Nickel(II) and copper(II) complexes of Schiff base ligands containing N 4O 2 and N 4S 2 donors with pyrrole terminal binding groups: Synthesis, characterization, X-ray structures, DFT and electrochemical studies (original) (raw)
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Transition Metal Chemistry, 2017
The synthesis, structure, spectroscopic and electro-spectrochemical properties of salicylaldimine Schiffbase ligands (L n H) (n = 1, 2, and 3) (L 1 H = N-[2-amino-8-hydroxyquinoline]-salicylaldimine, L 2 H = N-[2amino-8-hydroxyquinoline]-5-bromosalicylaldimine and L 3 H = N-[2-amino-8-hydroxyquinoline]-5methoxysalicylaldimine), respectively, and their dinuclear copper(II) complexes [Cu 2 (L n) 2 ] are described. Three new dissymmetric tetradentate salicylaldimine ligands containing a donor set of NOOO were prepared by reaction of 2-amino-8-hydroxyquinoline with different salicylaldehydes. The dinuclear copper(II) metal complexes of these ligands were synthesized by treating an ethanolic solution of the appropriate ligand with an equimolar amount of Cu(Ac) 2 ÁH 2 O. The ligands and their copper complexes were characterized by FT-IR, UV-vis, 1 H NMR, elemental analysis, molar conductivity, mass spectra and thermal analysis methods in addition to magnetic susceptibility and spectroelectrochemical techniques. The reaction of these ligands in a 1:1 mole ratio with copper(II) acetate afforded dinuclear Cu(II) metal complexes. The room temperature magnetic moments of [Cu 2 (L n) 2 ] complexes are found between 1.12 and 1.28 BM for per Cu(II) molecule.
Polyhedron, 2016
A new unsymmetrical tridentate NNS Schiff base ligand, 2-(2-nitrophenylthio)-N-((pyridine-2-yl) methylene)benzenamine (L), and its Mn(II), Ni(II), Cu(II), and Zn(II) complexes were synthesized. These compounds were characterized by different physicochemical and spectroscopic techniques. The molecular structure of [NiL 2 ](ClO 4) 2 was determined by single-crystal X-ray diffraction. In this complex, two ligands coordinate through azomethine-N, pyridine-N, and thioether-S, forming a mononuclear 6-coordinate distorted octahedral geometry about a nickel.
2016
Synthesis, structure, and physico-chemical investigation of Ni (II) and Cu (II) complexes derived from Schiff base of 2-aminophenol with terephthaldehyde and then it allowed to react with metal salts with 8-hydroxyquinoline to form binuclear Schiff base mixed ligand metal complexes. All the synthesized ligand and complexes were characterized based on elemental analysis, 1 H NMR ,UV-Visible, molar conductance , FTIR, and thermal analysis (TGA/DTA). Molar conductance of the metal complexes shows that chelates are non electrolytic nature. An IR spectrum shows that the Schiff basses are coordinated with NO donar sites of azomethine nitrogen and phenolic oxygen and qunoline nitrogen and phenolic oxygen of 8-hydroxyquinoline group. Formation of Schiff base ligand was confirmed by 1 H NMR spectra. The electronic spectra show that Ni (II) and Cu (II) complexes have tetrahedral geometry. Thermal stability of complexes was also studied to assess the compatibility of the donating moieties. Sch...
Inorganica Chimica Acta, 2006
The 1:1 condensation of 2,4-pentanedione and 1,2-diaminopropane gives a mixture two positional isomers of tridentate mono-condensed product 7-amino-4-methyl-5-aza-3-octene-2-one (HAMAO) and 7-amino-4,6-dimethyl-5-aza-3-heptene-2-one (HADAH) that reacted readily with Ni(II) thiocyanate to yield exclusively a single product, [Ni(AMAO)NCS] (1) in which the methyl substituent of diamine is 'remote' from the imino nitrogen. The mixture of terdentate ligands has been used for further condensation with pyridine-2-carboxaldehyde or 2-acetylpyridine to obtain the unsymmetrical tetradentate Schiff base ligands. The tetradentate ligands formed by the condensation of it and pyridine-2-carboxaldehyde readily yielded complexes with Cu(II) and Ni(II) (2 and 3, respectively). Crystal structure analysis shows that in 2 the condensation site of the diamine with 2,4-pentanedione is the same as in 1 but that in 3 is different (the methyl group of the diamine is located in the vicinity of 2,4-pentanedione), i.e., the tetradentate ligand is in two different isomeric forms in complexes 2 and 3. Another tetradentate ligand, obtained by the condensation of the tridentate ligands and 2-acetylpyridine yielded a Ni(II) complex (4) where the methyl group is in the vicinity of 2,4-pentanedione as in 3. The isomerization in the Ni(II) complexes has been studied by NMR spectroscopy.
Polyhedron, 1989
Neutral copper(I1) complexes of Schiff bases derived from substituted salicylaldehydes and 2-aminopyridine methyl derivatives have been synthesized by an electrochemical procedure. The crystal and molecular structure of bis(N-[2-(3_methylpyridyl)]-5-methoxysalicylideneiminato}copper (II) and of bis{N-[2-(6-methylpyridyl)]-salicylide-neiminato}copper(II) have been determined by X-ray diffraction. The former compound crystallizes in the monoclinic space group C2/c with four molecules in the unit cell and cell constants a = 16.784(2), b = 16.344(2) and c = 11.21 l(2) A, and j? = 124.08(l)", while the other complex crystallizes in the monoclinic space group P2 ,/c with two molecules in a cell of dimensions a = 12.456(l), b = 7.812(2) and c = 12.047(2) A, and j? = 110.48(l)". In both structures, the metals adopt square-planar coordination geometries and the pyridyl nitrogen atoms are not coordinated. The electronic and IR spectra of the complexes are discussed and related to the structure.
Abstract - Three new mononuclear copper(II) complexes namely [Cu(L)(CH3COO)]X, (X = PF6 - (1) and BF4 - (2)), [Cu(L)(NCS)]PF6 (3) and one nickel(II) complex [Ni(L)Cl2 ] (4), where L = {N,N-bis(3,5-dimethylpyrazol-1-ylmethyl)}(2- aminomethyl)pyridine have been synthesized and characterized by several techniques including X-ray crystallography, microanalyses, IR, UV-Vis spectroscopy and mass spectrum analysis. Molecular structure of the complexes [Cu(L)(CH3COO)]PF6 .H2O and [Cu(L)(NCS)]PF6 have been solved by single crystal X-ray diffraction studies and showed that copper atom in both the complexes have distorted square pyramidal geometry. The proposed structure of nickel complex is octahedral.
Polyhedron, 2006
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Polyhedron, 2007
Two new pyrimidine based NNS tridentate Schiff base ligands S-methyl-3-((2-S-methyl-6-methyl-4-pyrimidyl)methyl)dithiocarbazate [HL 1 ] and S-benzyl-3-((2-S-methyl-6-methyl-4-pyrimidyl)methyl)dithiocarbazate [HL 2 ] 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 HL 1 and Co(III) and Fe(III) complexes of HL 2 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 N 4 S 2 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.