Complexes of divalent oxovanadium,manganese, iron,cobalt, nickel and copper with the ligand derived from the reaction of 2-aminopyridine and acetylacetone

Summary 2-Aminopyridine reacts with acetylacetone in the presence of VO^II, Mn^II, Fe^II, Co^II, Ni^II, and Cu^II metal salts to give complexes of the type [VO(Ap₂ac)₂X]X and [M(Ap₂ac)₂X₂] where (Ap₂ac) is the ligand formedin situ. The complexes are characterised as distorted octahedral by analyses, conductance, molecular weight, magnetic, electronic and i.r. spectral studies. The i.r. studies reveal that two molecules of aminopyridine are joined by a molecule of acetylacetone through a three carbon atom bridge and that the ligand coordinates through the azomethine and imino nitrogen atoms, whereas pyridine does not take part in coordination. The electronic spectra have been interpreted and tentative assignments are made. In the far i.r. spectra, various metal ligand vibrations are observed and discussed. Attempts to carry out electrophilic substitutions in the complexes failed.     

Darstellung und Charakterisierung einige Thiocyanat- und Selenocyanat-Komplexe von Übergangsmetallen

Some 6:1 thiocyanate complexes of Fe^III, Mo^III, Ru^III, Os^III, Ir^III and some 6:1 or 4:1 selenocyanate complexes of Fe^II, Fe^III, Mo^III, Rh^III, Pd^II, Pt^II, and Au^III have been prepared as salts of large organic cations. The compounds are characterized by their infra-red spectra and by conductance measurements. In particular the linkage property of the thiocyanate and selenocyanate ligand is discussed together with the consequences it has on the AHRLAND -CHATT -DAVIES -PEARSON classification of the central ions.     

Derivatives of the 21-tungsto-9-antimonate heteropolyanion. Part 2. Addition of transition metal cations

Ammonium salts of five new heteropolytungstates, [NaSb₉W₂₁O₈₆M₃]^12,9− (M=Mn^II, Fe^III, Co^II, Ni^II, Cu^II) have been prepared and characterized by elemental analysis, visible and i.r. spectroscopy, magnetic susceptibility measurements, and cyclic voltammetry. Evidence for ligand substitution at the M cation centres is presented, and possible binding sites for M on the polyanion surface are discussed.     

Metal chelates of thiazole-2-ylthiourea

Summary The formation constants of 1-phenyl-3-thiazole-2-ylthiourea complexes with some bivalent metal ions (Cu^II, Ni^II, Zn^II and Mn^II) have been determined in 75% EtOH–H₂O. Complexes of Cu^II, Ni^II, Zn^II, Hg^II and Pd^II have been isolated and characterized by conductance, i.r., electronic spectra and magnetic measurements. The ligand forms ML complexes with Cu^II and Hg^II and ML₂ with Ni^II, Zn^II and Pd^II, where L is the uninegatively charged bidentate ligand and binds through the ring nitrogen and thiocarbonyl sulphur atoms.     

The vibrational analysis of some oxamide complexes

Summary The vibrational spectra of the oxamide and deuteriooxamide complexes with Ni^II, Pd^II, Cu^II, Zn^II and Co^III are presented. The vibrational analysis is given for a planarD _2h structure for the Ni^II, Cu^II and Pd^II compounds; the Zn^II and Co^III complexes have a tetrahedral and octahedral structure respectively.Presented in part at the XIX I.C.C.C. Prague 1978.     

Spectroscopic characterization of some metal complexes derived from 4-acetylpyridine nicotinoylhydrazone

Coordination compounds of Mn^II, Cu^II, Fe^III and Zn^II ions with 4-acetylpyridine nicotinoylhydrazone (4-APNH) were synthesized and characterized by elemental analyses, molar conductivity, magnetic moments, i.r., u.v./vis., m.s., ¹H-n.m.r. and thermal analyses. I.r. spectra show that the ligand can act either in the enol form as monovalent bidentate or in the keto form as neutral bidentate depending on the metal salt used. Octahedral structures are proposed for Fe complex and square – planar for the Cu complex, while tetrahedral structures were suggested for Zn and Mn complexes on the basis of magnetic and spectral evidences. Semi-empirical calculations ZINDO/1 have been used to study the molecular geometry and the harmonic vibrational spectra with the purpose to assist the experimental assignment of the complexes. In memory of the late Professor Dr. Abdel Hamid M. Shallaby 2/5/2006     

Preparation and characterization of divalent metal ion complexes ofN-2-picolyl-N-phenylthiourea

Summary New complexes ofN-2-picolyl-N -phenylthiourea (HPPT) have been prepared employing a number of different divalent metal ion salts. The resultant Co^II, Ni^II, and Cu^II complexes, which generally involve coordination of HPPT, except for the Cu^II halides which have a deprotonated ligand, have been characterized by partial elemental analysis, molar conductivity and spectral (i.r., u.v.-vis., and e.s.r.) studies. HPPT is an NN bidentate ligand while the deprotonated form serves as an NNS bridging tridentate ligand. The complexes undergo partial or total decomposition in the solvents in which they are soluble. The compounds [Cu(HPPT)₂X₂] have resolved g features in their powder spectra indicating that magnetic dilution has occurred.On leave from Mansoura University, Mansoura, Egypt.     

New complexes of iron(III), cobalt(II), nickel(II) and copper(II) with Schiff bases derived from 2-aminocyclopent-1-ene-1-dithiocarboxylic acid

Summary Fe^III, Co^II, Ni^II and Cu^II, complexes of a new Schiff base ligand, prepared by condensing 2-aminocyclopent-1-ene-1-dithiocarboxylic acid with benzaldehyde (ACB), and also Cu^II and Ni^II complexes of a second Schiff base ligand prepared by condensing 2-aminocyclopent-1-ene-1-dithiocarboxylic acid with salicylaldehyde (ACS), have been prepared and characterized by elemental analyses, conductivity measurements, magnetic and spectral (electronic, i.r. and e.p.r.) studies. The i.r. spectra suggest that both ACB and ACS are acting as bidentate ligands, coordinating through one of the sulphur atoms and through the azomethine nitrogen atom. The magnetic moment of the Fe^III complex indicates spin crossover behaviour. Square planar structures have been assigned to the Cu^II and Ni^II complexes and a tetrahedral structure to the Co^II complex. The e.p.r. spectra of the Cu^II complexes suggest a square planar environment with rhombic distortion around the Cu^II ion.     

Preparation and characterization of some transition metal complexes of benzoic acid hydrazones of 2-aminonicotinaldehyde

Summary Cu^II, Ni^II, Co^II, Zn^II and Pd^II complexes of tridentate Schiff base ligands derived from the condensation of benzoic acid hydrazides with 2-aminonicotinaldehyde have been prepared and characterized. For M=Cu, Ni, Co and Zn the complexes were formulated as [M(ligand)(H₂O)X] (X=Cl, Br), with a distorted octahedral geometry and tridentate Schiff base ligands. The Pd complexes were formulated as Pd(ligand)Cl₂, with square planar geometries and bidentate Schiff base ligands. The e.s.r. spectra of the Cu^II complexes are discussed.     

Fluoroazoles. III. Synthesis and 1H and 1–9F nmr spectra of 3-, 4-, and 5-fluoro-1-methylpyrazole

The three monofluoro derivatives of N-methylpyrazole have been synthesized. 3-Fluoro-1-methylpyrazole and 4-fIuoro-1-methylpyrazole were prepared from the appropriate amines by diazotization and photochemical irradiation of the diazonium salts in tetrafluoroboric acid. 5-Fluoro-1-methylpyrazole was obtained from 1-acetyl-3-fluoropyrazole and methyl fluorosulfonate, and also by direct methylation of 3(5) fluoropyrazole with dimethyl sulfate. The ^1–9F chemical shifts of these N-methylated fluoroazoles cover a great range (ca. 50 ppm) and show a good correlation with the chemical shifts of H₃, H₄, and H₅ protons of 1-methylpyrazole. An unexpected long-range coupling ⁵J (F-CH₃) is observed in 3-fluoro-1-methylpyrazole.     

Synthesis,characterization and antimicrobial activity of the Schiff bases derived from 2,4-disubstituted thiazoles and 3-methoxysalicylaldehyde,and their cobalt(II), copper(II), nickel(II) and zinc(II) complexes

Two new Schiff base ligands containing 2,4–disubstituted thiazoles and cyclobutane rings, 4-(1-methyl-1-phenylcyclobutane-3-yl)-2-(2-hydroxy-3-methoxybenzylidenehydrazino)thiazole (L¹H), 4-(1-methyl-1-p-xylylcyclobutane-3-yl)-2-(2-hydroxy-3-methoxybenzylidenehydrazino)thiazole (L²H) and their mononuclear complexes with a 1:2 metal–ligand ratio have been prepared from acetate salts of Co^II, Cu^II, Ni^II and Zn^II in EtOH. The authenticity of the ligands and their complexes have been established by microanalyses, i.r., ¹³C- and ¹H-n.m.r. spectra, and by magnetic susceptibility and conductivity 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 six different microorganisms; three are yeast and three are bacteria. One of the ligands and many of the complexes were found to be active against some of the microorganisms studied.     

Effect of substitution and the counterion on the structural and spectroscopic properties of CuII complexes of methylated pyrazoles

The coordination chemistry of pyrazole and three of its methyl derivatives with the chloride and nitrate salts of copper(II) under strictly controlled reaction conditions is systematically explored to gain a better understanding of the effect of counterion coordination strength and ligand identity on the structure and electronic absorption spectra of their resulting complexes. Despite the initial 2 : 1 ligand to metal ratio in water, copper(II) nitrate forms exclusively 4 : 1 ligand to metal complexes while copper(II) chloride forms a 4 : 1 ligand to metal complex only with pyrazole, with the methyl derivatives forming 2 : 1 ligand to metal complexes, as determined by single-crystal X-ray diffraction (XRD). This is attributed to a combination of ligand sterics and stronger coordination of chloride relative to nitrate. Electronic absorption spectroscopy in both water and methanol reveals a surprisingly strong effect of the pyrazole methyl position on the Cu^II d–d transition, with 4-methylpyrazole producing a higher energy d–d transition relative to the other ligands studied. In addition, the number of methyl groups plays a determining role in the energy of the pz π→Cu^II d_xy LMCT band, lowering the transition energy as more methyl groups are added.     

Synthesis,characterization and biological evaluation of manganese(II), cobalt(II), nickel(II), copper(II), and cadmium(II) complexes with monobasic (NO) and neutral (NN) Schiff bases

New complexes of Mn^II, Co^II, Ni^II, Cu^II, and Cd^II with bis(acetophenone) ethylenediamine and 5-chlorosalicylideneaniline or 5-bromosalicylideneaniline have been prepared and characterized on the basis of elemental analyses, thermogravimetric analyses, magnetic measurements, electronic and i.r. spectra. The antimicrobial activities of the complexes, ligands, control (dimethyl formamide) and metal salts were tested against Salmonella typhi (bacteria), Saccharomyces cerevisae (yeast), and two fungal species Lasiodiplodia theobromae and Fusarium oxysporum. The results are discussed.     

Synthesis and antibacterial activity of metal complexes of cefazolin

Cefazolin (Hcefaz) interacts with transition metal(II) ions to give [M(cefaz)Cl] complexes (M = Mn^II, Co^II, Ni^II, Cu^II, Zn^II, Pd^II) and [Ag₂(cefaz)₂Cl₂] which were characterized by physicochemical and spectroscopic methods. Their i.r. and the ¹H-n.m.r. spectra suggest that cefazolin behaves as a monoanionic tetradentate ligand. The complexes have been screened for antibacterial activity and the results are compared with the activity of cefazolin.     

Synthesis and Characterization of Two New Schiff Base Ligands and their Complexes with Cobalt(II), Nickel(II) and Copper(II)

Two Schiff base ligands, 2-{E-[(5-phenyl-6H-1,3,4-thiadiazin-2yl)imino]methyne}-1-naphthol (L¹H) and 5-nitro-2-{[(5-phenyl-6H-1,3,4-thiadiazin-2-yl)imino]methyne}phenol (L²H) have been prepared from 5-phenyl-6H-1,3,4-thiadiazin-2-amine (A), 2-hydroxynaphthaldehyde (1) and 2-hydroxy-5-nitrobenzaldehyde (2) Mononuclear Co(II), Ni^II and Cu^II complexes of the ligands have been prepared by using Co^II, Ni^II and Cu^II salts with a 1:2 metal:ligand ratio. It was determined that the bidentate behavior of the ligands is accomplished via the phenolic oxygen and the azomethine nitrogen atoms. The structures of the ligands and their complexes were identified by using elemental analyses, i.r., ¹H-n.m.r. spectra, electronic spectra, magnetic susceptibility measurements and thermogravimetric analyses (t.g.a.).     

2-Aminoacetophenone-2-thenoylhydrazone complexes of bivalent 3d metal ions

Summary 2-Aminoacetophenone-2-thenoylhydrazone, Haath, C₄H₃SC(O)NHN=C(Me)C₆H₄NH₂-o, forms complexes with metal(II) salts of empirical compositions [VO(Haath)₂SO₄], [M(Haath)₂Cl₂] [M=Co^II, Ni^II, Cu^II or Zn^II] and [M(aath)₂] [M=V^IVO, Co^II, Ni^II, Cu^II or Zn^II] which have been characterized by elemental analyses, molar conductance, magnetic susceptibility, electronic, e.s.r., i.r. and n.m.r. (¹H and¹³C) spectral studies. X-ray and electron diffraction patterns have been obtained in order to elucidate the structure of the Cu^II complexes. Photoacoustic spectra of powder Ni^II complexes have been recorded and interpreted in the light of u.v./vis. spectra.     

Coordination compounds of hydrazine derivatives with transition metals,Part 17. Nickel (II) and cobalt(II) chelates with pyridine-2-aldehyde semi- and thiosemicarbazone

Summary The chelation abilities of both pyridine-2-aldehyde semicarbazone (Pysc) and thiosemicarbazone (Pytsc) towards Ni^II and Co^II salts have been investigated. A series of pentacoordinate monoligand chelates: Ni(Pysc)X₂, Ni(Pytsc)X₂ and Co(Pysc)X₂ and octahedral bis ligand chelates Ni(Pysc)₂X · NO₃ Ni(Pytsc)₂X₂ and Co(Pysc)₂X₂ have been isolated and identified. In these chelates, both Pysc and Pytsc act as neutral tridentate ligands. The deprotonated form of Pyts, which arises through enolization, is identified in N^II chelates and is of the type Ni(PytscH)₂ and Ni(PytscH)X. Spectral and magnetic measurements are presented and attention is drawn to the effect of temperature on the solution spectra of some of the chelates.     

Synthesis and properties of 7-formyl-8-hydroxyquinoline and its transition metal complexes

Summary Co^II, Ni^II, Cu^II, Cd^II and Hg^II complexes of 7-formyl-8-hydroxyquinoline (HFHQ) have been prepared, and characterized by elemental analysis, molar conductivities, electronic and i.r. spectra, and magnetic measurements. It was found that the ligand acts as a neutral monodentate or a monobasic bidentate donor. The Co^II, Ni^II and Cu^II complexes possess, respectively, tetrahedral, octahedral and square-planar structures based on their magnetic and electronic spectral data. The electrical conductivities of HFHQ and its metal complexes were measured at different temperatures and their activation energies were calculated. The values obtained for the Co^II, Ni^II, Cd^II and Hg^II complexes agree fairly well with those reported for semiconductors. The ligand was tested as a corrosion inhibitor for aluminium; the limiting concentration of HFHQ to give maximum efficiency (99.2%) is 10^–3 mole dm^–3 at 22°C. The metal-ligand ratios and apparent formation constants for the species generated in ethanol solution were determined spectrophotometrically.     

Transition metal complexes derived from ethyl-α-(N-phenylthiocarbamyl)cyanoacetate

Summary Complexes of Co^II, Ni^II, Cu^II, Zn^II, Pd^II, Cd^II, Hg^II and Cu^I with ethyl--(N-phenylthiocarbamyl)cyanoacetate (HETCA) have been synthesized and characterized. The i.r. spectra show that HETCA behaves as a mononegative bidentate ligand, in the thiol tautomeric form. HETCA reduces CuCl₂ to give a diamagnetic Cu^I complex. A tetrahedral structure is proposed for the Co^II complex, while a square-planar structure is proposed for the Ni^II, Cu^II, and Pd^II complexes.     

Spectroscopic,thermal and electrochemical characterization of synthesized divalent transition metal complexes with cysteine and 4-substituted thiosemicarbazides

Mixed ligand complexes of Co^II, Ni^II and Cu^II with cysteine and 4-substituted thiosemicarbazides (l ¹–l ³) have been synthesized. The elemental analyses, molar conductance, spectra [electronic, i.r., ¹H-n.m.r., mass] and thermal studies were used to characterize the isolated complexes. Cyclic voltammetry was used to study the electrochemical behaviour of the Ni^II complexes. The i.r. and ¹H-n.m.r. showed that cysteine is deprotonated in the complex and acts as a binegative ligand coordinating through thiol sulphur and COOH groups. Also, thiosemicarbazides act as a bidentate ligand, coordination via NH₂ and (C=S) groups. Square-planar geometry has been proposed for Co^II, Ni^II and Cu^II ternary complexes.