Ternary complexes of cimetidine and phenobarbital with Cu(II) in methanolic solution

The formation constants of the binary complexes Cu(CM)²⁺ and Cu(CM) ₂ ²⁺ as well as those of the ternary complexes Cu(CM)L ⁺ and Cu(CM)₂ L ⁺ (CM=Cimetidine=N-Cyano-N-methyl-N[(5-methyl-1H-imidazol-4-yl)methyltioethyl]-guanidine; HL=Phenobarbital=5-ethyl-5-phenyl-barbituric acid) have been determined in 0.1 and 1.0 mol dm^–3 NaClO₄ methanol solutions at 25±0.2°C. The values of logX, log _stat.., and logK confirm the stability of the ternary complexes.

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Ternäre Komplexe von Cimetidin und Phenobarbital mit Cu(II) in methanolischer Lösung

Zusammenfassung Die Stabilitätskonstanten der binären Komplexe Cu(CM)²⁺ und Cu(CM) ₂ ²⁺ sowie die der ternären Komplexe Cu(CM)L ⁺ und Cu(CM)₂ L ⁺ (CM=Cimetidin=N-Cyan-N-methyl-N-[(5-methyl-1H-imidazol-4-yl)methylthioethyl]-guanidin; HL=Phenobarbitalum=5-Ethyl-5-phenyl-barbitursäure) wurden in 0.1 und 1.0M Lösungen von NaClO₄ in Methanol bei 25±0.2°C bestimmt. Die Werte von logX, log _stat. und logK bestätigen die Stabilität der ternären Komplexe.

     

Nickel(II), copper(II) and zinc(II) complexes withN-phenylglycine in water-methanol solution

The complex equilibria of the Ni(II), Cu(II), and Zn(II) complexes withN-phenylglycine have been studied by computer analysis of potentiometric data. The mode of coordination has been established by¹H NMR and IR studies.

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Nickel(II), Kupfer(II) und Zink(II)-Komplexe mitN-Phenylglycin in Wasser-Methanol-Lösung

Zusammenfassung Anhand der Computer-Analyse von potentiometrischen Daten wurden die Bildungsgleichgewichte von Nickel(II), Kupfer(II) und Zinc(II)-Komplexen mitN-Phenylglycin untersucht. Zur Bestätigung des Koordinationstyps wurden¹H-NMR- und IR-Messungen vorgenommen.

     

Novel five- and six-coordinate zinc (II), cadmium (II) and mercury(II) complexes of macrocyclic ligands

Summary Complexes of 2,6-dipicolinic acid hydrazide, DPH, with Zn^II, Cd^II and Hg^II have been prepared and characterized by elemental analysis, i.r. and electronic spectra and by electrical conductance measurements. The ligand is terdentate, having coordination sites at two deprotonated amide-nitrogen and pyridine-nitrogen atoms. The Zn^II and Hg^II complexes are pentacoordinate whereas the Cd^II complexes are hexacoordinate and have trigonal bipyramidal and pseudooctahedral stereochemistries, respectively. The Zn, Cd and Hg ions induce cyclization of DPH complexes upon reaction with-diketones. The complexes of macrocyclic ligands so formed have the same stereochemistries as those of DPH.     

Polymetallic complexes: Part VI. Schiff base complexes of cobalt(II), copper(II), nickel(II), zinc(II), cadmium(II) and mercury(II)

Summary The doubly bidentate ON-NO donor Schiff base, prepared from salicylaldehyde and 4,4-diaminodiphenylmethane forms complexes with 11 metal: ligand stoichiometric ratios. The cobalt(II), copper(II) and nickel(II) complexes exhibit subnormal magnetic moments. All the six complexes possess high melting points and are sparingly soluble in common organic solvents. A dinuclear octahedral structure is proposed for the cobalt(II), copper(II), nickel(II) and zinc(II) complexes and a dinuclear tetrahedral configuration is suggested for the cadmium(II) and mercury(II) complexes on the basis of analytical, conductance, magnetic susceptibility, molecular weight, i.r. and electronic spectral data.     

Mixed metal complexes in solution. Thermodynamic and spectrophotometric study of copper(II)-citrate heterobinuclear complexes with nickel(II), zinc(II) or cadmium(II) in aqueous solution

Summary A thermodynamic study of Cu^II–M^II-citrate (M^II=Ni^II, Zn^II or Cd^II) ternary systems has been performed by means of potentiometric measurements of hydrogen ion concentration at different temperatures (10, 25, 35 and 45°C) and at I=0.1 mol dm^–3 (KNO₃).The different binary and ternary systems involved have been further characterized by visible spectra and by calculating the spectra ( versus ) of all the Cu^II complexes.The thermodynamic data suggest strong entropic stabilization for the species under discussion. As regards the visible spectral characteristics of Cu^II(d-d transitions), the substitution of one Cu^II ion in the dimer [Cu₂(cit)₂H_–2]^4– by Ni^II or Zn^II to form heterobinuclear [CuM(cit)₂H_–2]^4– complexes, gives rise to a change in the visible spectrum.     

Synthesis and characterization of zinc(II), copper(II) and cadmium(II) coordination polymers with tetrachloroterephthalate-based ligands

Three complexes, namely Zn(BDC-Cl₄)(py)₃ (1), Cu(BDC-Cl₄)(py)₃ (2) and Cd(BDC-Cl₄)(py)₃ (3) (BDC-Cl₄ = 2,3,5,6-tetrachloro-1,4-benzenedicarboxylate, py = pyridine) have been synthesized. Complexes (1) and (2) have been obtained using solvothermal methods. Both have a five-coordinate geometry with two bridging monodentate tetrachloroterephthalate ligands and three pyridine ligands coordinated to the Zn(II) or Cu(II) atom. The tetrachloroterephthalate ligands bridge the adjacent Zn(II) or Cu(II) centers, giving zigzag chains. Complex (3) has also been crystallized, each Cd(II) atom is six-coordinated to three carboxylate oxygen atoms and three pyridyl nitrogen atoms. Two types of tetrachloroterephthalate ligand, featuring monodentate and bidentate carboxylates, connect the Cd(II) centers to form zigzag chains. All three complexes have been subjected to thermogravimetric analysis.     

Sulfadrug complexes of zinc(II), cadmium(II) and mercury(II)

Summary Zn^II, Cd^II and Hg^II complexes of sulfadrugs,viz., sulfathiazole, sulfadiazine, sulfamerazine and sulfamethazine were prepared and characterized by analytical and spectroscopic data. The complexes are insoluble and melt with decomposition. The drugs act as bidentate ligands yielding polymeric complexes except for the Zn^II(sulfamethazine) complex in which the drug is monodentate.     

Six-coordinate dinuclear hexaazamacrocyclic complexes of nickel(II), copper(II) and zinc(II) with tetraamide group ligands

Summary A series of 20–24 membered macrocyclic dinuclear transition metal complexes [M₂L¹X₄]-[M₂L⁴X₄] (M = Ni^II, Cu^II or Zn^II; X = Cl or NO₃) have been synthesized by template condensation of diethylenetriamine with dicarboxylic acids. The bonding and stereochemistry of the complexes have been characterized by i.r.,¹H-n.m.r., e.p.r. and electronic spectral studies, magnetic susceptibility and conductivity measurements. The Ni and Zn complexes exhibit octahedral geometry around the metal ion, whereas the Cu complexes possess a distorted octahedral geometry. Each metal ion is coordinated by two amide nitrogens and two secondary nitrogens of the diethylenetriamine moiety; the fifth and sixth coordination sites are occupied by the anions.     

Ternary complexes of copper(II), nickel(II) and zinc(II) with nitrilotriacetic acid as a primary ligand and some phenolic acids as secondary ligands

Summary The formation of ternary complexes of the MAL^3– type [where M = Cu^II, Ni^II and Zn^II ; A = nitrilotriacetic acid (NTA); L = 1-hydroxy-2-naphthoic acid (1,2 HNA) and 2-hydroxy-1-naphthoic acid (2,1 HNA)] have been studied potentiometrically in 50% v/v aqueous — ethanol (25° and µ = 0.1). Under identical conditions the binary complexes of the 1,2- and 2,1-HNA ligands have also been examined. The values of mixed ligand formation constants K_MAL have been found to be lower than K_ML (first step formation constant of binary complexes) and even less than (second step formation constant of binary complexes).     

Zinc(II), cadmium(II), mercury(II), and ethylmercury(II) complexes of phosphinothiol ligands

Neutral zinc, cadmium, mercury(II), and ethylmercury(II) complexes of a series of phosphinothiol ligands, PhnP(C6H3(SH-2)(R-3))3-n (n = 1, 2; R = H, SiMe3) have been synthesized and characterized by IR and NMR ((1)H, (13)C, and (31)P) spectroscopy, FAB mass spectrometry, and X-ray structural analysis. The compounds [Zn{PhP(C6H4S-2)2}] (1) and [Cd{Ph2PC6H4S-2}2] (2) have been synthesized by electrochemical oxidation of anodic metal (zinc or cadmium) in an acetonitrile solution of the appropriate ligand. The presence of pyridine in the electrolytic cell affords the mixed complexes [Zn{PhP(C6H4S-2)2}(py)] (3) and [Cd{PhP(C6H4S-2)2}(py)] (4). [Hg{Ph2PC6H4S-2}2] (5) and [Hg{Ph2PC6H3(S-2)(SiMe3-3)}2] (6) were obtained by the addition of the appropriate ligand to a solution of mercury(II) acetate in methanol in the presence of triethylamine. [EtHg{Ph2PC6H4S-2}] (7), [EtHg{Ph2P(O)C6H3(S-2)(SiMe3-3)}] (8), [{EtHg}2{PhP(C6H4S-2)2}] (9), and [{EtHg}2{PhP(C6H3(S-2)(SiMe3-3))2}] (10) were obtained by reaction of ethylmercury(II) chloride with the corresponding ligand in methanol. In addition, in the reactions of EtHgCl with Ph2PC6H4SH-2 and with the potentially tridentate ligand PhP(C6H3(SH-2)(SiMe3-3)) 2, cleavage of the Hg-C bond was observed with the formation of [Hg{Ph2PC6H4S-2}2] (5) and [Hg(EtHg) 2{PhP(O)(C6H3(S-2)(SiMe3-3))2}2] (11), respectively, and the corresponding hydrocarbon. The crystal structures of [Zn3{PhP(C6H4S-2)2}2{PhP(O)(C6H4S-2)2}] (1*), [Cd2{Ph2PC6H4S-2}3{Ph2P(O)C6H4S-2}] (2*), 3, 5, 6, [EtHg{Ph2P(O)C6H4S-2}] (7*), 8, 9, [{EtHg}2{PhP(O)(C6H3(S-2)(SiMe3-3))2}] (10*), and 11 are discussed. The molecular structures of 1, 2, 4, 7, and 10 have also been studied by means of density functional theory (DFT) calculations.     

Synthesis and characterization of some new nickel(II), zinc(II) and cadmium(II) complexes of quadridentate SNNS ligands

Two new quadridentate Schiff base ligands formed from 2,5-hexanedione and S-alkyldithiocarbazic acids and their nickel(II), zinc(II) and cadmium(II) complexes having the general formula [M(SNNS)] (SNNS²⁻ is the dinegatively charged ligands) have been synthesized and characterized by elemental analysis and magnetic and spectroscopic methods. The Ni(SNNS) complexes are diamagnetic and square-planar. The Zn(SNNS) complexes are assigned with polymeric structures with mercapto sulphur-bridging. The Cd(SNNS) complexes presumably have polymeric structures.     

Structural studies on cadmium(II), cobalt(II), copper(II), nickel(II) and zinc(II) complexes of 1-malonyl-bis(4-phenylthiosemicarbazide)

Summary Several new complexes of the title ligand (H₂MPTS) with Co^II, Ni^II, Cu^II, and Cd^II have been prepared. Structural assignments of the complexes have been made based on elemental analysis, molar conductivity, magnetic moment and spectral (i.r.,¹H n.m.r., reflectance) studies. The compounds are non-conductors in dimethylsulphoxide. The neutral molecule is coordinated to the metal(II) sulphate as a bidentate ligandvia the two carbonyl groups. The ligand reacts with the metal(II) chlorides with the liberation of two hydrogen ions, behaving as a bianionic quadridentate (NONO) donor. Enolization is confirmed by the pH-titration of H₂ MPTS and its metal(II) complexes against NaOH. A distorted octahedral structure is proposed for the Cu^II complex, while a square planar structure is suggested for both Co^II and Ni^II complexes. The stoichiometry of the complexes formed in EtOH and buffer solutions, their apparent formation constants and the ranges for obedience to Beer's law are reported for Co^II, Ni^II and Cu^II ions. The ligand pK values are calculated. The antimicrobial activity of H₂ MPTS and its Co^II, Ni^II, Cu^II and Mn^II complexes is demonstrated.     

Synthesis and thermodynamic properties of novel tripod ligands and their cobalt(II), nickel(II), copper(II) and zinc(II) complexes

Three novel compounds, based on the 1,3,5-benzene core with C₃-symmetry, have been prepared and characterized by elemental analysis, i.r. and ¹H-n.m.r. Thermodynamic properties of the ligands and their Co^II, Ni^II, Cu^II, and Zn^II metal complexes have been investigated and the corresponding stability constants obtained at 25.0 ± 0.1 °C and with I = 0.1 mol dm^–3 in KNO₃ by potentiometric titration. A linear free energy relationship exists between the stability constants of complexes and the protonation constants of ligands in the ternary system of the Cu^II-5-substituted phenanthroline-tripod ligand complexes.     

Rhodanine complexes of zinc(II), cadmium(II), mercury(II) and mercury(I)

The following rhodanine (HRd) complexes of zinc(II), cadmium(II), mercury(II) and mercury(I) have been prepared and studied by i.r. spectra: M(Rd)₂(NH₃)₂ (MZn, Cd) with a 4N,2S-six-coordination; Zn₃(Rd)₄(CH₃COO)(OH), Cd₂(Rd)₃(HRd)₃(CH₃COO)(H₂O) in which the acetato anion is bicoordinated; Hg(Rd)₂, Hg₂(HRd)₃(BF₄)₂·0.5(HAc or EtOH), Hg(HRd)(CF₃COO)₂·H₂O in which both the ligands HRd and Rd⁻ are S,N-bonded to the metal; Hg(HRd)₂Cl₂, Hg(HRd)₄(ClO₄)₂ in which the ligand HRd is S-bonded; Hg₃(Rd)₃ · NH₃ with S,N-bonded Rd⁻ ligand.     

Potentiometric determination of stability constants of cyanoacetato complexes of cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II) and lead(II)

Stability constants of cyanoacetato complexes of cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II) and lead(II) were determined potentiometrically at 25.0 +/- 0.1 degrees and ionic strength 2M (sodium perchlorate). The stability constants were evaluated by a weighted least-squares method.     

Cobalt(II), copper(II), nickel(II) and zinc(II) complexes of two novel Schiff base ligands and their antimicrobial activity

Two new, Schiff base ligands containing cyclobutane and thiazole rings, 4-(1-methyl-1-mesitylcyclobutane-3-yl)-2-(2,4-dihydroxybenzylidenehydrazino)thiazole (L¹H) and 4-(1-methyl-1-mesitycyclobutane-3-yl)-2-(2-hydroxy-3-methoxybenzylidenehydrazino)thiazole (L²H) and their mononuclear complexes with a 1:2 metal-ligand ratio have been prepared with acetate salts of Co^II, Cu^II, Ni^II and Zn^II in EtOH. The structures of the ligands and their complexes have been established by microanalyses, i.r., u.v.–vis., ¹³C- and ¹H-n.m.r. spectra, and by magnetic susceptibility measurements. The complexes are mononuclear. Thermal properties of the ligands and complexes have been studied by t.g.a. and d.s.c. techniques. Antimicrobial activities of the ligands and their complexes have been tested against eight different microorganisms. Some of the complexes and L¹H were found to be active against some of the microorganisms studied.     

Thermal decomposition of mixed ligand complexes of manganese(II), nickel(II), copper(II), zinc(II) and cadmium(II) containing triethanolamine and oxalate

The kinetics of thermal decomposition of mixed ligand complexes of Mn(II), Ni(II), Cu(II), Zn(II) and Cd(II) containing triethanolamine and oxalate have been studied using thermogravimetry (TG) and differential scanning calorimetry (DSC). The decomposition reaction in which the complexes lose one molecule of triethanolamine was found to be first order and the activation energy and pre-exponential factors were calculated using established techniques. The values of E_a obtained for these reactions using a modified form of the Horowitz and Metzger equation were 27.75, 20.54, 18.33, 25.32 and 23.25 kcal mole^?1, respectively. Infrared spectral data of these complexes and the intermediates gave additional information about the coordinating nature of the ligands in these complexes.     

Complexes of dicamba with cadmium(II), copper(II), mercury(II), lead(II) and zinc(II)

New solid complexes of a herbicide known as dicamba (3,6-dichloro-2-methoxybenzoic acid) with Pb(II), Cd(II), Cu(II) and Hg(II) of the general formula M(dicamba)₂·xH₂O (M=metal, x=0-2) and Zn₂(OH)(dicamba)₃·2H₂O have been prepared and studied. The complexes have different crystal structures. The carboxylate groups in the lead, cadmium and copper complexes are bidentate, chelating, symmetrical, in Hg(dicamba)₂·2H₂O - unidentate, and in the zinc salt - bidentate, bridging, symmetrical. The anhydrous compounds decompose in three stages, except for the lead salt whose decomposition proceeds in four stages. The main gaseous decomposition products are CO₂, CH₃OH, HCl and H₂O. Trace amounts of compounds containing an aromatic ring were also detected. The final solid decomposition products are oxychlorides of metals and CuO. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mechanically activated solid-phase synthesis of copper(II), zinc(II), and cadmium(II) diethyldithiocarbamates

The mechanically activated solid-phase reaction of copper, zinc, and cadmium chlorides with sodium diethyldithiocarbamate is studied. The course of the process and the extent of reaction are studied as affected by the parameters of the mechanical activation, subsequent heat treatment of the activated mixtures, and the nature of the reagents. Vacuum sublimation isolated zinc, copper, and cadmium diethyldithiocarbamates from mechanically activated mixtures. The extent of reaction reaches 97–99%.