Transition metal(II) complexes of 1-(α-hydroxynaphthyl)-2-(3′-methyl-5′-mercapto-1′,2′,4′-triazole)-2-aza-ethane

Summary Binuclear metal complexes of the type [M(HMTE)-(H₂O)₂]₂, where HMTE=1-(-hydroxynaphthyl)-2-(3-methyl-5-mercapto-1,2,4-triazolc)2-aza-ethane and M-Cu^II, Co^II, Ni^II and Mn^II have been prepared and characterized. An octahedral geometry around the metals is proposed. The complexes have been screened as possible fungicides.     

N2S2 macrocyclic ligands. Synthesis and characterization of novel transition metal complexes of the type [LM(Si2Me6NH)2]2+ and [L′M(Si2Me6NH)2]2+

Summary Novel N₂S₂ macrocyclic ligands, L and L [SS-diethyl(1,3-diaminopropane) dithiocarbamate], [SS-cyclohexyl spiro-(1,3-diaminopropane) dithiocarbamate] and their complexes with Mn^II, Fe^II, Co^II, Ni^II and Cu^II have been characterized by elemental analyses, conductivity measurements, i.r., u.v.-vis. and n.m.r. spectra. The divalent transition metal complexes appear to be square planar and achieve octahedral geometry when treated with bis(trimethylsilyl)-amine to yield new heterobimetallic complexes.     

Synthesis and characterization of new 13 and 14-membered macrocycles and their transition metal complexes

Two new macrocyclic ligands 1,4,7,9,12-pentaaza-10,11-dioxo-8,9,12,13-bis-(1-oxo-3-thio-2-hydropyrimidine)-trideca-7,13-diene, (L¹) and 1,4,7,9,12-pentaaza-10,12-dioxo-8,9,13,14-bis-(1-oxo-3-thio-2-hydropyrimidine)-tetradeca-7,14-diene, (L²) and their complexes with Cr^III, Mn^II, Fe^III, Co^II, Ni^II, Cu^II and Zn^II have been synthesized, and characterized by elemental analysis, i.r., ¹H-n.m.r., e.p.r., u.v.–vis. spectroscopy, magnetic susceptibility and conductance measurements. The conductivity measurements suggest that the complexes of divalent metal ions are 1:1 electrolytes whereas the trivalent metal ions are non-electrolytes. On the basis of electronic spectra and magnetic moment measurements the Cr^III and Fe^III complexes are octahedral, while the divalent metal complexes are tetrahedral except for the Ni^II and Cu^II complexes which are proposed to have square planar geometry. All the ligands and their complexes have been screened against gram-positive bacteria Staphylococcus aureus and gram-negative bacteria E. coli. The results show that they inhibit the growth of bacteria.     

Nickel(II) and copper(II) – l-cysteine,l-methionine,l-tryptophan-nucleotide ternary complexes

Four new ternary complexes of Cu^II with l-methionine and the nucleotides 5AMP (adenosine 5-phosphate), 5GMP (guanosine 5-phosphate) and 5IMP (inosine 5-phosphate), and with l-tryptophan and 5AMP, were synthesized and characterized by elemental analysis and i.r. spectroscopy. One ternary complex of N^II with l-cysteine and 5IMP was also prepared and characterized. The study of the three ternary compounds of Cu^II, of general formulae Cu-5NMP-l-methionine, indicates coordination of the phosphate group and of N(7) of the purinic ring. l-Methionine is bound by the carboxylic and amino groups. The ternary complex obtained from a mixture of Cu-5AMP and l-tryptophan is a dimer in which the nucleotide bridges the two copper atoms. In the complex of Ni-5IMP and l-cysteine, the nucleotide seems to bind the metal through the N(7) of the heterocyclic ring, and the l-cysteine is coordinated as a bidentate chelate by the carboxyl and thiol groups. E.s.r. spectra of the copper complexes are in good agreement with the low symmetry structure proposed. The one-electron reduction potentials E_c(Fc⁺/Fc) (V) of Cu^II to Cu^I were established for the four copper complexes from cyclic voltammetry studies. The one-electron oxidation potential E_a(Fc⁺/Fc⁺) (V) of Ni^II to Ni^III was also measured for the nickel complex.     

Homo- and heterodinuclear 2,2′-bipyrimidine-bridged complexes

[M(hfacac)₂(bpym)] complexes, where M = Co^II, Ni^II or Zn^II, hfacac = hexafluoroacetylacetonate and bpym = 2,2bipyrimidine; and [Cl₂M(bpym)M(hfacac)₂] complexes, where M = Co^II, Ni^II Mn^II or ZnII M = Ni^II; M = NiII or Zn^II and M = Zn^II; M = Ni^II and M = Co^II have been prepared and characterized by chemical analysis, conductance measurements, IR and electronic spectroscopies and magnetic susceptibility measurements (4.2–292K range). The dinuclear NiII–Ni^II, Co^II–Ni^II and Mn^II–Ni^II complexes are antiferromagnetic, with an intramolecular exchange parameter, J, of –2.3–8.9cm–1. Co^II and Mn^II are in a high spin state. The low temperature effect observed in monomers and in Ni^II–Zn^II dimers is considered a consequence of either an intermolecular antiferromagnetic interaction or the zero-field splitting in NiII.     

Cobalt(II) and nickel(II) chloride and bromide complexes of 2-(2′-methyl-8′-quinolyl)benzoxazole and 2-(2′ or 4′-methyl 8′-quinolyl)benzimidazole

Summary Cobalt(II) and nickel(II) halide complexes of the ligands 2-(2-methyl-8-quinolyl)benzoxazole (mqbo), 2-(2-methyl8quinolyl)benzimidazole (mqbi) and 2-(4-methyl-8-quinolyl)benzimidazole (mqbi) were synthesized and characterized by analytical, thermogravimetric, conductivity and magnetic data, and i.r. and electronic spectra.The ligands are bidentate N-donors yielding complexes where the coordination geometry depends on the metal ion and steric hindrance. All the cobalt complexes have formula [CoL₂X₂] and distorted tetrahedral geometry. Different types of nickel compounds were obtained: i) complexes of formula NiLX₂ · n H₂O (or EtOH) (L = mqbo or mqbi; n=0–1.5) which arepseudo-tetrahedral or five-coordinate and ii) complexes NiL₂X₂ · n H₂O (L = mqbi, n=3 or 4) where the metal is bound to four nitrogen atoms and the overall coordination geometry is tetragonal. The structural changes occurring after removal of water or alcohol from the complexes are also reported.     

Copper(II) chloride complexes of 2-(4′-Methyl-2′-pyridyl)-benzoxazole,their sulphur and nitrogen analogues and 2-(4′-Methyl-2′ {or8′} -quinolyl)benzoxazoles

Summary Copper(II) complexes CuLCl₂, where L=2-(4-methyl-2-pyridyl)benzimidazole(mpbi); 2-(4-methyl-2-pyridyl)benzothiazole(mpbt); 2-(4-methyl-2-pyridyl)benzoxazole (mpbo); 2-(4-methyl-2-quinolyl)benzoxazole (mqbo); 2-(4-methyl8-quinolyl)benzoxazole (mqbo), and Cu(mpbi)₂Cl₂(H₂O) have been synthesized and characterized by conductivity and magnetic measurements as well as by i.r., electronic and e.s.r. spectra. The ligands are bidentate donors through the pyridine and isoxazole nitrogen atoms. The CuLCl₂ complexes exhibit spectral properties consistent with CuN₂Cl₂ chromophores differing in the degree of tetrahedral distortion, which is found to parallel the steric hindrance near the donor sites. Cu(mpbi)₂ Cl₂(H₂O) is five-coordinate.     

Binuclear and mononuclear cobalt(II), nickel(II) and copper(II) complexes of 4,4′-bis(alkylaminoisonitrosoacetyl)diphenyl-methane derivatives

4,4-Bis(chloroacetyl)diphenylmethane has been prepared from ClCH₂COCl and Ph₂CH₂. 4,4-Methylenebis(phenylglyoxylohydroximoyl chloride has also been obtained. Four new substituted 4,4-bis(alkylaminoisonitrosoacetyl)diphenylmethanes (ligands) have been prepared from 4,4-methylenebis(phenylglyoxylohydroximoyl chloride) and the corresponding amines. The Ni^II, Cu^II and Co^II complexes of these ligands were prepared and their structures were identified using AAS, i.r., ¹H-n.m.r. spectral data, elemental analyses and magnetic susceptibility measurements.     

Synthesis and characterisation of some complexes of manganese(II) and iron(II) picrates with heterocyclic amines

Summary Complexes of manganese(II) and iron(II) picrates with various bidentate (L) and monodentate (L) heterocyclic bases have been synthesised; their compositions have been established as [ML₃]A₂ (1), [ML₂ · 2 H₂O]A₂ (2), [ML₆]A₂ (3) and [ML4 · 2 H₂O]A₂ (4), where M = Fe^II and Mn^II, L = 2,2-bipyridyl (bipy) and 1,10-phenanthroline (phen) in (1), A = picrate anion; M = Mn^II, L = bipy and phen in (2); M = Fe^II, L = pyridine (py), 4-picoline (4-pic) and 3-picoline (3-pic) in (3); M = Mn^II, L = py, 4-pic, quinoline (quin) and 2,6-lutidine (2,6-lut) in (4) and also M = Fe^II, L = quin and 2,6-lut.     

Complexes of 2-(2-hydroxyacetophenone)imino-5-(p-anisyl)-1,3,4-oxadiazole with some bivalent metals ions

Summary The metal complexes of the type [M(SB)₂(H₂O)₂] and [M(SB)₂][where M = Mn^II, Co^II, Ni^II or Cu^II, M = Zn^II Cd^II, Hg^II and Pb^II and SBH = 2-(2-hydroxyacetophenone)imino-5-(p-anisyl)-1,3,4-oxadiazole] have been prepared and characterised by elemental analyses, thermal analyses, magnetic measurements, electronic and infrared spectral studies. The complexes [M(SB)₂(H₂O)₂] possess octahedral structures, whereas complexes [M(SB)₂] are tetrahedral. The crystal field parameters of the Co^II and Ni^II complexes are also calculated.     

Preparation and electrochemical study of manganese(II) macrocycles containing terpyridine

The macrocycle, L, prepared by template condensation of bis-6,6-(-methylhydrazino)-4-phenyl-2,2:6,2-terpyridine with glyoxal, forms a stable crystalline Mn^II complex, [Mn(L)(H₂O)₂][PF₆]₂, which has been used as a starting material for electrochemical studies on a series of seven coordinate Mn^II complexes [Mn(L)X₂]²⁺ (X = pyridine, 4-cyanopyridine, 4-aminopyridine, 4-dimethylaminopyridine, pyrazine, imidazole 1-methylimidazole, 2-dimethylimidazole or Ph₃P). Cyclic voltammetry of the complexes in MeCN shows a reversible one electron reduction wave in the range –1.32 to –1.42 V versus the Ag/AgBF₄ reference electrode.     

Synthesis of new dinuclear dicopper(II) and dinickel(II) complexes. The kinetics of catechol oxidase and electrochemistry of a dicopper(II) complex

A new dinuclear ligand L, ethylene[OO-bis-salicylidene--diketone] bearing two symmetrical coordination sites was synthesized by the condensation of salicylaldehyde and acetylacetone, L, with 1,2-dibromoethane under reflux. The ligand L in a 1:1 ratio was treated with CuCl₂ and NiCl₂ to yield the complexes, tetrachloro bis[OO-bis- salicylidene--diketone copper(II)] and bis[OO-bis-salicylidene--diketone nickel(II)] chloride. The complexes were subsequently characterized by spectroscopic techniques, elemental analysis, i.r., ¹H-n.m.r., ¹³C-n.m.r., u.v.–vis., e.p.r. spectroscopy, and conductance measurements. The conductance measurements in DMF reveal that the Cu^II complex is covalent while the Ni^II complex is ionic and the spectral data support the Cu^II complex to be distorted octahedral whereas the Ni^II complex has square-planar geometry. The dioxygen binding was studied spectrophotometrically by the oxidation of tetrachloro bis[OO-bis-salicylidene--diketone copper(II)] with pyrocatechol in the presence of oxygen. The kinetic experiments were performed with the copper complex in DMF by monitoring the increase in absorbance over time at pH 8.0 in the presence of pyrocatechol at 25 °C. The kinetic parameters V_max and K_M were determined on the Michaelis–Menten Approach. Redox behavior of the dinuclear copper(II) complex was investigated by cyclic voltammetry in the presence of O₂ with the pyrocatechol (substrate) and also without the substrate. The large difference in potentials E⁰ is indicative of reversible oxygen binding of the complex and distinct catalytic activity.     

Preparation and electrochemical study of an iron(II) complex of a pentadentate planar macrocyclic ligand

The macrocycle L, prepared by template condensation of bis-6,6-(-methylhydrazino)-4-phenyl-2,2:6,2-terpyridine with glyoxal, forms a stable crystalline complex of Fe^II, [Fe(L)(H₂O)₂][PF₆]₂, which has been used as a starting material for electrochemical studies on a series of seven coordinate Fe^II complexes [Fe(L)X₂]²⁺ (X=pyridine, 4-cyanopyridine, 4-aminopyridine, 4-dimethylaminopyridine, thiophene, imidazole, 2-methylimidazole or 1,2-dimethylimidazole). Cyclic voltammetry of the aquo complex in MeCN shows three reversible one electron redox waves in the range –0.35–1.70V versus Ag/AgBF₄ reference electrode.     

Cobalt(II) and nickel(II) complexes of N(4′) substituted 3- and 4-acetylpyridine thiosemicarbazones

Co^II and Ni^II complexes of N(4)-methyl and N(4)-ethyl thiosemicarbazones derived from 3- and 4-acetylpyridine have been prepared and characterized by microanalyses, magnetic susceptibility and molar conductivity measurements and by their electronic, i.r. and n.m.r. (in the case of Ni^II complexes) spectra.     

Copper(II) chloride and bromide complexes of 2-(2′-Methyl-8′-quinolyl)benzoxazole and 2-(2′ or 4′-methyl-8′-quinolyl)benzimidazole

Summary Copper(II) complexes [CuLX₂], where L = 2-(2-methyl-8-quinolyl)benzoxazole, 2-(2-methyl-8-quinolyl)benzimidazole or 2-(4-methyl-8-quinolyl)-benzimidazole and X = Cl or Br, have been synthesized and characterized by conductivity and magnetic measurements, i.r., electronic and e.s.r. spectra.The ligands always behave as bidentateN-donors giving rise to monomeric compounds withpseudo-tetrahedral coordination geometry.     

Nitration,amination, and halogenation of Di-O-methylphloracetophenone

Chlorination of the title compound gave 5- and 3-chloro-2-hydroxy-4,6-dimethoxyacetophenone. The nitration of its acetate, followed successively by reduction, diazotization, and reaction with cuprous chloride, gave the 3-substituted series, 2-acetoxy-4,6-dimethoxy-3-nitroacetophenone, 3-amino-2-hydroxy-4,6-dimethoxyacetophenone, and 3-chloro-2-hydroxy-4,6-methoxyacetophenone, respectively. The orientation of substituents in the products was proved. The amino and chloro members of the isomeric 5-substituted series were availablevia 2-hydroxy-4,6-dimethoxy-5-phenylazoacetophenone, the product of the reaction of the title compound with benzenediazonium chloride.

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Nitrierung, Aminierung und Halogenierung von Di-O-methylphloracetophenon

Zusammenfassung Chlorierung der Titelverbindung gab 5- und 3-Chlor-2-hydroxy-4,6-dimethoxyacetophenon. Die Nitrierung des Acetats, gefolgt von Reduktion, Diazotierung und Reaktion mit CuCl ergab die 3-substituierte Reihe: 2-Acetoxy-4,6-dimethoxy-3-nitroacetophenon, 3-Amino-2-hydroxy-4,6-dimethoxyacetophenon und 3-Chlor-2-hydroxy-4,6-dimethoxyacetophenon. Die Orientierung der Substituenten wird diskutiert. Die Amino- und Chlorderivate der isomeren 5-substituierten Reihe sind über 2-Hydroxy-4,6-dimethoxy-5-phenylacetophenon zugängig, dem Produkt der Reaktion der Titelverbindung mit Phenyldiazoniumchlorid.

     

Vanadyl ion complexes with nucleotides

Summary Complexes of adenosine-5-triphosphate, adenosine-5-monophosphate, guanosine-5-monophosphate, inosine-5-monophosphate, cytidine-5-monophosphate and uridine-5-monophosphate with vanadyl ion, have been studied in the solid state by i.r. spectroscopy and magnetochemically. All complexes have normal magnetic moments, very close to the spin-only values. From the i.r. spectra it is suggested that the vanadyl ion is interacting with adenosine-5-triphosphate, through the N-1 of the purine ring, with adenosine-5-monophosphate, guanosine-5-monophosphate, inosine-5-monophosphate, through the N-7 of the purine ring, with cytidine-5-monophosphate through the N-3 of the pyrimidine ring, and most probably through the phosphate group with uridine-5-monophosphate. The complexes of vanadyl ion with the nucleotides are probably polymeric.     

Oxidation of cobalt(II) aminopolycarboxylate complexes by peroxomonophosphoric acid in acetate buffers. A kinetic study

Summary The kinetics of oxidation of the Co^II complexes [Co(edta)]^2– and [Co(hedta)]^– [H₄edta=ethylenediamine tetraacetic acid and H₃hedta=N-(2-hydroxyethyl)ethylenediamineN, N, N triacetic acid] by peroxomonophosphoric acid (PMPA) in acetate buffer were investigated spectrophotometrically. The reactions exhibit first order behaviour in each reactant and are markedly in hibited by H⁺. A plausible mechanism consistent with the observed results is proposed.     

Preparations and properties of vanadium(III) complexes of bidentate and terdentate nitrogen-donor ligands

Summary Vanadium(III) chloride reacts with 1,10-phenanthroline and 2,2-bipyridyl, and with substituted derivatives of each ligand (B), in ethanol or in acetonitrile as solvent (L), to yield two different series of complexes. These are (a) the neutral species VCl₃BL, where B = 1,10-phenanthroline, 5-chloro-1,10-phenanthroline, 5-methyl-1,10-phenanthroline, 4,7-dimethyl-1,10-phenanthroline, 2,2-bipyridyl, 4,4-dimethyl-2,2-bipyridyl, L = ethanol. The complexes in which B = 1,10-phenanthroline or 2,2-bipyridyl were also obtained with L = acetonitrile, (b) [VCl₂B₂]⁺[VCl₄B]^– where B is the same series of ligands listed above. Vanadium(III) chloride yields VCl₃ (terpy) with 2,2,2 -terpyridyl. All the complexes have been characterised by elemental analyses, conductance measurements, electronic- and i.r. spectral measurements, and by their temperature-range (297–77 K) magnetic moments; ring substituents have little influence on any chemical or physical properties of these complexes.     

New bis-macrocyclic complexes with transition metal ions

Template condensation of benzidine, formaldehyde, ethylenediamine or 1,3-diaminopropane, metal salt and 1-phenyl-1,3-butanedione or 2,3-butanedione in a 1:4:2:2 molar ratio results in the formation of two new series of binuclear pentaaza macrocyclic complexes: dichloro[1,1-phenylbis(7-methyl-9-phenyl-1,3,6,10,13-pentaazacyclotetradeca-6,9-diene) metal(II)], [M₂LCl₄] (M = Co^II, Cu^II, Fe^III and Zn^II) and dichloro[1,1-phenylbis(8,9-dimethyl-1,3,7,10,14-pentaazacyclopentadeca-7,9-diene) metal(II)], [M₂LCl₄] (M = Ni^II, Co^II, Cu^II and Cd^II). Both series were characterized by i.r., ¹H-n.m.r., u.v.–vis. spectral studies, conductivity and magnetic susceptibility measurements.