with the 2,4-bis(dicyanomethylene)cyclobutane-1,3-dione dianion (2,4-dcmsq2−), a pseudo-oxocarbon derived from squaric acid in which two carbonyl oxygen atoms have been substituted by dicyanomethylene groups C(CN)2, leads to many complexes according to the preparative scheme. The complex [Cu(2,4-dcmsq)(H2O)4]n has been synthesized and characterized by single-crystal X-ray diffraction. The structure consists of a chain of copper atoms bridged by the ligand with short CuN bonds. Spectroscopic and structural characterizations of the product are compared with those of the previously described [Cu(2,4-dcmsq)(H2O)4·2H2O]n.

Three complexes [Cu2(PPh3)4(MeCN)2(cis-(NCN)2sq)]·MeCN 1, {[Cu2(dien)2(cis-(NCN)2sq)2]·5H2O}n2 and [Cu(tren)(cis-(NCN)2sq)] 3 where [cis-(NCN)2sq]2− = 3,4-bis(cyanamido)cyclobutane-1,2-dione dianion, have been synthesized and characterized by electronic absorption and IR spectroscopies. The structures of the three complexes have been determined by X-ray crystallography. Complex 1 is present as a dinuclear copper(I) compound. Complex 2 is made of infinite chains with copper(II) atoms bridged by the bis monodentate [cis-(NCN)2sq]2− ion. In the mononuclear complex 3 the co-ordination of the cyanamido group unusually occurs via the amido nitrogen and not by the nitrile group; this is accompanied by an important distortion of the co-ordinated cyanamido group. The co-ordination mode of the cyanamido moiety is discussed in regard to IR data and crystallographic results.

The compound (Ph4P)2(trans-cdcb)·2H2O (trans-cdcb2- = 2,4-bis(dicyanomethylene)-cyclobutane-1,3-dione dianion) has been synthesized and characterized by X-ray crystallography. Crystal data: triclinic, space group P1, a = 10.829(2) Å, b = 11.297(2) Å, c = 11.515(2) Å, α = 79.61(1)°, β = 68.54(1)°, γ = 63.49(1)°, V = 1172.9(4) Å3, Z = 1, R = 0.036, Rw = 0.047. With the dianion as a ligand, two complexes have been obtained and characterized by X-ray crystallography, UV-visible spectroscopy, and electrochemistry. The copper(II) complex [Cu(trans-cdcb)(H2O)4·2H2O]n consists of polymeric chains with copper atoms bonded to two of the nitrile groups of the ligand. Crystal data: monoclinic, space group P21/c, a = 9.6366(6) Å, b = 7.1292(3) Å, c = 10.7018(6) Å, β = 99.603(4)°, V = 724.92(7) Å3, Z = 2, R = 0.026, Rw = 0.041. The copper(I) complex[Cu2(trans-cdcb)(CH3CN)4·2CH3CN]n consists of polymeric chains with copper atoms bonded by all the four nitrile groups of the ligand. Crystal data: monoclinic, space group P21/n, a = 10.654(2) Å, b = 8.736(1) Å, c = 14.654(3) Å, β = 109.01(2)°, V = 1291.3(9) Å3, Z = 2, R = 0.037, Rw = 0.041. In CH3CN solution, the copper complexes are dissociated. Moreover, copper(II) is reduced into copper(I) by the dianion. Electrochemistry in the solid state (polymer coated electrode) showed the redox transitions of the different compounds.Key words: pseudo-oxocarbons, X-ray diffraction, copper(II) complex, copper(I) complex, electrochemical behaviour.

International audience; The polynuclear manganese(II) complex of L-dihydroorotic acid has been synthesized and characterized by X-ray crystallography, UV-visible spectroscopy, and magnetic susceptibility measurements. Crystal data: triclinic, space group P1 bar , a = 4.7239(5) , b = 7.902(1) , c = 10.552(2) , = 105.80(1), = 98.864(7), = 104.69(1), V = 355.9(1) D 3, Z = 1, R = 0.035, Rw = 0.028. This complex consists of polymer chains of manganese atoms that are bound together via carboxylate bridges with a Mn . . .Mn distance in the chain of 4.724 D . The radical scavenging properties of the complex have been evaluated by ESR spectroscopy and cyclic voltammetry methods and compared to those of vitamin E and BHT (2,6-di-tert-butyl-4-methylphenol).Key words: orotic acid, L-dihydroorotic acid, manganese(II) complex, antioxidative properties.; Le complexe du manganèse(II) et de l'acide L-dihydroorotique a été synthétisé et caractérisé par spectroscopie UV-visible, susceptibilité magnétique et par diffraction des rayons X. Données cristallographiques : triclinique, groupe d'espace P 1 bar , a = 4.7239(5) D , b = 7.902(1) D , c = 10.552(2) D , α = 105.80(1)°, β = 98.864(7)°, γ~= 104.69(1)°, V = 355.9(1) D 3, Z = 1, R = 0.035, Rw = 0.028. Ce complexe se présente comme une chaine polymérique d'atomes de manganèse liés entre eux par des ponts carboxylate, la distance Mn . . .Mn étant de 4.724 D . Les propriétés antioxydantes de ce composé ont été évaluées par RPE et voltammétrie cyclique et comparées à celles de la vitamine E et du BHT (2,6-di-tert-butyl-4-methylphenol).Mots clés : acide orotique, acide L-dihydroorotique, complexe du manganèse(II), propriétés antioxydantes.

Reaction of copper(II) ion with 3,4-bis(dicyanomethylene)cyclobutane-1,2-dione dianion (cdcb2–) led to a copper(I) complex, [{Cu2(cdcb)(MeCN)2}n]. The crystal structure of this first complex of cdcb has been determined; it consists of layers of Cu2(cdcb)(MeCN)2 units parallel to the ab planes. The redox system of this complex, investigated by electrochemistry and ESR spectroscopy, is formed by the dianion, the radical anion, the neutral species of cdcb and the CuI–CuII system.

The crystal structures of cobalt(II) complexes of croconate [CoL1(H2O)3] 1 (L1 = C5O52–) and croconate violet K2[CoL22(H2O)2]·2H2O 2 [L2 = 3,5-bis(dicyanomethylene)cyclopentane-1,2,4-trionate] have been determined. Complex 1 consists of infinite zig-zag chains constituted by one metal atom, one croconate acting as a bridge and three water molecules. Moreover these chains, parallel to the c axis, are stacked with metal–metal distances of 7.9891(3) A inside a chain and 5.0035(6) A between chains. Complex 2 consists of dianionic and mononuclear entities in which the ligand is O-co-ordinated. The magnetic properties of 1 and 2 have been investigated in the 4–300 K temperature range (µeff = 3.65 to 5.02 µB for 1 and µeff = 4.00 to 4.90 µB for 2). Their redox properties are discussed and compared to those of the free ligands.

The novel trimethylphosphine azido ruthenium(II) complex trans -Ru(N 3 ) 2 (PMe 3 ) 4 has been obtained and characterized by elemental analysis, IR and NMR spectroscopies, and electrochemistry. Its structure has been determined by single crystal X-ray diffraction methods. The complex consists of monomeric Ru(N 3 ) 2 (PMe 3 ) 4 units, in which the coordination geometry around the Ru atom is a distorted octahedron. The two azido ligand occupy trans positions and are oriented in two nearly orthogonal planes. Conversion into the cis isomer in CH 2 Cl 2 has been followed by 31 P NMR and cyclic voltammetry.

The oxidation of diacetone-L-sorbose (DAS) into diacetone-2-keto-L-gulonic acid (DAG) is a step in the synthesis of vitamin C. This oxidation was carried out electrochemically in a stirred cell with the redox couple Ni (OH)2/β-NiOOH as an electrochemical mediator. The anode was made of a current collector (nickel foam or platinized-titanium) and of a suspension of Ni(OH)2 in KOH aqueous media. The mediated electrooxidation of DAS was achieved by the Ni(OH)2β-NiOOH couple in solution which was regenerated at the current collector. This process required a two-compartment reactor but afforded high yields of chemical conversion: we obtained 96% with a 48% faradaic yield. Previous works dealing with DAS electrooxidation to DAG on nickel anode are reviewed hereafter. L'oxydation du diacetone-L-sorbose (DAS) en acide diacetone-2-ceto-L-gulonique (DAG) est une etape importante dans la synthese de la vitamine C. Cette oxydation a ete assistee electrochimiquement par le couple redox Ni(OH)2/β-NiOOH. L'anode etait constituee par un collecteur de courant, soit en mousse de nickel soit en titane platine, et une suspension de Ni(OH)2 en milieu KOH. C'est le β-NiOOH qui assurait l'oxydation du DAS et qui etait regenere a l'anode. Ce procede a necessite un reacteur a deux compartiments mais a conduit a des taux eleves de conversion: nous avons obtenu un rendement chimique de 96% avec un rendement faradique de 48% ont ete obtenus. Nous comparons ici ces resultats avec ceux de la litterature.

International audience; Effect of copper ions on the electrochemical behaviour of an alkylaminethiol monolayer has been studied by electrochemical impedance spectrosocpy. RAMAN experiment shows the effective adsorption of receptor onto the gold surfaces. The study of Nyquist plot shows that the gold/monolayer/electrolyte interface can be described by a serial combination of two R, CPE electrical circuits. In the presence of increasing amounts of copper, the Nyquist plots at low frequencies were modified showing an increase of the resistance of the second R, CPE electrical circuit. Moreover, this increase of resistance varies linearly with the amounts of copper ions added in solution from 10−8 mol*L−1 to 10−5 mol*L−1.

Three complexes of palladium and 3,4-diaminothiophene (L) have been synthesized: [PdL2]Cl2·4H2O (1), PdLCl2(2) and PdLBr2(3). These complexes can be electrochemically oxidized and yield thin-film polymers. One of them, derived from 3, gives a material which can be doped with palladium particles by electroreduction. Crystal data for 1, C8H20Cl2N4O4PdS2, are as follows: M= 441.68, monoclinic, a= 6.6206(2)A, b= 9.8983(1)A, c= 13.2854(1)A, β= 94.47(2)°, V= 868(1)A3, space group P21/c(no. 14), Z= 4, R= 0.0456 and Rw= 0.0677. The ligand is bound to the metal by the amino substituents. The complexes are stacked in parallel columns with short stacking distances (3.27 A).

Reaction of excess CNCH2SiMe3(L) with CuX2·nH2O (X=NO3−, n=3; ClO4−, n=6) in THF gives the CuI complexes [CuL4]NO3 (1) and [CuL4]ClO4 (2). When CuCN is used as starting material, complex 3, Cu(L3)CN, C4H10O·3H2O, is obtained. Immediate reduction occurs with AgNO3 precipitating metallic Ag. Reactions with MnCl2·6H2O and Mn(NO3)2·6H2O in THF produce two new compounds which analyze as MnL4Cl2·4H2O (6) and MnL2(NO3)2·H2O (7). When excess p-tolylsulfonylmethylisocyanide (L′) is reacted with Cu(NO3)2, the mixed-valence CuICuII complex Cu2L′6(NO3)3 (5) is precipitated, while using CuCN gives the CuI dimer Cu2L′4(CN)2 (4). In analogous conditions the manganese complex MnL′2(NO3)2·C3H6O·3H2O (8) is precipitated. All these complexes have been isolated, characterized by IR, NMR for diamagnetic species, magnetic susceptibilities, EPR measurements and electrochemical analyses. Influence of the two substituents is discussed.

The electron rich cluster Ru[sub 3]([mu][sub 3]-[eta][sup 2]-P(C[sub 6]H[sub 5])(C[sub 5]H[sub 4]N))([mu]-P(C[sub 6]H[sub 5])[sub 2])[sub 3](CO)[sub 6] (9) is prepared by incorporation of diphenylphosphido groups into the ligand shell of triruthenium complexes that already contain a face-bridging phosphido-pyridyl ligand. The two precursors are (i) the known acyl complex Ru[sub 3]([mu]-C(O)(C[sub 6]H[sub 5]))([mu][sub 3]-[eta][sup 2]-P(C[sub 6]H[sub 5])(C[sub 5]H[sub 4]N))(CO)[sub 9] (1), which reacts with 3 equiv of diphenylphosphine in refluxing methylcyclohexane to produce 9 in 75% yield, and (ii) the complex Ru[sub 3]([mu][sub 3]-[eta][sup 2]-P(C[sub 6]H[sub 5])(C[sub 5]H[sub 4]N))([mu]-P(C[sub 6]H[sub 5])[sub 2])(CO)[sub 6]([mu]-CO)[sub 2] (4), which also leads to 9 via reaction with 2 equiv of diphenylphosphine (yield 75%). The structure of compound 9 has been determined by X-ray diffraction. The structure consists of a triangular array of ruthenium atoms capped by a phenylpyridylphosphido ligand as referred to the antecedent species. Each Ru-Ru edge is supported by a diphenylphosphido group occupying equatorial coordination sites. The environment of each Ru atom is completed by two terminal carbonyl ligands. Even though this trinuclear species contains 50 cluster valence electrons, the three Ru-Ru bond distances are equivalent within experimental error. An electrochemical study carried out in CH[sub 2]Cl[sub 2] reveals that the compound undergoesmore » two well-defined reversible one-electron oxidations at E[sub 1/2] = 0.16 V and E[sub 1/2] = 0.53 V, respectively (vs Ag/AgCl, KCl 0.1 M, H[sub 2]O). The unusual closed geometry of 9 is rationalized in terms of molecular orbital calculations of extended Hueckel type and compared with that of the isostructural 48-e closed complex 4 and the isoelectronic 50-e open cluster Ru[sub 2]([mu][sub 3]-[eta][sup 2]-P(C[sub 6]H[sub 5])(C[sub 5]H[sub 4])([mu]-P(C[sub 6]H[sub 5])[sub 2]))(CO)[sub 9] (5). 32 refs., 6 figs., 6 tabs.« less

International audience; In this experiment, the concentrations of copper and zinc in brass are obtained by two methods. This experiment does not require advanced instrumentation, uses inexpensive chemicals, and can be easily carried out during a 3-h upper-level undergraduate laboratory. Pedagogically, the basic concepts of analytical chemistry in solutions, such as pH, solubility, complexation, and redox reactions, are illustrated. In addition, this experiment can be used to introduce the science of alloys. Oxidation of brass pieces by concentrated nitric acid yields a solution of Cu2+ and Zn2+ cations. The first method consists in an acid−base titration of Cu2+ and Zn2+ cations by sodium hydroxide. The successive precipitations of the corresponding hydroxide complexes are observed in a pH titration curve that allows the calculation of the concentrations of Cu2+ and Zn2+ and thus the brass composition. The second method is based on complexometric titrations with and without the competition between complexing agents, steps 1 and 2, respectively. In step 1, the copper and zinc together are titrated by EDTA. In step 2, the addition of sodium thiosulfate masks the Cu2+ and the titration by EDTA leads to the determination of Zn2+ concentration. Cu2+ concentration and brass composition are readily obtained.

Squaric (H2Sq) and croconic (H2Croc) acid (H2A) react with [PtL4]2+ (L = ammonia or L2 = ethylenediamine) to yield complexes formulating as [PtL4](HA)2. The crystal structure of the complexes [Pt(en)2](HSq)2 and [Pt(en)2](HCroc)2 have been determined using X-ray diffraction techniques. Oxidation of platinum occurred in the course of the same reaction and complexes of [PtL4Cl2]A were obtained. The X-ray determination of the structure of [Pt(NH3)4Cl2]Sq is reported. Electrochemical measurements have been performed in the solid state to support the results obtained during the oxidation process.

International audience; From the 2,4-bis(cyanamido)cyclobutane-1,3-dione dianion (2,4-NCNsq2−), two copper complexes [Cu2(PPh3)4(PhCN)2(μ-2,4-NCNsq)] · PhCN (1) and [Cu(dien)(μ-2,4-NCNsq) · H2O]n (2) have been synthesized and characterized by IR and electronic absorption spectroscopies. Their structures have been determined by X-ray crystallography. Complex 1 is a dinuclear copper(I) compound with a 2,4-NCNsq2− ligand bridging two copper atoms through the nitrile nitrogen atoms. Complex 2 appears as a 3D network constituted of copper(II) atoms bridged by 2,4-NCNsq2− dianions. This complex presents an unexpected coordination mode of the bis(cyanamido) ligands which are both coordinated via the nitrile functions and via the amido nitrogen atoms of the NCN groups.

The acidity and dimerisation constants are determined for [Pd(L)(H2O)2]2+ [L=2-(aminomethyl)pyridine and N′-methyl-2,4′-bipyridin-3-ylium

The effects of propantheline bromide and an aluminum hydroxide/magnesium hydroxide suspension on absorption of ranitidine were evaluated in 12 healthy volunteers according to a Latin square design. Ranitidine 150 mg was administered alone, with 30 ml antacid or preceded by 15 mg propantheline. Ten serum samples were obtained over 12 hours during each treatment period for measurement of ranitidine concentration. The antacid had no significant effect on ranitidine absorption, but propantheline increased the relative bioavailability of ranitidine by 22%. In addition, there was a trend, although not statistically significant, for propantheline to increase the maximum ranitidine serum concentration and the time to maximum serum concentration. Ranitidine can be administered concomitantly with the evaluated doses of antacid and propantheline without a clinically significant alteration in its absorption.