Synthesis,characterization, molecular modeling and antimicrobial activity of 2-(2-(ethylcarbamothioyl)hydrazinyl)-2-oxo-N-phenylacetamide copper complexes

Six Cu(II) complexes of 2-(2-(ethylcarbamothioyl)hydrazinyl)-2-oxo-N-phenylacetamide (H₃APET) have been prepared and characterized by elemental analyses, spectral (IR, UV–vis, ¹H NMR and ESR) as well as magnetic and thermal measurements. The data revealed that the ligand acts as ON bidentate, ONS tridentate or ONNS tetradentate forming structure in which each copper atom is a tetrahedral or tetragonal environment. The bond length, bond angle, HOMO, LUMO, dipole moment and charges on the atoms have been calculated to confirm the geometry of the ligand and the investigated complexes. Kinetic parameters were determined for each thermal degradation stage of the Cu(II) complexes using Coats–Redfern and Horowitz–Metzger methods. Moreover, the ligand and its complexes were screened against bacteria Staphylococcus aureus, Escherichia coli, Candida and fungi, Albicans and Aspergillus flavus using the inhibitory zone diameter.     

Synthesis,Characterization and Antifungal Activity of Metal Complexes of 2-(5-((2-Chlorophenyl)Diazenyl)-2-Hydroxybenzylidene) Hydrazinecarbothioamide

Abstract

New metal complexes of Co(II), Cu(II), Ni(II), Zn(II), Mn(II), Fe(III), Ru(III), UO₂(II), and VO(II) with the Schiff base, 2-(5-((2-chlorophenyl)diazenyl)-2-hydroxy- benzylidene) hydrazine-carbothioamide (H₂L) have been prepared and characterized by elemental and thermal analyses, FT-IR, UV–Vis, mass spectra, ¹H-NMR, and ESR as well as conductivity and magnetic moments measurements. The IR spectra showed that the ligand acts as neutral tridentate, neutral bidentate or monobasic tridentate ligand. The geometries of metal complexes were either octahedral or square pyramidal. The ESR spectra of the solid copper(II) complexes indicated an axial symmetry type of a d_(x2-y2) ground state with considerably ionic or covalent environment. The effect of the presence of an azo group on the biological activity of the ligand was investigated. The ligand and its complexes are biologically inactive due to the presence of azo group.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the related elements to view the free supplemental file.     

Synthesis,spectroscopic, biological,and theoretical studies of new complexes from (E)-3-(2-(5, 6- diphenyl-1,2,4- triazin-3- yl)hydrazono)butan-2- one oxime

New mononuclear Fe (III), Cu (II), Ag (I), ZrO ( IV) and UO₂(VI) complexes were synthesized by the reaction of metal ions with (E)-3-(2-(5, 6- diphenyl-1,2,4- triazin-3- yl)hydrazono)butan-2- one oxime. The structures of the metal complexes were characterized using analytical, spectral (infrared, electronic, ¹H NMR, electron spin resonance (ESR), and mass), magnetic moment, molar conductance, thermal gravimetric analysis, and powder X-ray diffraction (XRD) measurements. All complexes have octahedral geometries except the Cu (II) complex, which has square planar geometry, and the UO₂(VI) complex, in which the coordination number is seven. The ligand acts as a (neutral, monoanionic or dianionic) tridentate with N₂O coordinating sites: N-azomethine, N-triazine, and O-oxime. Fluorescence spectral studies were carried out in solid state and in dimethylformamide (DMF). The kinetic parameters of the thermal decomposition stages were calculated using Coats–Redfern equations. The morphological structures of the ligand and some complexes were determined using XRD. The molecular orbital calculations were carried out for the ligand and metal complexes using the Hyperchem 7.52 program on the basis of the PM3 level. The antimicrobial activities of the ligand and its complexes were investigated towards the microorganisms S. aureus and B. subtilis as Gram-positive bacteria, S. typhimurium and E. coli as Gram-negative bacteria, C. albicans, and A. fumigatus. The ligand and its complexes showed antitumor activity against Hep G-2 cell lines, where Cu (II) and Ag (I) complexes seem to be promising as they showed IC₅₀ values that are lower than and comparable to that of the antitumor drug doxorubicin.     

Copper(II) and molybdenum(VI) complexes with 5-bromosalicylaldehyde S-allylisothiosemicarbazone: Syntheses,characterizations and crystal structures

A new tridentate Schiff base, 5-bromosalicylaldehyde S-allylisothiosemicarbazone hydrobromide (H₂L), and several new mononuclear complexes of copper(II) and molybdenum(VI) of this ligand with general formulas ([Cu(L)Im] (1)), ([Cu(L)NH₃]·4H₂O (2)), and ([MoO₂(L)1-MeIm] (3), Imidazole: Im, 1-methylimidazole: 1-MeIm) were prepared and characterized by elemental analyses, IR, proton magnetic resonance Spectroscopy, and ultraviolet–visible techniques. The physico-chemical results suggested that the H₂L coordinates in the dianionic tridentate form. Crystal structures of the Cu(II) complexes reveal a square planar configuration surrounded by the dianionic tridentate isothiosemicarbazone (ONN) and Im and NH₃ for 1 and 2, respectively. The L^2-, two oxo, and 1-methylimidazole are coordinated to molybdenum(VI) in a distorted octahedral geometry in 3. Formation of pure metal oxide residues was confirmed by thermal degradation of the complexes.     

Synthesis, spectroscopic characterization and thermal behavior of metal complexes formed with N'-(1-(4-hydroxyphenyl) ethylidene)-2-oxo-2-(phenylamino) acetohydrazide (H3OPAH)

Complexes of Co(II), Ni(II), Cu(II), Mn(II), Cd(II), Zn(II), Hg(II) and U(IV)O(2)(2+) with N'-(1-(4-hydroxyphenyl) ethylidene)-2-oxo-2-(phenylamino) acetohydrazide (H(3)OPAH) are reported and have been characterized by various spectroscopic techniques like IR, UV-visible, (1)H NMR and ESR as well as magnetic and thermal (TG and DTA) measurements. It is found that the ligand behaves as a neutral bidentate, monoanionic tridentate or tetradentate and dianionic tetradentate. An octahedral geometry for [Mn(H(3)OPAH)(2)Cl(2)], [Co(2)(H(2)OPAH)(2)Cl(2)(H(2)O)(4)] and [(UO(2))(2)(HOPAH)(OAc)(2)(H(2)O)(2)] complexes, a square planar geometry for [Cu(2)(H(2)OPAH)Cl(3)(H(2)O)]H(2)O complex, a tetrahedral structure for [Cd(H(3)OPAH)Cl(2)], [Zn(H(3)OPAH)(OAc)(2)] and [Hg(H(3)OPAH)Cl(2)]H(2)O complexes. The binuclear [Ni(2)(HOPAH)Cl(2)(H(2)O)(2)]H(2)O complex contains a mixed geometry of both tetrahedral and square planar structures. The protonation constants of ligand and stepwise stability constants of its complexes at 298, 308 and 318 K as well as the thermodynamic parameters are being calculated. The bond lengths, bond angles, HOMO, LUMO and dipole moments have been calculated to confirm the geometry of the ligand and the investigated complexes. Also, thermal properties and decomposition kinetics of all compounds are investigated. The interpretation, mathematical analysis and evaluation of kinetic parameters (E(a), A, ΔH, ΔS and ΔG) of all thermal decomposition stages have been evaluated using Coats-Redfern and Horowitz-Metzger methods.     

Thermal and spectral studies of 5-(phenylazo)-2-thiohydantoin and 5-(2- hydroxyphenylazo)-2-thiohydantoin complexes of cobalt(II), nickel(II) and copper(II)

Complexes of 5-(phenylazo)-2-thiohydantoin (L¹) and 5-(2-hydroxyphenylazo)-2-thiohydantoin (HL²) with Co(II), Ni(II) and Cu(II) salts have been synthesised and characterized by elemental analysis, conductivity, magnetic susceptibility, UV-Vis, IR, ESR and TG studies. The magnetic and spectral data suggested octahedral geometry for [L¹M(OAc)₂(H₂O)₂]·xH₂O {M=Ni^ll and Cu^ll} and [L¹CuCl₂(H₂O)]·H₂O (dimeric form for the latter), trigonal bipyramidal geometry for [L²Co(OAc)(H₂O)]·2H₂O, square pyramidal geometry for [L²Ni(OAc)(H₂O)]·H₂O and square planar geometry for [L²CuCl]·2H₂O. TG studies confirmed the chemical formulations of these complexes and showed that their thermal degradation takes place in three to five steps, depending on the type of the ligand and the geometry of the complex. The kinetic parameters (n, E^#, A, ΔH^#, ΔS^# and ΔG^#) of the thermal decomposition stages were computed using the Coats-Redfern and other standard equations and are discussed.     

Molecular modeling,spectral, and biological studies of 4-formylpyridine-4 N-(2-pyridyl) thiosemicarbazone (HFPTS) and its Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Cd(II), Hg(II), and UO2(II) complexes

The present work describes the preparation and characterization of some metal ion complexes derived from 4-formylpyridine-⁴ N-(2-pyridyl)thiosemicarbazone (HFPTS). The complexes have the formula; [Cd(HFPTS)₂H₂O]Cl₂, [CoCl₂(HPTS)]·H₂O, [Cu₂Cl₄(HPTS)]·H₂O, [Fe (HPTS)₂Cl₂]Cl·3H₂O, [Hg(HPTS)Cl₂]·4H₂O, [Mn(HPTS)Cl₂]·5H₂O, [Ni(HPTS)Cl₂]·2H₂O, [UO₂(FPTS)₂(H₂O)]·3H₂O. The complexes were characterized by elemental analysis, spectral (IR, ¹H-NMR and UV–Vis), thermal and magnetic moment measurements. The neutral bidentate coordination mode is major for the most investigated complexes. A mononegative bidentate for UO₂(II), and neutral tridentate for Cu(II). The tetrahedral arrangement is proposed for most investigated complexes. The biological investigation displays the toxic activity of Hg(II) and UO₂(II) complexes, whereas the ligand displays the lowest inhibition activity toward the most investigated microorganisms.     

Rhenium(I) and technetium-99m(I) fac-tricarbonyl complexes with 4-(imidazolin-2-yl)-3-thiabutanoic acid derivatives as tridentate ligands: Synthesis and structural characterization

Two rhenium(I) tricarbonyl complexes, with the monoanionic tridentate NSO type ligand, 4-(imidazolin-2-yl)-3-thiabutanoic acid and 4-(N-ethylimidazolin-2-yl)-3-thiabutanoic acid were synthesized and isolated in pure form. Both complexes were characterized by spectroscopic methods and elemental analysis. The solid-state structure of 4-(imidazolin-2-yl)-3-thiabutanoic acid and of both complexes was established by X-ray crystallography. The geometry about the rhenium is octahedral. The analogous technetium-99m complexes were also prepared quantitatively by the reaction of both ligands with the fac-[^99mTc(CO)₃(H₂O)₃]⁺ synthon and their identity was established by chromatographic comparison to their rhenium congeners.     

Synthesis and magnetic,spectral and thermal eukaryotic DNA studies of some 2-acetylpyridine- [N-(3-hydroxy-2-naphthoyl)] hydrazone complexes

Complexes of Ni(II), Co(II), Cu(II), Zn(II), Cd(II), Hg(II) and U(VI)O₂ with 2-acetylpyridine-[N-(3-hydroxy-2-naphthoyl)] hydrazone (H₂APHNH) have been prepared and characterized by elemental analysis, molar conductance, thermal (TG, DTG), spectral (¹H NMR, IR, UV–Vis, ESR) and magnetic measurements. ¹H NMR spectrum of the ligand suggests the presence of intramolecular hydrogen bonding. IR spectra show that H₂APHNH is a bidentate, tridentate and/or tetradentate ligand. Thermal decomposition of some complexes ended with metal oxide as a final product. ESR spectra gave evidence for the proposed structure and the bonding for some Cu(II) complexes. Biological activity measurements were carried out.     

Synthesis,Spectroscopic and Magnetic Studies on Metal Complexes of 5-Methyl-3-(2-Hydroxyphenyl)Pyrazole

A tridentate ONN donor ligand, 5-methyl-3-(2-hydroxyphenyl)pyrazole; H₂L, was synthesized by reaction of 2-(3-ketobutanoyl)phenol with hydrazine hydrate. The ligand was characterized by IR, ¹H NMR and mass spectra. ¹H NMR spectra indicated the presence of the phenolic OH group and the imine NH group of the heterocyclic moiety. Different types of mononuclear metal complexes of the following formulae [(HL)₂M][sdot]xH₂O (M=VO, Co, Ni, Cu, Zn and Cd), [(HL)₂M(H₂O)₂] (M=Mn and UO₂) and [(HL)LFe(H₂O)₂] were obtained. The Fe(III) complex, [(HL)LFe(H₂O)₂] undergoes solvatochromism. Elemental analyses, IR, electronic and ESR spectra as well as thermal, conductivity and magnetic susceptibility measurements were used to elucidate the structures of the newly prepared metal complexes. A square-pyramidal geometry is suggested for the VO(IV) complex, square-planar for the Cu(II), Co(II) and Ni(II) complexes, octahedral for the Fe(III) and Mn(II) complexes and tetrahedral for the Zn(II) and Cd(II) complexes, while the UO₂(VI) complex is eight-coordinate. Transmetallation of the UO₂(VI) ion in its mononuclear complex by Fe(III), Ni(II) or Cu(II) ions occurred and mononuclear Fe(III), Ni(II) and Cu(II) complexes were obtained. IR spectra of the products did not have the characteristic UO₂ absorption band and the electronic spectra showed absorption bands similar to those obtained for the corresponding mononuclear complexes. Also, transmetallation of the Ni(II) ion in its mononuclear complex by Fe(III) has occurred. The antifungal activity of the ligand and the mononuclear complexes were investigated.     

Synthesis,Spectral and Magnetic Studies of Mononuclear and Binuclear Mn(Ii), Co(Ii), Ni(Ii) and Cu(Ii) Complexes with Semicarbazone Ligands Derived from Sulfonamide

Mononuclear and binuclear Mn(II), Co(II), Ni(II) and Cu(II) complexes of new semicarbazone ligands derived from sulfonamide were synthesized and characterized by elemental analysis and IR spectra. In mononuclear complexes, the semicarbazone behaves as a monoanionic terdentate or neutral terdentate ligand towards the metal ion. However, in binuclear complexes, it behaves as a monoanionic terdentate towards one of the bivalent metal ions and monoanionic bidentate ligand towards the other metal ion in the same complex. Electronic spectra and magnetic susceptibility measurements of the solid complexes indicated octahedral geometry around Mn(II), Co(II) and Ni(II) and square planar around the Cu(II) ion. These geometries were confirmed by the results obtained from thermal analyses. The antifungus properties of the ligands and their complexes were investigated.     

Synthesis, spectral and thermal studies of new copper (II) complexes with 1,2-di(imino-2-aminomethylpyridil)ethane

New copper (II) complexes of Schiff bases with 1,2-di(imino-2-aminomethylpyridil)ethane with the general composition CuLX _m (H₂O) _x , [L = Schiff base, X = Cl^?, Br^?, NO₃ ^?, ClO₄ ^?, CH₃COO^?, m = 2; X = SO₄ ^2?, m = 1] were prepared by template synthesis. The complexes were characterized by elemental analysis, conductivity measurements, magnetic moments, IR, UV–VIS and EPR spectra. The thermal behavior of complexes was studied using thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Infrared spectra of all complexes are in good agreement with the coordination of a neutral tetradentate N₄ ligand to the cooper (II) through azomethinic and pyridinic nitrogen. Magnetic, EPR and electronic spectral studies show a monomeric distorted octahedral geometry for all Cu(II) complexes. Conductance measurements suggest the non-electrolytic nature of the compounds, except for copper (II) nitrate and perchlorate complexes which are 1:2 electrolytes. Heats of decomposition, ΔH, associated with the exothermal effects were also determined.     

Mono- and Bi-Nuclear Metal Complexes of Schiff-Base Hydrazone (ONN) Derived from o-Hydroxyacetophenone and 2-Amino-4-Hydrazino-6-Methyl Pyrimidine

A tridentate ONN donor Schiff-base hydrazone ligand, H₂L, was synthesized by the condensation of 2-amino-4-hydrazino-6-methyl pyrimidine with o-hydroxyacetophenone. The structure of the ligand was elucidated by IR and ¹H NMR spectra which indicated the presence of three different coordinating groups, the oxygen atom of the phenolic OH group, the nitrogen atom of the azomethine, C=N, group and one of the nitrogen atoms of the heterocyclic ring. The ligand behaves either as a tridentate (N₂O sites) neutral, mono- or di-basic ligand or as a bidentate (NO sites) monobasic ligand depending on the pH of the reaction medium and the metal ion. The mass spectrum of the ligand showed the presence of the molecular ion peak. Different types of metal complexes, mononuclear such as [(HL)M(OAc)]·xH₂O (M = Cu or Zn), [(HL)M(OAc)H₂O]·xH₂O (M = Ni or UO₂), [(HL)Co(OH₂)Cl]·2H₂O, [(H₂L)FeCl₃]·3½H₂O, [(L)FeCl(H₂O)₂]· 2¼H₂O, [(HL)L'FeCl(H₂O)]·H₂O (L' = 8-hydroxyquinoline, 8-HQ), [(HL)L'FeCl]Cl·xH₂O (L' = 1,10-phenanthroline, phen, or 2,2'-bipyridyl, bpy) and [(HL)L'Cu]·ClO₄ (L' = phen). Also, binuclear complexes with oxalic acid of the type [(HL)ClFe(ox)FeCl(HL)], [(HL)Cu(ox)Cu(HL)] were obtained. The IR spectra of the binuclear complexes indicated that the oxalate anion acts as a bridging tetradentate ligand. Elemental analyses, IR, electronic and ESR spectra as well as conductivity and magnetic susceptibility measurements were used to elucidate the structures of the newly prepared metal complexes. Square-planar geometry is suggested for the Cu(II) complex, octahedral geometry for the Fe(III), Ni(II) complexes, tetrahedral geometry for the Co(II) and Zn(II) complexes and pentagonal-bipyramidal geometry for the UO₂(VI) complex.     

Synthesis,characterization and antimicrobial studies of novel ONO donor hydrazone Schiff base complexes with some divalent metal (II) ions

Metal complexes of two general formulae [M(L)(Cl)(H₂O)₂] [M = Mn(II), Co(II), Ni(II) and Cu(II)] and [M(L)(H₂O)] [M = Zn(II) and Cd(II)] with pyrazine-2-carbohydrazone of 2-hydroxy-5-methylacetophenone (H₂L) are synthesized and characterized by microanalytical, thermal, magnetic susceptibility measurement, spectroscopic (IR, ¹H NMR, ¹³C NMR), mass, molar conductance, X-ray powder diffraction, ESR and SEM studies. While the molar conductance measurements in DMSO indicated their non-electrolytic nature, the spectroscopic studies confirmed a tridentate ONO donor behaviour of the ligand towards the central metal ion. Based on the physico-chemical studies monomeric octahedral geometry around Mn(II), Co(II), Ni(II) and Cu(II) ions (i.e. for the first series of complexes) whereas tetrahedral to Zn(II) and Cd(II) ions (i.e. for the second series of complexes) are suggested. Based on the thermal behavior of the complexes, various kinetic and thermodynamic parameters were evaluated using Coats-Redfern method. The ligand and its metal complexes were screened for in vitro antibacterial and antifungal activity against Gram +ve S. aureus, B. subtilis and Gram –ve E. coli and S. typhi. and fungal strains, C. albicans and A. niger. The observed data infer promising biological activity of some of these complexes compared the parent ligand against all bacterial and fungal species.     

Metal complexes of pyrimidine derived ligands – Syntheses,characterization and X-ray crystal structures of Ni(II), Co(III) and Fe(III) complexes of Schiff base ligands derived from S-methyl/S-benzyl dithiocarbazate and 2-S-methylmercapto-6-methylpyrimidine-4-carbaldehyde

Two new pyrimidine based NNS tridentate Schiff base ligands S-methyl-3-((2-S-methyl-6-methyl-4-pyrimidyl)methyl)dithiocarbazate [HL₁] and S-benzyl-3-((2-S-methyl-6-methyl-4-pyrimidyl)methyl)dithiocarbazate [HL₂] have been synthesised by the 1:1 condensation of 2-S-methylmercapto-6-methylpyrimidine-4-carbaldehyde and S-methyl/S-benzyl dithiocarbazate. A Ni(II) complex of HL₁ and Co(III) and Fe(III) complexes of HL₂ have been prepared and characterized by elemental analyses, molar conductivities, magnetic susceptibilities and spectroscopic studies. All the bis-chelate complexes have a distorted octahedral arrangement with an N₄S₂ chromophore around the central metal ion. Each ligand molecule binds the metal ion using the pyrimidyl and azomethine nitrogen and thiolato sulfur atoms (except in the nickel complex, one ligand molecule uses the thione sulfur in lieu of thiolato sulfur atom). In the Ni(II) complex, one of the ligand molecules behaves as a neutral tridentate and the other molecule functions as a uninegative tridentate, whereas in the Co(III) and Fe(III) complexes, the ligand molecules behave as monoanionic tridentate. All the complexes were analyzed by single crystal X-ray diffraction and significant differences concerning the distortion from an octahedral geometry of the coordination environment were observed.     

Synthesis,characterization and biological studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes with pyrral-l-histidinate

The Schiff base ligand, pyrral-l-histidinate(L) and its Co(II), Ni(II), Cu(II) and Zn(II) complexes were synthesized and characterized by elemental analysis, mass, molar conductance, IR, electronic, magnetic measurements, EPR, redox properties, thermal studies, XRD and SEM. Conductance measurements indicate that the above complexes are 1:1 electrolytes. IR data show that the ligand is tridentate and the binding sites are azomethine nitrogen, imidazole nitrogen and carboxylato oxygen atoms. Electronic spectral and magnetic measurements indicate tetrahedral geometry for Co(II) and octahedral geometry for Ni(II) and Cu(II) complexes, respectively. The observed anisotropic g values indicate the presence of Cu(II) in a tetragonally distorted octahedral environment. The redox properties of the ligand and its complexes have been investigated by cyclic voltammetry. Thermal decomposition profiles are consistent with the proposed formulations. The powder XRD and SEM studies show that all the complexes are nanocrystalline. The in vitro biological screening effects of the synthesized compounds were tested against the bacterial species, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa and Staphylococcus aureus; fungal species, Aspergillus niger, Aspergillus flavus and Candida albicans by the disc diffusion method. The results indicate that complexes exhibit more activity than the ligand. The nuclease activity of the ligand and its complexes were assayed on CT DNA using gel electrophoresis in the presence and absence of H₂O₂.     

Synthesis, spectroscopic, structural and electrochemical studies of nickel(II) and copper(II) complexes derived from 2-hydroxy-4-methacryloyloxybenzaldehyde

The free Schiff bases H₂MABCE, H₂MABCP, and H₂MABCT and their complexes [Ni(MABCE)], [Ni(MABCP)], [Ni(MABCT)], [Cu(MABCE)], [Cu(MABCP)], and [Cu(MABCT)] have been synthesized and characterized by spectroscopic, cyclic voltammetric, and thermal studies. The geometry around nickel is square planar with N₂O₂ donor atoms. Cyclic voltammetric studies of the Ni(II) complexes show one-electron quasi-reversible waves corresponding to Ni(II)/Ni(I) and Ni(II)/Ni(III) processes. The Cu(II) complexes exhibit an irreversible well defined one electron transfer reduction peak in the range of ?0.34 to ?1.08 V. The electronic spectra of the complexes suggest a four-coordinate geometry. The crystal structure of the ligand H₂MABCT and the complex [Ni(MABCP)] have also been reported. The mean Ni–N and Ni–O bond distances are Ni–N = 1.849(4) and Ni–O = 1.837(4) Å.     

Synthesis and characterization of the complexes of some transition metals with 2-acetyl pyridine (N-benzoyl) glycyl hydrazone

Complexes of Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) with 2-acetyl pyridine (N-benzoyl) glycyl hydrazone(2-ApBzGH) have been synthesized and characterized by elemental analyses, molar conductances, magnetic susceptibility, IR, electronic, ESR,¹H,¹³C and¹¹³Cd NMR spectral and X-ray diffraction studies. IR and NMR data suggest the tridentate nature of the ligand coordinating as a neutral species in the addition complexes and as a uninegative species in the deprotonated complexes. The presence of more than one isomer of the ligand has been established by¹H NMR spectra of the ligand and complexes recorded over the 298–396 K range. The X-ray powder diffraction patterns of [Cd(2-ApBzGH)Cl]Cl and [Cu(2-ApBzGH)Cl(H₂O)₂]Cl are indexed for orthorhombic and tetragonal crystal systems respectively.     

[2,6‐Bis(5‐methyl‐2‐pyridyl)phenyl‐κ3N,C1,N′]chloridoplatinum(II)

In the title compound, [Pt(C₁₈H₁₅N₂)Cl], the Pt^II centre adopts a distorted square‐planar coordination geometry due to the pincer‐type monoanionic N–C–N tridentate ligand. The planar complexes stack viaπ–π interactions to form two‐dimensional accumulated sheets. This packing pattern is in contrast to that in related pincer‐type N–C–N complexes, which exhibit a one‐dimensional columnar stacking.     

Synthesis,structural, spectroscopic,biological and catalytic activity of Co(II), Ni(II) and Cu(II) complexes of benzilic hydrazide (BH)

Co(II), Ni(II) and Cu(II) chloro complexes of benzilic hydrazide (BH) have been synthesized. Also, reaction of the ligand (BH) with several copper(II) salts, including NO₃ ^?, AcO^?, and SO₄ ^? afforded metal complexes of the general formula [CuLX(H₂O) _n ]·nH₂O, where X is the anion and n = 0, 1 or 2. The newly synthesized complexes were characterized by elemental analysis, mass spectra, molar conductance, UV–vis, IR spectra, magnetic moment, and thermal analysis (TG/DTG). The physico-chemical studies support that the ligand acts as monobasic bidentate towards metal ion through the carbonyl and hydroxyl oxygen atoms. The spectral data revealed that the geometrical structure of the complexes is square planar for Cu (II) complexes and tetrahedral for Co(II) and Ni(II) complexes. Structural parameters of the ligand and its complexes have been calculated. The ligand and its metal complexes are screened for their antimicrobial activity. The catalytic activities of the metal chelates have been studied towards the oxidative decolorization of AB25, IC and AB92 dyes using H₂O₂. The catalytic activity is strongly dependent on the type of the metal ion and the anion of Cu(II) complexes.