Mohamed Nazimuddin

The preparation, characterization, crystal structure and biological activities of some copper(II) complexes of the 2-benzoylpyridine Schiff bases of S-methyl- and S-benzyldithiocarbazate

The complexes [Cu(NNS)X] (HNNS represents the 2-benzoylpyridine Schiff bases of S-methyl- or S-benzyldithiocarbazate; XCl, Br, NO3) have been prepared and characterized by a variety of physico-chemical techniques. Magnetic and spectral evidence support a square-planar structure for the [Cu(BpSR)X] (BpSR=the benzoylpyridine Schiff bases; RCH3, CH2C6H5; XCl, Br) and [Cu(BpSMe)NO3] complexes and a five-coordinate distorted square-pyramidal structure for the [Cu(BpSBz)NO3] complex. The crystal structures of [Cu(BpSMe)NO3] and [Cu(BpSBz)NO3] have been determined by X-ray diffraction studies. The complex [Cu(BpSMe)NO3] crystallizes in the triclinic space group P1 with a=7.600(3), b=10.5346(2), c=11.564(3) A, α=116.0033(14), β=103.91(3), γ=91.55(3)°, V=798.3(4) A and Z=2. The complex has a distorted square-planar geometry with the copper ion lying in an approximate plane of four coordinating atoms, three of which come from the 2-benzoylpyridine Scniff base of S-methyldithiocarbazate while the fourth coordination site is occupied by an oxygen from the nitrate ligand. The complex, [Co(BpSBz)NO3] crystallizes in the monoclinic space group P21/a with a=9.0124(19), b=18.501(5), c=13.0642(24) A, β=106.377(15)°, V=2089(9) A3 and Z=4. The coordination environment around the copper(II) ion is a distorted square-pyramid with three donor atoms (NNS) coming from the 2-benzoylpyridine Schiff base and the fourth and fifth atoms (oxygen) coming from the bidentade NO3− ion. The antifugal and antibacterial properties of the Schiff bases and their copper(II) complexes have been evaluated against three pathogenic fungi and two bacteria. The Schiff bases and copper(II) complexes display moderate antifungal activities but their activities are less than that of the commercially important antifungal agent nystatin.

Synthesis, characterization, antifungal properties and X-ray crystal structures of five- and six-coordinate copper(II) complexes of the 6-methyl-2-formylpyridine4N-dimethylthiosemicarbazone ☆

Abstract Copper(II) complexes of formulas, [Cu(NNS)(NO3)(H2O)]·H2O and [Cu(NNS)2] (NNS=anionic form of the 6-methyl-2-formylpyridine4N-dimethylthiosemicarbazone) have been synthesized and characterized by a variety of physico-chemical techniques. Magnetic and spectroscopic data support a five-coordinate structure for the [Cu(NNS)(NO3)(H2O)]·H2O complex and a distorted octahedral structure for the [Cu(NNS)2] complex. The crystal structures of both complexes have also been determined by X-ray diffraction. The mono-ligated nitrato-complex has a five-coordinate geometry, with the thiosemicarbazone ligand coordinated to the copper(II) ion as a uninegatively charged NNS tridentate chelating agent via the pyridine nitrogen atom, the azomethine nitrogen atom and the thiolate sulfur atom. The fourth and fifth coordination positions around the copper(II) ion are occupied by the nitrato and aqua ligands, respectively. The bis-ligand copper(II) complex, [Cu(NNS)2] has a distorted octahedral structure with two uninegatively charged tridentate NNS thiosemicarbazone ligands coordinated to the copper(II) ion via the pyridine nitrogen atoms, the azomethine nitrogen atoms and the mercaptide sulfur atoms in a meridional arrangement. The ligand is fungitoxic against the phytopathogenic fungi, A. alternata, F.equiseti and M. phaseolina but the complexes are less active than the free ligand.

Synthesis, characterization and biological activities of some new nickel(II), copper(II), zinc(II) and cadmium(II) complexes of quadridentate SNNS ligands

SummaryThe quadridentate ligands, prepared by condensation ofS-methyl- andS-benzyldithiocarbazate with glyoxal, form stable crystalline complexes of gerferal formula, M(SNNS) (M=NiII, CuII, ZnII and CdII; SNNS−2=ligand dianion). The NiII complexes are diamagnetic but electronic spectral data support a dimeric five-coordinate geometry. Based on magnetic and spectral data, a five-coordinate square-pyramidal structure is also assigned to the copper(II) complexes. The ZnII and CdII complexes are polymeric and octahedral. The Schiff bases and metal complexes display good antifungal and antibacterial properties.

The synthesis, characterization and bioactivities of some copper(II) complexes of the 2-acetylpyridine schiff bases of s-methyl- and s-benzyldithiocarbazate, and the x-ray crystal structure of the nitrato(s-benzyl-β-n-(2-acetylpyridyl) methylenedithiocarbazato)copper(II) complex

Copper(II) complexes of the general formula [Cu(Ap-SMe)X] or [Cu(Ap-SBz)X] (where HAp-SMe and HAp-SBz, respectively, represent the 2-acetylpyridine Schiff bases of S-methyl- or S-benzyldithiocarbazate; XCl, Br, NO3) have been prepared and characterized by a variety of physico-chemical techniques. Magnetic and spectroscopic evidence support a square-planar structure for the [Cu(Ap-SMe)X] (XCl, Br) complexes and a five-coordinate structure for the [Cu(Ap-SBz)NO3] complex. The structure of [Cu(Ap-SBz)NO3] has been determined by X-ray diffraction studies. The geometry of the complex is a distorted square-pyramid with the NNS tridentate ligand and an oxygen atom of the nitrate ion occupying the basal plane. The fifth coordination position is occupied by another oxygen from the nitrate ion. The anti-fungal and anti-bacterial properties of the Schiff bases and their copper(II) complexes have been evaluated against the phytopathogenic fungi A. solanyi, F. equisetti and M. phaseolina and the pathogenic bacteria E. coli and S. aureas. The fungitoxicity of the five-coordinated [Cu(Ap-SBz)NO3] complex approaches that of nystatin, whereas the Schiff base HAp-SMe and its copper(II) complex [Cu(Ap-SMe)NO3] display significant antibacterial activity against E. coli and S. auereas.

The preparation and characterization of some copper(II) Complexes of the 6-methyl-2-formylpyridine thiosemicarbazone and the x-ray crystal structure of the chloro(6-methyl-2-formylpyridinethiosemicabazonato) copper(II) complex

Abstract Copper(II) complexes of general empirical formulae, [Cu(NNS)X] · xH 2 O (NNS = uninegatively charged tridentate ligand formed by condensation of 6-methylpyridine-2-aldehyde with thiosemicarbazide ; X = Cl, Br, NO 3 , and CH 3 COO; x= 0, 1) and [Cu(NNS) 2 ] · 0.5H 2 O have been prepared and characterized by conductance, magnetic, electronic and infrared spectroscopic measurements. Magnetic and spectral data support a square-planar structure for [Cu(NNS)X] (X = Cl, Br, NO 3 , CH 3 COO) and a distorted octahedral structure for [Cu(NNS) 2 ] · 0.5H 2 O. The crystal and molecular structure of [Cu(NSS)Cl] has been determined by X-ray diffraction. This complex has a distorted square-planar geometry with the copper(II) ion lying in an approximate plane of four coordinating atoms, three of which come from the 6-methylpyridine-2-carboxaldehyde thiosemicarbazone and the fourth coordination site is occupied by the chloride ligand. The thiosemicarbazone is present as the thiolate form and is coordinated to the copper(II) ion via the pyridine nitrogen atom, the azomethine nitrogen atom and the mercaptide sulfur atom. Copyright

The preparation and characterization of mono- and bis-chelated cadmium(II) complexes of the di-2-pyridylketone Schiff base of S-methyldithiocarbazate (Hdpksme) and the X-ray crystal structure of the [Cd(dpksme)2] · 0.5 MeOH complex

New cadmium(II) complexes of empirical formulae, [Cd(dpksme)X] (dpksme = anionic form of the Schiff base; X = NCS−, Cl−, I−) and [Cd(dpksme)2] · 0.5MeOH, respectively have been prepared and characterized. The mono-ligated cadmium(II) complexes, [Cd(dpksme)X] are four-coordinate and tetrahedral but the bis-ligand complex, [Cd(dpksme)2] · 0.5MeOH is six-coordinate and octahedral. The crystal and molecular structure of [Cd(dpksme)2] · 0.5MeOH has been determined by X-ray diffraction. The complex has a distorted mer-octahedral structure in which the ligands are coordinated as uninegatively charged tridentate chelating agents via the pyridine nitrogen atoms, the azomethine nitrogen atoms and the thiolate sulfur atoms. The distortion from regular octahedral geometry is ascribed to the restricted bite angles of the ligands. The Schiff base and its cadmium(II) complexes exhibit mild antibacterial activities against Shigella dysenteriae, Bacillus cereus, Staphylococcus aureus and Escherichia coli. They are also mildly fungitoxic against the phytopathogenic fungi, Alternaria alternata and Macrophomina phaseolina.

Mono- and bis-chelated nickel(II) complexes of the di-2-pyridylketone Schiff base of S-methyldithiocarbazate and the X-ray crystal structure of the bis[S-methyl-β-N-(di-2-pyridyl)-methylenedithiocarbazato]nickel(II) complex

Abstract The di-2-pyridylketone Schiff base of S-methyldithiocarbazate (Hdpksme) reacts with nickel(II) salts giving both mono- and bis-chelated complexes of empirical formulae, [Ni(dpksme)X] (dpksme=anioninc form of the Schiff base; X=NCS−, Cl−) and [Ni(dpksme)2], respectively. These compounds have been characterized by magnetic and spectroscopic techniques. The mono-ligated nickel(II) complexes are four-coordinate and square-planar but the bis-ligand complex is six-coordinate and octahedral. The crystal and molecular structure of [Ni(dpksme)2] has been determined by X-ray crystallography. The complex has a distorted mer-octahedral structure in which the ligands are coordinated as uninegatively charged tridentate chelating agents via the pyridine nitrogen atoms, the azomethine nitrogen atoms and the thiolate sulfur atoms. The distortion from regular octahedral geometry is ascribed to the restricted bite angles of the ligands. The ligand and its nickel(II) complexes exhibit weak antimicrobial activity against the pathogenic bacteria, S. dysenteriae, B. cercus, S. aureus and E. coli and the fungi, A. alternata and M. phaseolina.

Preparation, characterization and antifungal properties of nickel(II) complexes of tridentate ONS ligands derived from N-methyl-S-methyldithiocarbazate and the X-ray crystal structure of the [Ni(ONMeS)CN]·H2O complex

Nickel(II) complexes of general empirical formula, NiLX·nH2O (L = deprotonated form of the Schiff base formed by condensation of N-methyl-S-methyldithiocarbazate with 2-hydroxybenzaldehyde or 5-bromo-2-hydroxybenzaldehyde; X = Cl−, Br−, NCS−, AcO− or CN−; n = 0, 1) have been prepared and characterized by a variety of physico-chemical techniques. Magnetic and spectroscopic data support a square-planar structure for these complexes. The crystal structure of the [Ni(ONMeS)CN]·H2O complex (ONMeS = anionic form of the 2-hydroxybenzaldehyde Schiff base of N-methyl-S-methyldithiocarbazate) has been determined by X-ray diffraction. The complex has a distorted square-planar structure in which the Schiff base is coordinated to the nickel(II) ion as a uninegatively charged anion coordinating via the phenolic oxygen atom, the azomethine nitrogen atom and the thione sulfur atom. The fourth coordination position is occupied by a cayano ligand. The antifungal properties of the Schiff bases and their nickel(II) complexes were studied against three plant pathogenic fungi. The ligands display moderate fungitoxicities against these organisms but their nickel(II) complexes are less active than the free ligands.

Synthesis, characterization and biological activities of some nickel(II) complexes of tridentate NNS ligands formed by condensation of 2-acetyl- and 2-benzoylpyridines with S-alkyldithiocarbazates

SummaryNickel(II) complexes of four tridentate NNS Schiff base ligands, derived by condensing 2-acetyl-and 2-benzoylpyridine with S-methyl- and S-benzoyldithiocarbazate, have been prepared and characterized. The monoligated complexes, [Ni(NNS)X] (NNS = anionic ligand; X = Cl, Br, NCS, I) are diamagnetic and square-planar, whereas the bis-ligand complexes, [Ni(NNS)2] are paramagnetic and tetragonal. The Schiff bases are fungitoxic towards A. solani, F. equisetti and M. phaseolina (approaching the toxicity of the commercial fungicide Nystatin), but the nickel(II) complexes are less fungitoxic than the free ligands.

Synthesis and characterization of some metal complexes containing a quadridentate NSSN and a sexidentate ONSSNO ligand

Abstract New metal complexes of general formulae M(NSSN)X2 · xH2O (M = Ni, Cu; NSSN = quadridentate sulphur-nitrogen ligand; X = Cl, Br, NCS or I; x = 0 or 2) and M(ONSSNO) [M = Ni, Cu, Zn, Cd; ONSSNO2− = anion of sexidentate ligand formed from salicylaldehyde and α,α′-xylene-bis(N-methyldithiocarbazate)] have been prepared and characterized by conductance, magnetic and spectroscopic measurements. The nickel(II) complexes of both the ligands are high-spin and octahedral. Tetragonally distorted octahedral structures are assigned to the copper(II) complexes. In the presence of the sexidentate ligand, cobalt(II) is readily air-oxidized to form a cobalt(III) complex, Co(ONSSNO)Cl, which is spin-paired and octahedral.