A study of adduct formation of heterocyclic nitrogen bases with nickel(II) chelate of di(6-chloro-2-methylphenyl)carbazone

The study of the adduct formation of Ni(II) di(6-chloro,2-methylphenyl)carbazonate has been undertaken by synthesising and characterizing it by magnetic susceptibility, UV-VIS, IR and 1H-NMR spectral measurements. The distorted square planar Ni(II) chelate forms adducts with heterocyclic nitrogen bases; spectrophotometric method has been employed for the study of the adduct formation in a monophase chloroform. Both bidentate and unsaturated monodentate heteronuclear nitrogen bases form hexacoordinated adducts with 1:1 and 1:2 stoichiometry, respectively (metalchelate:base). However, the saturated nitrogen bases form pentacoordinated adducts with 1:1 stoichiometry. The results are discussed in terms of basicity and steric factors of the bases.     

Synthesis of nickel(II)-di(2,3-dichlorophenyl)carbazonate and its adduct formation with heterocyclic nitrogen bases

The nickel(II)-di(2,3-dichlorophenyl)carbazonate [Ni(D2,3DClPC)₂] complex has been prepared and characterized by elemental and spectral studies. The Ni^II chelate forms adducts with heterocyclic nitrogen bases, which were studied spectrophotometrically in monophase CHCl₃ media. Saturated monodentate bases such as pyrrolidine, piperidine, etc., form pentacoordinate adducts of 1:1 stoichiometry, whereas bidentate and unsaturated monodentate bases form hexacoordinated adducts with 1:1 and 1:2 metal–ligand stoichiometries respectively. The results are discussed interms of steric properties, basicity and ring structures of the heterocyclic bases.     

Synthesis of nickel(II)-di(5-chloro-2-methylphenyl)carbazonate and its adduct formation with heterocyclic nitrogen bases

Summary The title complex has been synthesized and characterized by elemental and spectral analysis. The Ni^II chelate forms adducts with heterocyclic nitrogen bases, which were characterized spectrophotometrically in solution. Bidentate and unsaturated monodentate bases form hexacoordinate adducts with 11 and 12 metalligand stoichiometries, respectively, whilst saturated nitrogen bases form pentacoordinate adducts with 11 stoichiometry. The results are discussed in terms of basicities and steric properties of the bases.     

Heterocyclic nitrogen base adducts of nickel(II)–di(2,4-dibromophenyl)carbazonate

The title complex was prepared and characterized by elemental and spectral analyses. The formation constants of various heterocyclic nitrogen base adducts with the Ni^II–di(2,4-dibromophenyl)carbazonate have been determined in a monophase by spectrophotometry at 25 ± 0.1 °C. The monodenatate and bidentate bases form penta- and hexa-coordinated adducts respectively with 1:1 stoichiometry for the metal chelate-base, whereas the unsaturated monodentate bases form hexa-coordinated adducts with 1:2 stoichiometry. The behaviour of saturated heterocyclic bases such as pyrrolidine, piperidine, hexamethyleneimine and morpholine towards the metal chelate has been studied, and the results are discussed in terms of steric hindrance, basicity and ring structure.     

A spectroscopic study of adducts of heterocyclic nitrogen bases with nickel(II) chelates of 2-methyl-5-nitrophenylthiocarbazone

A spectrophotometric method was employed to study the adduct formation constants of a few typical bases with nickel(II) chelates of 2-methyl-5-nitrophenylthiocarbazone. Monobasic bases such as pyridine and methyl-substituted pyridines form pentacoordinated adducts with a stoichiometry of 1:1 for metal chelate-base. The dibasic bases such as 1,10-phenanthroline, 2,2′-bipyridyl, etc. also exhibit 1:1 stoichiometry giving hexacoordinated adducts. The experimental results are discussed in terms of the basicity and steric factors of the various bases.     

Spectroscopic study of the equilibrium of adduct formation by acetylacetonates of oxovanadium(IV) and copper(II) with nitrogen bases

Equilibrium constants have been determined at room temperature for the 1:1 addition of nitrogen bases to oxovanadium(IV) acetylacetonate and to copper(II) acetylacetonate in methylene chloride solution. Variation of stability of the adducts due to changing bases are attributed in part to change in donor power and in part to steric effects. IR and PMR data obtained for aminopyridines complexed totally or partially with oxovanadium(IV) acetylacetonate indicate coordination of all these bases but 2-amino-6-methylpyridine through the heterocyclic nitrogen. The results obtained for the 2-amino-6-methylpyridine-oxovanadium(IV) acetylacetonate system show that the vanadium atom coordinates with the primary amino group.     

Complex formation of copper(II) and nickel(II) with N-arylthiopicolinamides

The reactions of N-arylthiopicolinamides (HL) with copper(II) and nickel(II) ions in organic and aqueous-organic solutions were studied. On addition of HCl, the transformation of ML₂ complexes into M(HL)Cl₂ occurs, while the reverse reaction takes place under the action of amphoteric protic solvents. The structures of the isolated complexes were established by IR and UV spectroscopy.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1546–1550, September, 1993.     

Synthesis and characterization of 3-amino-5-methylisoxazole Schiff bases and their complexes with copper(II), nickel(II) and cobalt(II)

Schiff bases obtained by condensing 3-amino-5-methylisoxazole with salicylaldehyde, 2,3-dihydroxybenzaldehyde, 2,4-dihydroxy-benzaldehyde, 2,5-dihydroxybenzaldehyde or o-hydroxynaphthaldehyde were obtained and characterized by C, H, N analysis, mass, NMR and IR spectra. Copper, nickel and cobalt complexes of the Schiff bases were prepared and characterized using elemental analysis, conductivity measurements, magnetic moments, IR, UV-VIS and ESR spectra, X-ray diffraction, TGA, DTA and DSC thermal analysis. All the complexes are non-electrolytes. ESR spectra show isotropic as well as axial symmetry for the copper complexes. Thermal studies support the formulation of these complexes and showed that they decompose in two or three steps depending on the metal used. Activation energy E _a and enthalpies ΔH associated with the decomposition process were calculated and correlated with the complexed metal used.     

Investigation of the oxygen affinity of manganese(II), cobalt(II) and nickel(II) complexes with some tetradentate Schiff bases

Oxygen absorption–desorption processes for square planar Mn(II), Co(II) and Mn(II) complexes of tetradentate Schiff base ligands in DMF and chloroform solvents were investigated. The tetradentate Schiff base ligands were obtained by condensation reaction of ethylenediamine with salcyldehyde, o-hydroxyacetophenone or acetylacetone in the molar ratio 1:2. The square planar complexes were prepared by the reaction of the Schiff base ligands with Mn(II) acetate, Co(II) nitrate and Ni(II) nitrate in dry ethanol under nitrogen atmosphere. The sorption processes were undertaken in the presence and absence of (pyridine) axial-base in 1:1 M ratio of (pyridine:metal(II) complexes). Complexes in DMF indicate significant oxygen affinity than in chloroform solvent. Cobalt(II) complexes showed significant sorption processes compared to Mn(II) and Ni(II) complexes. The presence of pyridine axial base clearly increases oxygen affinity.     

Stereoselective adduct formation of α-acylcamphorato-copper(II) chelates with some chiral Lewis bases

The formation constants of the mono-adducts of α-acylcamphorato-copper(II) chelates such as (+)-Cu(facam)₂, (?)-Cu(facam)₂, (+)-Cu(hfbc)₂ and (?)-Cu(hfbc)₂ with some chiral Lewis bases were determined spectrophotometrically in benzene. In order to compare the adduct formation constants obtained with the (+)- and (?)-forms, some pairs of chiral Lewis bases such as 1-amino-2-propanol [(R)(?), (S)(+)], 1-(α-naphthyl)ethylamine [(R)(+), (S)(?)], α-phenyl ethylamine [(R)(+), (S)(?)] and also quinine and quinidine were examined as neutral ligands. Although not very pronounced, the effects of combinations obtained for (+)- or (?)-Cu(II) chelates and (+)- or (?)-ligands indicate that formation constants obtained by the formation of adducts with the ligands having different directions of the optical rotation seems to be superior to those with the same direction.     

Nickel(II) complexes of substituted diphenylcarbazones and their adducts with heterocyclic nitrogen bases

The complexing behaviour of novel 1,5-di(4-chloro-2- methylphenyl)carbazone and 1,5-di(2,4-dichlorophenyl)carbazone towards nickel(II) ions has been investigated by elemental analysis, magnetic susceptibility, u.v. -vis., i.r. and 1H-n.m.r. spectral studies. The ligands act as bidentate N,O donors and form 1:2 complexes with the metal ions. The adducting behaviour of nickel(II) complexes with nitrogen bases has been studied spectrophotometrically in a chloroform monophase. The nickel(II) di(4-chloro-2-methylphenyl)carbazonate forms hexacoordinate adducts with monodentate and bidentate bases with 1:2 and 1:1 chelate:base stoichiometries, respectively, whilst, nickel(II) di(2,4-dichloro-phenyl)carbazonate forms penta- and hexacoordinate adducts of 1:1 chelate:base stoichiometry with monodentate and bidentate bases, respectively. The results are discussed on the basis of steric properties and the basicity of the nitrogen bases.     

Thermodynamics of formation of nitrogen bases and d-ribose from mineral substances in light of the problem of origination of simplest elements of living matter

The paper represents a further development of our hydrate hypothesis of simplest living matter origination (SLMO) from inorganic and simplest organic mineral substances. It is supposed that the sources of SLMO are simplest aliphatic hydrocarbons, niters, and phosphates. Thermodynamic calculations demonstrating a principal possibility for simultaneous syntheses of different nitrogen bases, d-ribose, and desoxy-d-ribose from these source substances are presented. The most probable principal mechanism of SLMO and the principal conditions necessary for realization of the proposed chemism of SLMO in the framework of the proposed mechanism are considered. A principal means for testing the hypothesis is proposed.     

Synthesis,characterization, and antimicrobial activity of cobalt(II), nickel(II), copper(II) and zinc(II) complexes with ferrocenyl Schiff bases containing a phenol moiety

Three ferrocenyl Schiff bases containing a phenol moiety have been formed by 1:1 molar condensation of acetylferrocene with 2‐aminophenol, 2‐amino‐5‐picoline or 2‐amino‐5‐chlorophenol. These ligands form 2:1 complexs with cobalt(II), copper(II), nickel(II), and zinc(II) ions. From the different spectral data, it was found that coordination of the ligands with the metal ions takes place via the azomethine nitrogen atoms and the deprotonated oxygen of the phenol groups. These ligands and their complexes have been characterized by IR, ¹H NMR, ¹³C NMR, UV–Vis spectra, and elemental analysis. The spectral data of the ligands and their complexes are discussed in connection with the structural changes due to complexation. The complexes prepared showed good antimicrobial activity against Escherichia coli, Bacillus subtilus, and Candida albicans. Copyright © 2004 John Wiley & Sons, Ltd.     

Complex formation of polyethyleneimine with copper(II), nickel(II), and cobalt(II) ions

An influence of the structure of a globule of polyethyleneimine on the complex formation of one with the copper(II), nickel(II), and cobalt(II) ions is described. A change of the coordination number from the pH of solution for complexes of ethylenediamine, diethylenetriamine, and polyethyleneimine with metal ions was found. The fraction of monomer links, bound with metal ions, depends on the volume of the globule of macromolecule as well as the condition of the proceeding reaction. The reaction of complex formation is controlled by the diffusion of metal ions into the polymer globule in solution. The effective equilibrium constants of complex formation were found. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 914–922, 2002; DOI 10.1002/pola.10157     

Spectral and thermal study on the adduct formation between square planar nickel(II) chelates and some bidentate ligands

Adducts of Ni(II)-square planar complexes [Ni(beta-dik)(Me(4)en)](+), with a series of bidentate ligands (L), where beta-dik=acetylacetonate (acac) and benzoylacetonate (bzac), Me(4)en=N,N,N',N'-tetramethylethylenediamine and L=Me(4)en, 2,2'-bipyridine (bipy), ethylenediamine (en) and oxalate (C(2)O(4)(2-)) have been synthesized and characterized by spectral, thermal and magnetic measurements. Formation constants of the adducts formed from a series of ternary mixed Ni(II) complexes with the general formula [Ni(beta-dik)(diam)](+) with 1,10-phenanthroline (phen), 2,2'-bipyridine (bipy) and pyridine were spectrophotometrically determined. Thermodynamic parameters of the adduct formation between nickel(II) square-planar chelates and pyridine (py), 2,2'-bipyridine (bipy) and acetylacetone (acac) were also spectrophotometrically determined in 1,2-dichloroethane. The thermal stability of the isolated adducts was studied using thermogravimetry and the decomposition schemes of the adducts were given.     

Photooxidation of bis(ethylxanthato)nickel(II) containing aromatic nitrogen heterocyclic ligands in chloroform

The photochemistry of the complexes [Ni(Etxn)₂(N-N)] [Etxn=ethylxanthate,N-N=2,2-bipyridine(bpy), 4,4-dimethyl-2,2-bipyridine (4,4-Me-bpy), 1,10-phenanthroline (phen) or 2,2-bipyrimidine (bpym)] has been investigated. These complexes were not light sensitive in most solvents such as acetonitrile. Upon irradiation of chloroform solutions of these complexes, a photoredox reaction occurred giving the parent Ni(Etxan)₂. It is suggested that the reactive excited state is of the charge-transfer-to-solvent (CTTS) type. The energy of this state depends on the redox potentials of the solvent. When CHCl₃ as solvent was replaced by the stronger oxidant CCl₄, the photoactive wavelength region was shifted to the red. It was blue shifted when the weaker oxidant CH₂Cl₂ was used. From quantum yield measurements it is concluded that the photostability of the studied complexes decreases in the following order:bpym>phen>bpy>4,4-Me-bpy.

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Photooxidation von Bis(ethylxanthato)nickel(II) mit aromatischen Stickstoffheterocyclen enthaltenden Liganden in Chloroform

Zusammenfassung Es wurde die Photochemie der Komplexe [Ni(Etxn)₂(N-N) [Etxn=Ethylxanthat,N-N=2,2-Bipyridin (bpy), 4,4-Dimethyl-2,2-bipyridin (4,4-Me-bpy), 1,10-Phenanthrolin (phen) oder 2,2-bipyrimidin (bpym)] untersucht. Diese Komplexe waren in den meisten Lösungsmitteln wie etwa Acetonitril nicht lichtsensitiv. Bei Bestrahlung von Chloroformlösungen der Komplexe trat jedoch eine Photoreaktion auf, die zum Stammkomplex Ni(Etxn)₂ führte. Es wird vorgeschlagen, für den reaktiven angeregten Zustand einen Charge-Transfer-zu-Lösungsmittel (CTTS)-Typ anzunehmen. Die Energie dieses Zustands hängt vom Redoxpotential des Lösungsmittels ab. Bei Ersatz von CHCl₃ als Lösungsmittel durch das stärkere Oxidans CCl₄ wurde die photoaktive Wellenlänge nach Rot verschoben. Eine Blauverschiebung ergab sich hingegen, wenn das schwächere Oxidans CH₂Cl₂ verwendet wurde. Aus Messungen der Quantenausbeuten ergab sich die folgende Ordnung nach abnehmender Photostabilität der untersuchten Komplexe:bpym>phen>bpy>4,4-Me-bpy.