Chelated complexes of cadmium(II), cobalt(II), copper(II), mercury(II), nickel(II), uranyl(II) and zinc(II) with benzil bis(4-phenylthiosemicarbazone)

Summary Complexes of Co^II, Ni^II, Cu^II, Zn^II, Cd^II, Hg^II and UO ₂ ^II with benzil bis(4-phenylthiosemicarbazone), H₂BPT, have been synthesized and their structures assigned based on elemental analysis, molar conductivity, magnetic susceptibility and spectroscopic measurements. The i.r. spectra suggest that the ligand behaves as a binegative quadridentate (NSSN) (Co^II, Cu^II, Hg^II and UO ₂ ^II complexes) or as a binegative quadridentate-neutral bidentate chelating agent (Ni^II, Zn^II and Cd^II complexes). Octahedral structures for the Co^II and Ni^II complexes and square-planar structure for the Cu^II complex are suggested on the basis of magnetic and spectral evidence. The crystal field parameters (Dq, B and _B) for the Co^II complex are calculated and agree fairly well with the values reported for known octahedral complexes. The ligand can be used for the microdetermination of Ni^II ions of concentration in the 0.4–6×10^–4 mol l^–1 range and the apparent formation constant for the species generated in solution has also been calculated.     

Synthesis,spectral and antimicrobial activity studies of o-aminoacetophenone o-hydroxybenzoylhydrazone complexes

Coordination compounds of Mn^II, Co^II, Ni^II, Cu^II, Zn^II, Cd^II and Hg^II ions with o-aminoacetophenone o-hydroxybenzoylhydrazone (AAOHBH) were synthesized and characterized by elemental analyses, molar conductivity, magnetic moments (at ca. 25°C) and spectral (i.r., u.v., n.m.r. and m.s.) studies. The i.r. spectra show that the ligand acts in a monovalent bidentate, neutral bidentate and/or neutral tridentate fashion, depending on the metal salt used and the reaction medium. Tetrahedral structures are proposed for both Co^II and Ni^II complexes and square planar for Cu^II complexes on the basis of magnetic and spectral evidence. The complex formation in solution was investigated potentiometrically and spectrophotometrically. Spectral studies in solution show that the ligand can be used for the microdetermination of Co^II ion within a metal concentration up to 46.3p.p.m. The electrical conductivity of AAOHBH and its metal complexes was determined. The tendency of AAOHBH to form complexes with Co^II, Ni^II, Cu^II, Cd^II and Hg^II ions in 50% aqueous-dioxane was studied by pH measurements.The antimicrobiol activity of AAOHBH and its complexes derived from Co^II, Ni^II and Cu^II illustrates that the Ni^II complex seems to be inert towards Escherichia coli and Bacillus subtilis. The antimicrobial activity of the Cu^II complex was higher against E. coli and lower against B. subtilis than the corresponding organic ligand. The Co^II complex has the same activity as the organic ligand against E. coli.     

Ligational,thermal, corrosion inhibition and antimicrobial properties of salicylidinebenzenesulphonylhydrazone

Summary Complexes of Cu^II, Co^II, Ni^II, Cd^II, Zn^II and Hg^II with salicylidinebenzenesulphonylhydrazone (HSBS) have been prepared and characterized by elemental analyses, molar conductivities, magnetic moments, spectral (visible, i.r., n.m.r.) and thermal (d.t.a., t.g., d.t.g.) measurements. The magnetic and spectral studies confirm that the Ni^II complex is square, whereas the Co^II complex is tetrahedral. The molar conductivities for the complexes lie in the non-electrolyte range. The corrosion inhibition of aluminium using HSBS was studied by chemical and electrochemical methods. Also, the antimicrobial activities of HSBS and its complexes have been investigated.     

Transition metal complexes derived from 2-hydroxyimino-3-(2′-hydrazonopyridyl)-butane

Summary The complexes of Mn^II, Co^II, Ni^II, Cu^II, Zn^II, Cd^II, Hg^II, Co^III and UO ₂ ²⁺ ions with 2-hydroxyimino-3-(2-hydrazonopyridyl)-butane (HL) have been synthesised and characterized by elemental analyses, molar conductivities, magnetic measurements and spectral (i.r., visible, n.m.r.) studies. I.r. spectra show that HL behaves as a neutral or mononegative ligand and binds in a bidentate and/or tridentate manner. Also, HL behaves as oxidizing agent towards Co^II forming diamagnetic Co^III complexes depending on the preparative conditions. Different stereochemistries are proposed for Mn^II, Co^III, Co^II, Ni^II and Cu^II on the basis of spectral and magnetic studies.     

Metal complexes of tetramethylethylenediaminetetraacetate

Summary A number of metal complexes of the ligand tetramethylethylenediaminetetraacetate [Edta(OMe)₄ = L] have been characterised. The complexes may be formulated MLCl₂ · xH₂O where M²⁺ = Mn^II, Fe^II, Co^II, Ni^II, Cu^II, Cd^II, Hg^II and Sn^II. I.r., conductivity, magnetic susceptibility and electronic spectral data 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.     

Fluorenone hydrazine-S-benzyldithiocarbazate transition metal complexes

Summary New Cu^II, Co^II, Ni^II, Cd^II, Zn^II, Hg^II, Pd^II and UO ₂ ^II complexes of the Schiff base ligand (FBz) formed by condensation of fluorenone withS-benzyldithiocarbazate have been prepared and characterized by elemental analysis, magnetic and spectroscopic measurements. The Cu(FBz)₂(Cl)₂ complex is paramagnetic. The Ni(FBz-H)₂ complex is diamagnetic, four-coordinate and square planar. The Co^II ion is oxidized in the presence of the Schiff base with the concomitant formation of Co^III complex of empirical formulae Co(FBz)Cl₃OH₂. The ligand was tested as a corrosion inhibitor for copper. Inhibition efficiency was calculated and the limiting concentration of FBz to give maximum efficiency was 10^–3 mol dm^–3 at 25°C. The polarographic reduction of FBz was investigated in Britton-Robinson buffer solutions of pH 3–10. The polarograms at dme indicated that the depolarizer is reduced through two two-electron irreversible diffusion-controlled waves. The mechanistic pathway of the electrode reaction is commensurate with this result.     

Synthesis and spectral characterization of some investigated thiocarbohydrazone binuclear complexes with an illustrated EPR study for d<Superscript>1</Superscript> complexes

Some new complexes were synthesized using pyrol-2-carbaldhyde thiocarbohydrazone ligand and characterized using physicochemical techniques. The i.r. data reveal that, the ligand acts as a mononegative tetradentate in Ni^II and Cu^II binuclear complexes. Also, they coordinate as mononegative tridentates with Co^II, Cd^II and VO²⁺ ions but in the neutral state with Pt^IV ion in a mononuclear monomer structure for Co^II and Cd^II complexes, but binuclear dimer structure through bridged sulphate for the VO²⁺ complex. The magnetic moment beside the electronic spectral data proposed the complex geometries as a mixed stereochemistry for Ni^II, square-planar for Cu^II, square-pyramidal for VO²⁺ and octahedral for the other complexes. The thermal analysis supports the proposal of the presence or absence of water molecule in or outside the coordination sphere. The EPR spectra of Cu^II and VO²⁺ complexes were illustrated elaborately and some theoretical data were abstracted from EPR curves to support the proposed structures.     

Synthesis, Characterization and Antibacterial Activity of Some Transition Metal cis-3,7-dimethyl-2,6-octadiensemicarbazone Complexes

The synthesis and characterization of some transition metal cis-3,7-dimethyl-2,6-octadiensemicarbazone (CDOSC) complexes are reported. The ligand CDOSC yields: [ML₂ Cl₂] and [ML₂ Cl₂] Cl type complexes, where M = Cr^III, Mn^II, Fe^III, Co^II, Ni^II, Cu^II, Zn^II, Cd^II and Hg^II, L = CDOSC. Structures of the complexes were determined using elemental analysis, molar conductivity, magnetic measurements, i.r. and electronic, as well as n.m.r spectra. CDOSC acts as a bidentate ligand in all the complexes. All the newly synthesized metal complexes, as well as the ligand, were screened for their antibacterial activity. All the complexes exhibit strong inhibitory action against Gram (+) bacteria Staphylococcus aureus and Gram (−) bacteria Escherichia coli. The antibacterial activities of the complexes are stronger than those of the ligand CDOSC itself.     

Electrical conductivity,spectral and magnetic properties of some transition metal complexes derived from dimedone bis(4-phenylthiosemicarbazone)

Summary Co^II, Ni^II, Cu^II, Zn^II, Cd^II and U^VIO₂ complexes of 5, 5-dimethyl-1, 3-cyclohexanone bis(4-phenylthiosemicarbazone), H₂CPT, have been characterized by elemental analysis, i.r. and reflectance spectral studies, and magnetic moment measurements. I.r. spectra show that H₂CPT gives rise to dibasic quadridentate SNNS donor. A square-planar structure is proposed for the copper(II) complex and octahedral for cobalt(II) and nickel(II) complexes according to the magnetic and electronic spectral data. The electrical conductivities of H₂CPT and its CO^II, Ni^II, Cu^II and Cd^II complexes were measured. The positive temperature coefficient (d/dT) and the higher activation energies of H₂CPT and its Cd^II and Cu^II complexes is evidence of their semiconducting character.     

The synthesis,characterization and spectral studies of Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes with N,N-bis(2-{[(2-methyl-2-phenyl-1,3-dioxolan-4-yl) methyl]amino}butyl) N′,N′-dihydroxyethanediimidamide

Co^II, Ni^II, Cu^II, Zn^II and Cd^II complexes of N,N-bis(2-{[(2-methyl-2-phenyl-1,3-dioxolan-4-yl)methyl]amino}butyl)N′,N′-dihydroxyethanediimidamide (LH₂) were synthesized and characterized by elemental analyses, IR, ¹H- and ¹³C-NMR spectra, electronic spectra, magnetic susceptibility measurements, conductivity measurements and thermogravimetric analyses (TGA). The Co^II, Ni^II and Cu^II complexes of LH₂ were synthesized with 1?:?2 metal ligand stoichiometry. Zn^II and Cd^II complexes with LH₂ have a metal ligand ratio of 1?:?1. The reaction of LH₂ with Co^II, Ni^II, Cu^II, Zn^II and Cd^II chloride give complexes Ni(LH)₂, Cu(LH)₂, Zn(LH₂)(Cl)₂, Cd(LH₂)(Cl)₂, respectively.     

Coordination compounds derived from transition metal salts and bis(3,5-dimethylpyrazolyl)methane

Summary The preparation of transition metal complexes containing the sterically hindered ligand, bis(3,5-dimethylpyrazolyl)methane (LL) is described. Compounds of formula M(LL)X₂ (M = Co^II, Ni^II or Zn^II and X = Cl^– or Br^–) or M(LL)₂X₂ (M = Mn^II, Fe^II, Co^II, Ni^II, Cu^II, Zn^II or Cd^II and X = ClO ₄ ^– ; M = Co^II, Ni^II, Cu^II or Zn^II and X = NO ₃ ^– ; M = Ni^II or Cu^II and X = Cl^– or Br^–) have been isolated. In addition, an apparently trimeric Cu₃(LL)₄Cl₆ · EtOH compound is reported. For Ni(LL)Cl₂ a five-coordinated chloro-bridged dimer is found. The perchlorato compounds, M(LL)₂(ClO₄)₂, appear to have one bidentate ClO ₄ ^– and one ionic ClO ₄ ^– group. The M(LL)₂ species appears to occur either in octahedral geometry, leaving twocis-positions free, or in a tetrahedral geometry without space for other ligands, and probably also in a five-coordinate geometry with one free ligand position.Structural conclusions are drawn from i.r., far-i.r. and ligand-field spectra, x-ray powder patterns, magnetic susceptibility data, e.s.r. spectra and conductivity data.     

Structural studies of 4-benzamido-1-o-aminoacetophenone-3-thiosemicarbazone complexes

Summary Complexes of Cu^II, Ni^II, Co^II, Zn^II, Cd^II and Hg^II with 4-benzamido-1-o-aminoacetophenone-3-thiosemicarbazone (H₂BATS) are reported and have been characterized by elemental analyses, molar conductivities, magnetic moments, spectral (visible, i.r.) and thermal (d.t.a., t.g., d.t.g.) measurements. I.r. spectra show that H₂BATS behaves as a dianionic, monoanionic or neutral tetradentate ligand or as a monoanionic tridentate ligand. [Cu₂(H₂BATS)Cl₂]·2H₂O and [Cu₂(H₂BATS)Ac₂]·2H₂O complexes are diamagnetic while [Co(HBATS)OH]·2H₂O and [Ni(HBATS)OH]·2H₂O are octahedral. All the complexes are non-electrolytes. Generally, the solid metal acetate complexes have a unique decomposition exotherm profile which can be used as a rapid and sensitive tool for the detection of acetate-containing complexes.     

Mixed benzohydroxamato-acetylacetonato metal complexes: spectral,thermal and photochemical behaviour

Summary Bis(acetylacetonato)VO^II,–Co^II,–Ni^II,–Cu^II,–Zn^II, –UO ₂ ^II and tris(acetylacetonato)Fe^III react with benzohydroxamic acid to yield the corresponding mixed ligand complexes as a result of displacement of one acetylacetone molecule. Intermolecular association may be the reason for six-coordination geometry around the metal ions. A t.g.a. study of the complexes shows, in most cases, initial loss of alcohol and water molecules associated with the complexes; subsequent decomposition steps are characterised by very sharp weight loss. The photochemical stability of the complexes has been studied. Intraligand excitation causes a decomposition in the case of Fe^III and VO^II-complexes but no detectable effect for Co^II, Ni^II, Cu^II, Zn^II, or UO ₂ ^II -complexes.     

Complexes of 2-furaldehyde 4-phenyl semicarbazone

The synthesis of Co^II, Ni^II, Cu^II and Cd^II complexes of 2-furfural 4-phenyl semicarbazone (FPSC) with stoichiometric formulae: [M(FPSC)₂X₂] (M = Co, Ni or Cu; X = Cl or Br), [CuCl₂(FPSC)] and [(CdCl₂)₂(FPSC)] has been obtained for the first time. The complexes were characterized by elemental analysis, molar conductivity, magnetic measurements, i.r., far i.r. and electronic spectra. FPSC is deduced to act as a bidentate ligand in the Co^II, Ni^II and Cu^II complexes and as a tetradentate one in [(CdCl₂)₂(FPSC)].     

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.     

Studies on the stereochemistry of diphenyl diketone monothio-semicarbazone and its transition metal complexes

Summary The stereochemistry and complexation behaviour of diphenyl diketone monothiosemicarbazone (DKTS) with Cu^II, Co^II, Ni^II, Cd^II, Zn^II, Pd^II, Pt^II, Ru^III, Rh^III and Ir^III have been investigated by means of chemical, magnetic and spectral (i.r., Raman, ¹H- and ¹³C-n.m.r. and electronic) studies. The ligand forms complexes of the M(DKTS)₂ type with Ni^II, Cu^II and Co^II having a distorted octahedral geometry. The absence of a v(M—X) band in the i.r. spectra, coupled with their 1:1 electrolytic conductances, suggests that Ru^III, Rh^III and Ir^III form octahedral complexes of the [M(DKTS)₂]Cl type. A four-coordinate structure involving bridging halides is proposed for the Zn^II, Cd^II, Pd^II and Pt^II complexes, which have relatively low v(M—X) vibration modes.     

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.     

Polymeric complexes of bivalent transition metal ions with 2-hydroxy-1-naphthaldehyde oxaldihydrazone and 2-hydroxy-1-naphthaldehyde malondihydrazone

Summary Polymeric complexes prepared by solid-solution reactions, from 2-hydroxy-1-naphthaldehyde oxaldihydrazone (HNODH) and 2-hydroxy-1-naphthaldehyde malondihydrazone (HNMDH), had the empirical composition M(L-2H)·nH₂O where M=Fe^II, Mn^II, Co^II, Ni^II, Cu^II, Zn^II, Cd^II and Hg^II; L=HNODH, HNMDH andn=0,1, 2. The complexes, which are intensely coloured and insoluble in common organic solvents, were characterized by elemental analysis, magnetic susceptibility, electronic and i.r. spectral data. The absence of anions indicates that the ligands which bind the metal ions from the hydroxyl and the imino groups have been deprotonated.     

Structural features of biologically active coordination compounds of vanillinsemicarbazone

Summary Complexes of vanillinsemicarbazone (VSC) with Mn^II, Fe^II, Co^II, Ni^II, Cu^II, Zn^II, Cd^II and Hg^II have been prepared and characterised by elemental analyses, molar conductance, magnetic susceptibility and spectral data. Probable structures for the complexes are suggested on the basis of their physico-chemical properties. The fungitoxicity of VSC and the isolated complexes have been tested on pathogenic fungi. On leave from the University of Mysore, India.