Manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes with 4-oxo-4H-1-benzopyran-3-carboxaldehyde

The complexes Mn(II), Co(II), Ni(II) and Zn(II) with 4-oxo-4H-1-benzopyran-3-carboxaldehyde were synthesized and characterized by elemental analysis, infrared and UV spectroscopy, X-ray diffraction patterns, magnetic susceptibility, thermal gravimetric analysis, conductivity and also solubility measurements in water, methanol and DMF solution at 298 K. They are polycrystalline compounds with various formula and different ratio of metal ion:ligand. Their formula are following: [MnL₂(H₂O)](NO₃)₂·2H₂O, [CoL₂](NO₃)₂·3H₂O, [NiL₂](NO₃)₂·3H₂O, [CuL₂](NO₃)₂·H₂O and [ZnL₃](NO₃)₂, where L = C₁₀H₆O₃. The coordination of metal ions is through oxygen atoms present in 4-position of γ-pyrone ring and of aldehyde group of ligand. Chelates of Mn(II), Co(II), Ni(II) and Cu(II) obey Curie–Weiss law and they are high-spin complexes with the weak ligand fields. The thermal stability of analyzed complexes was studied in air at 293–1,173 K. On the basis of the thermoanalytical curves, it appears that thermal stability of anhydrous analysed chelates changed following: Cu (423 K) < Zn (438 K) ~ Co (440 K) < Ni (468 K). The gaseous products of thermal decomposition of those compounds in air atmosphere are following: CO₂, CO, NO₂, N₂O, hydrocarbons and in case of hydrates also water. The molar conductance data confirm that the all studied complexes are 1:2 electrolytes in DMF solution.     

Acetylsalicylhydroxamic acid and its cobalt(II), nickel(II), copper(II) and zinc(II) complexes

Acetylsalicylhydroxamic acid (AcSHA) was prepared and characterized. Its pK_a value was determined as 7.78. Solid metal complexes of AcSHA were also prepared and characterized by elemental analysis, electronic and i.r. spectroscopies, and by magnetic moment measurements. The shift of both hydroxamic and acetyl carbonyl vibrations to lower frequencies clearly indicates that AcSHA is bonded through oxygen atoms to the metal ions as a tridentate ligand. On the basis of the experimental data, structures for the complexes are purposed.     

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.     

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.     

Stability studies on 1:1 or 1:3 stoichiometry complexes of hexaza tripods with zinc(II), copper(II), nickel(II) and cobalt(II)

The coordination properties of two C₃-symmetry hexaza tripods, 1,3,5-tri(2,5-diazahexyl)benzene (L1) and 1,3,5-tri(2,5-diazaheptyl)benzene (L2), towards Zn²⁺, Cu²⁺, Ni²⁺ and Co²⁺ ions, studied by potentiometric techniques, are reported. Both ligands form quite stable complexes either in a 1:1 or 1:3 M:L stoichiometry, presenting a preferential coordination order: Zn²⁺ < Cu²⁺ > Ni²⁺ > Co²⁺. It is observed that the different configurations of metal complexes are achieved due to the fact that tripodal ligands are flexible and not constrained into a rigid geometry.     

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.     

N-acetyl-DL-leucinate cobalt(II), nickel(II) and zinc(II) complexes

Summary Complexes of the type M(AcLeu)₂ · B₂ (M = Co^II, Ni^II or Zn^II; B = H₂O, py, 3-pic, 4-pic; AcLeu =N-acetyl-DL-leucinate ion) and M(AcLeu)₂ B (M = Co^II or Zn^II and B = o-phen) were prepared and investigated by means of magnetic and spectroscopic measurements. The i.r. spectra of all the complexes are consistent with bidentate coordination of the amino acid to the metal ion. The room temperature solid state electronic spectra indicate that the symmetry of this species is closer toD _4h and that MO₆ and MO₄N₂ chromophores are present in the M(AcLeu)₂ · 2 H₂O and M(AcLeu)₂B_n · x H₂O (B = py, 3-pic, 4-pic, n=2 and x=0 for M = Ni^II; B = o-phen, n=1 and x=0 for M = Co^II; B = py, 3-pic, 4-pic, n=1 and x=1 for M = Co^II) complexes, respectively. By comparing the Dq values of the amino acid and those of other N-substituted amino acids previously studied, a spectrochemical series of the the cobalt(II) and nickel(II) complexes is proposed. The¹ H n.m.r. spectra of the zinc(II) complexes confirm the proposed stereochemistry.     

Separation and structural studies of manganese(II), cobalt(II), nickel(II), copper(II) and cadmium(II) complexes of benzilic and mandelic esters

Summary Solid metal complexes of benzilic and mandelic esters have been prepared and their structure elucidated using vis., i.r., n.m.r. and e.s.r. spectra. The results of elemental analysis are commensurate with the proposed formulae. Spectral studies indicate that the Ni complexes are octahedral, whereas the Co and Cu analogoues are distorted octahedral.     

Synthesis of four new vic-dioximes and their nickel(II), cobalt(II), copper(II) and cadmium(II) complexes

Four unsymmetrical vic-dioximes: [L¹H₂] N-(4-butylphenyl)amino-amphi-glyoxime, [L²H₂] N-(4-butylphenyl)amino-anti-glyoxime, [L³H₂] N-(4-phenylazophenyl)amino-amphi-glyoxime and [L⁴H₂] N-(4-phenylazophenyl)amino-anti-glyoxime have been prepared from amphi-chloroglyoxime, anti-chloroglyoxime, 4-butylaniline and 4-(phenylazo)aniline respectively. The complexes of these vic-dioximes with Ni^II, Co^II, Cu^II and Cd^II ions have been investigated. All are insoluble in common solvents. Their i.r. spectra and elemental analyses are given, together with mass and ¹H-n.m.r. spectra of the ligands.     

Spectral studies on cobalt(II), nickel(II) and copper(II) complexes of naphthaldehyde substituted aroylhydrazones

A series of new coordination complexes of cobalt(II), nickel(II) and copper(II) with two new aroylhydrazones, 2-hydroxy-1-naphthaldehyde isonicotinoylhydrazone (H(2)L(1)) and 2-hydroxy-1-naphthaldehyde-2-thenoyl-hydrazone (H(2)L(2)) have been synthesized and characterized by elemental analysis, conductance measurements, magnetic susceptibility measurements, (1)H NMR spectroscopy, IR spectroscopy, electronic spectroscopy, EPR spectroscopy and thermal analysis. IR spectra suggests ligands acts as a tridentate dibasic donor coordinating through the deprotonated naphtholic oxygen atom, azomethine nitrogen atom and enolic oxygen atom. EPR and ligand field spectra suggests octahedral geometry for Co(II) and Ni(II) complexes and a square planar geometry for Cu(II) complexes.     

Synthesis and structural studies of 2-acetylthiophene-2-thenoylhydrazone complexes of oxovanadium(IV), manganese(II), cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II) and mercury(II)

Complexes with chemical compositions VO(Hatth)₂SO₄, VO(Hatth)₂SO₄·py, [M(Hatth)₂Cl·H₂O]Cl [M = Mn(II), Co(II) and Ni(II)], [Cu(Hatth)₂Cl]₂Cl₂, [Cu(Hatth)₂· Cl·py]Cl, [Cd(Hatth)₂Cl]Cl, M(Hatth)₂Cl₂ [M = Zn(II) and Hg(II)], VO(atth)₂, VO(atth)₂py, M(atth)₂(py)₂ [M = Mn(II) and Cu(II)], M(atth)₂(H₂O)₂ [M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)], Hatth = 2-acetylthiophene-2-thenoylhydrazone, and atth, its deprotonated form, have been prepared and characterized by analytical data, molar conductance, magnetic susceptibility, electronic and photoacoustic, ESR, IR and NMR spectral studies. X-ray diffraction study has been used to determine the shape and the dimensions of the unit lattice of copper(II) complexes.     

Thermodynamic studies of dynamic metal ligands with copper(II), cobalt(II), zinc(II) and nickel(II)

The self-assembly of unsymmetrical metal ligands from simpler components circumvents complex synthetic approaches. We show herein how a recently developed three-component assembly to create tripicolylamine-like ligands can be extended to the use of azides rather than pyridines. Substituent effects, metal dependence, and reversibility of the assembly are explored. Further, we show that the extent of assembly directly correlates with the differential binding of the templating metals between dipicolylamine-like and tripicolyamine-like ligands.     

2-thiouracil-based cobalt(II), nickel(II) and copper(II) complexes

Summary Cobalt(II), nickel(II) and copper(II) complexes of 2-thiouracil and its arylazo derivatives were prepared. The elemental analysis suggest a range of 11, 21 and 13 stoichiometries. Electronic spectra and magnetic susceptibility measurements were used to infer the structures and the i.r. spectra of the ligands and their complexes to identify the type of bonding.     

Synthesis and physico-chemical studies on cobalt(II), nickel(II) and copper(II) complexes of benzidine diacetyloxime

The synthesis of benzidine diacetyloxime (H₂L) and its cobalt(II), nickel(II) and copper(II) complexes is described. The complexes were characterized by elemental analyses, molar conductivities, magnetic moments, i.r., u.v.–vis. spectra, t.g.a. and e.s.r. measurements. I.r. spectra show that H₂L behaves as a neutral or dinegative ligand depending on the nature of the metal salts. The molar conductances of the complexes in DMF are commensurate with their non-ionic character. The e.s.r. spectrum of the solid copper(II) complex (7) at room temperature shows broad signal, indicating spin-exchange interactions between copper(II) ions. However, in TMHF solution at 77 K, it shows an axial type ground state with mixed ionic-covalent bond character.     

Metal-ion directed synthesis of binuclear octaazamacrocyclic complexes of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) and their physico-chemical studies

A novel series of 16-membered binuclear complexes of octaazatetraimine ligand, [M = Mn^II, Co^II, Ni^II, Cu^II and Zn^II; X = Cl or NO₃] have been synthesized by metal template condensation reactions of o-phenylenediamine with N,N′-diacetylhydrazine in 1:1:1 molar ratio in methanol. The proposed stoichiometry and the bonding of the macrocyclic moiety to metal ions along with the overall stereochemistry have been derived from the results of elemental analyses, magnetic susceptibility, conductivity data and the spectral data revealed from FT-IR, , ESI mass, UV–visible studies. An octahedral geometry has been envisaged for Mn^II, Co^II, and Ni^II complexes while a slight distortion in octahedral geometry has been noticed for Cu^II complexes. The low conductivity data of all the complexes suggest their non-ionic nature.     

Synthesis,spectral, thermal,and magnetic studies of cobalt(II), nickel(II), copper(II), zinc(II), and cadmium(II) complexes with N2O2 donor groups

A new Schiff base ligand was prepared by condensation of 2-hydroxy-4-methoxybenzaldehyde with 1,2-propanediamine. The ligand and its metal complexes were characterized by elemental analysis, FT-IR, ¹H and ¹³C NMR, magnetic moment, molar conductance, UV-Vis, SEM and thermal analysis (TGA). The molar conductance measurements indicated that all the metal complexes were non-electrolytes. IR spectra showed that ligand (L) behaves as a neutral tetradentate ligand and binds to the metal ions by the two azomethine nitrogen atoms and two phenolic oxygen atoms. The electronic absorption spectra and magnetic susceptibility measurements indicated square planar geometry for the Ni(II) and Cu(II) complexes while other metal complexes showed tetrahedral geometry. Also the surface morphology of the complexes was studied by SEM.     

N-Phthaloylglycinate ternary complexes with cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) metal ions and aromatic mono,bi and tridentate amines

Complexes of N-phthaloylglycinate (N-phthgly) and Co^II, Ni^II, Cu^II, Zn^II and Cd^II containing imidazole (imi), N-methylimidazole (mimi), 2,2-bipyridyl (bipy) and 1,10-phenanthroline (phen), and tridentate amines such as 2,2,2-terpyridine (terpy) and 2,4,6-(2-pyridyl)s-triazine (tptz), were prepared and characterized by conventional methods, i.r. spectra and by thermogravimetric analysis. For imi and mimi ternary complexes, the general formula [M(imi/mimi)₂(N-phthgly)₂]·nH₂O, where M = Co^II, Ni^II, Cu^II and Zn^II applies. For Cd^II ternary complexes with imi, [Cd(imi)₃(N-phthgly)₂]·2H₂O applies. For the bi and tridentate ligands, ternary complexes of the formula [M(L)(N-phthgly)₂]·nH₂O were obtained, where M = Co^II, Ni^II, Cu^II and Zn^II; L = bipy, phen, tptz and terpy. In all complexes, N-phthgly acts as a monodentate ligand, coordinating metal ions through the carboxylate oxygen, except for the ternary complexes of Co^II, Ni^II and Cu^II with mimi and Cu^II and Zn^II with imi, where the N-phthgly acts as a bidentate ligand, coordinating the metal ions through both carboxylate oxygen atoms.