Copper(II) complexes of 4-acetamidobenzaldehyde N(4)-substituted thiosemicarbazones

Mononuclear and binuclear copper(II) complexes with four 4-acetamidobenzaldehyde N(4)-substituted thiosemicarbazones have been prepared in EtOH solution and characterized by physical and spectral methods. I.r., electronic, and e.s.r. spectra of the complexes, as well as i.r., electronic, and n.m.r. spectra of the thiosemicarbazones, have been obtained. These thiosemicarbazones coordinate as anionic or neutral ligands via the thiosemicarbazone moiety's imine nitrogen and thiolate/thione sulfur, the former on loss of the hydrazido hydrogen, N(2)H.     

Synthesis,magnetic and spectral studies of nickel(II) and zinc(II) complexes of 4-formylantipyrine N(4)-substituted thiosemicarbazones

The synthesis and characterization of nickel(II) and zinc-(II) complexes with 4-formylantipyrine N(4)-methyl-, N(4)-dimethyl- and 3-piperidylthiosemicarbazones are reported. Elemental analyses, molar conductivities, magnetic measurements and spectral (i.r., electronic and n.m.r.) studies have been used to characterize the complexes. The i.r. spectra show that the thiosemicarbazones behave as bidentate or tridentate ligands, either in the thione or thiolato form. Stereochemistries are proposed for the complexes on the basis of spectral and magnetic studies.     

Copper(II) complexes of 2-pyridineformamide N(4)-methylthiosemicarbazone

Reduction of 2-cyanopyridine by sodium in dry MeOH in the presence of N(4)-methylthiosemicarbazide produces 2-pyridineformamide N(4)-methylthiosemicarbazone, HAm4M. Copper(II) complexes have been prepared and characterized by molar conductivities, magnetic susceptibilities and spectroscopic techniques. Coordination is via the pyridyl nitrogen, imine nitrogen and thione or thiolato sulfur, when coordinating as the neutral or anionic ligand, respectively.     

Copper(II) complexes of formylpyrazine N(4)-substituted thiosemicarbazones

Copper(II) complexes of formylpyrazine N(4)-substituted thiosemicarbazones coordinated either as neutral or monoanionic ligands, [M(HL)X2] and [M(L)X], respectively, have been prepared and characterized. I.r., electronic and e.s.r spectra of the complexes, as well as 1H-n.m.r. spectra of the thiosemicarbazones, have been obtained. The N(4)-dialkyl and azacyclothiosemicarbazones and their copper(II) complexes show significant growth inhibitory activity against both Aspergillus niger and Paecilomyces variotii.     

Copper(II) complexes of 2-aminoacetophenone N(4)-substituted thiosemicarbazones

Mononuclear copper(II) complexes with 2-aminoacetophenone thiosemicarbazone and three N(4)-substituted thiosemicarbazones have been prepared in ethanolic solution and characterized by physical and spectral methods. I.r., electronic and e.s.r. spectra of the complexes, as well as i.r., electronic, and ¹H- and ¹³C-n.m.r. spectra of the thiosemicarbazones, have been obtained. The 2-aminoacetophenone thiosemicarbazones coordinate as neutral ligands via the thiosemicarbazone moiety's azomethine nitrogen and thione sulfur, except for the piperidylthiosemicarbazone, which undergoes deprotonation and coordinates via the thiolato sulfur, as well as through the azomethine nitrogen. Complexes formed in the presence of triethylamine also form complexes with the anionic form of these thiosemicarbazones.     

Copper(II) complexes with N,N-dimethylbiguanide

The N,N-dimethylbiguanide (HDMBG) complexes [Cu₂(HDMBG)₂Cl₄] (1) and respectively [Cu(HDMBG)₂]Cl₂·2H₂O (2) exhibit in vitro antimicrobial activity. The complexes were characterised by IR, electronic as well as EPR spectra. The IR spectra of complexes show the pattern of N,N-dimethylbiguanide coordinated as chelate. The electronic and EPR data are in agreement with a square pyramidal stereochemistry for (1) and a square planar one for (2). The in vitro qualitative and quantitative antimicrobial activity assays showed that the complexes exhibited variable antimicrobial activity against Gram-negative strains (Escherichia coli, Klebsiella spp. and Enterobacter sp.) isolated from the hospital environment. The thermal analysis has evidenced the thermal intervals of stability and also the thermodynamic effects that accompany them. The thermal behaviour in nitrogen is complex according to TG and DTA curves including melting, dehydration as well as compounds decomposition.     

Synthesis,magnetic and spectral studies of iron(III) and cobalt(II,III) complexes of 4-formylantipyrine N(4)-substituted thiosemicarbazones

The synthesis and characterization of complexes of iron(III), cobalt(II) and cobalt(III) with 4-formylantipyrine N(4)-methyl-, N(4)-dimethyl-, and 3-piperidylthiosemicarbazones are reported. Elemental analyses, molar conductivities, magnetic measurements and spectral (i.r., electronic and e.s.r.) studies have been used to elucidate the nature of the metal complexes. The i.r. spectra show that the thiosemicarbazones behave as bidentate or tridentate ligands, either in the thione or thiolato form. Different stereochemistries are proposed for the various cobalt(II) complexes on the basis of spectral and magnetic studies. This revised version was published online in June 2006 with corrections to the Cover Date.     

Copper(II) complexes of 6-methyl-2-acetylpyridine N(4)-substituted thiosemicarbazones

Summary Copper(II) complexes of 6-methyl-2-acetylpyridine N(4)-substituted thiosemicarbazones, coordinated either as a neutral or a monoanionic ligand, have been prepared and characterized. I.r., electronic and e.p.r. spectra of the complexes, as well as¹H- and¹³C-n.m.r. spectra of the thiosemicarbazones, have been recorded. Both the thiosemicarbazones and their copper(II) complexes show either modest or no growth inhibitory activity againstAspergillus niger, but theN(4)-dialkyl- and 3-azacyclo-derivatives, and particularly their copper(II) complexes, have considerable activity againstPaecilomyces variotii.     

Copper(II) complexes of 2-formyl-,2-acetyl- and 2-benzoylpyridine N(4)-o-, N(4)-m-, N(4)-p-chlorophenylthiosemicarbazones

Summary Cu^II complexes of 2-formyl, 2-acetyl- and 2-benzoylpyridine N(4)-o-, N(4)-m- and N(4)-p-chlorophenylthiosemicarbazones, coordinated either as a neutral or monoanionic ligand, have been prepared and characterized. I.r., electronic and e.s.r. spectra of the complexes, as well as ¹H- and ¹³C-n.m.r. spectra of the thiosemicarbazones, have been obtained. Both the thiosemicarbazones and their Cu^II complexes show either modest or no growth inhibitory activity against Paecilomyces variotii. Some of the thiosemicarbazones demonstrated significant activity against tumour cell strains.     

Copper(II) complexes of 2-formyl-, 2-acetyl- and 2-benzoyl-pyridine N(4)-phenyl-, N(4)-o-methoxyphenyl-, N(4)-p-methoxy-phenyl- and N(4)-p-nitrophenylthiosemicarbazones

Summary Cu^II complexes of 2-formyl-, 2-acetyl- and 2-benzoylpyridine N(4)-phenyl-, N(4)-o-methoxyphenyl-, N(4)-p-methoxyphenyl- and N(4)-p-nitrophenyltniosemicarbazones, coordinated either as neutral or monoanionic ligands, have been prepared and characterized. I.r., electronic and e.p.r. spectra of the complexes, as well as ¹H-and ¹³C-n.m.r. spectra of the thiosemicarbazones, have been obtained. Both the thiosemicarbazones and their complexes show either modest or no growth inhibitory activity against Paecilomyces variotii. However, some of these thiosemicarbazones possess significant activity against a number of tumour cell strains.     

Copper (II) complexes of N4,N4-disubstituted thio- and selenosemicarbazones of 2-acetylpyridine: ESR studies

Copper(II) complexes of 3-azabicyclo[3.2.2]nonane-3-thiocarboxylic acid 2-[1-(pyridinyl)ethylidene]hydrazide, and its selenium analog, 3-azabicyclo[3.2.2]nonane-3-selenocarboxylic acid 2-[1-(2-pyridinyl)ethylidene]hydrazide, were studied by ESR spectrometry in chloroform solution at room temperature and at liquid nitrogen temperature. ESR spectra were also observed for the complexes as magnetically doped samples in the corresponding Ni(II) lattices at room temperature. Nitrogen superhyperfine splitting is observed at room temperature in all the spectra. Splitting patterns indicate the non-equivalent nature of the two coordinating nitrogen atoms. The covalency parameter for the metal—ligand bond was determined for selected complexes. An order of ligand field strength has been proposed based on the magnitude of the g_| component of g observed in the polycrystalline state.     

Copper(II) complexes of N,N-dimethyl-2-picolinamine N-oxide

Cu(II) complexes have been prepared with N,N-dimethyl-2-picolinamine N-oxide (DMA) employing the tetrafluoroborate, nitrate, chloride and bromide salts. Complexes having 1:2 and 1:1 metal ion to ligand ratios have been isolated. Characterization has been accomplished by IR, electronic and ESR spectral measurements of the solid state. Significant changes occurred when spectral measurements of acetonitrile solutions of the various solids were attempted indicating alteration of the Cu(II) bonding occurs. Thermal data on the solids are included.     

Cobalt(II) complexes of 4-acetamidobenzaldehyde N(4)-substituted thiosemicarbazones

Cobalt(II) complexes of five 4-acetamidobenzaldehyde N(4)-substituted thiosemicarbazones have been prepared in EtOH solution and characterized by i.r., electronic and n.m.r. spectra, and by magnetic susceptibilities and molar conductivity measurements. The thiosemicarbazones coordinate as monoanionic or neutral ligands via the thiosemicarbazone azomethine nitrogen and thione/thiolato sulfur, the latter by loss of the thioamide hydrogen, N(2)H. The resulting cobalt(II) complexes exhibit a varied stereochemistry.     

Nickel(II) complexes of 4-acetamidobenzaldehyde N(4)-substituted thiosemicarbazones

Nickel(II) complexes with five 4-acetamidobenzaldehyde N(4)- substituted thiosemicarbazones have been prepared in EtOH solution and characterized by physical and spectral methods. N.m.r., i.r. and electronic spectra of the thiosemicarbazones and their complexes, along with physical properties of the complexes, have been recorded. These thiosemicarbazones coordinate as anionic ligands via the thiosemicarbazone moiety's azomethine nitrogen and thiolate sulfur [upon loss of the N(2) hydrogen] when reacted with NiCl2 in the presence of Et3N or with Ni(OAc)2.     

Copper(II) complexes with aroylhydrazones

The coordination chemistry of copper(II) with tridentate aroylhydrazones is briefly discussed in this article. Two types of aroylhydrazones derived from aroylhydrazines and ortho-hydroxy aldehydes or 2-pyridine-carboxaldehyde have been used. The characterization of the complexes has been performed with the help of various physico-chemical techniques. Solid state structural patterns have been established by X-ray crystallography. In the solid state, structural varieties of these complexes are seen to range from monomeric, dimeric, polymeric and one-dimensional self-assembly via hydrogen bonds and π-π interactions. EPR spectroscopy and variable temperature magnetic susceptibility measurements have been used to reveal the nature of the coordination geometry and magnetic characteristics of these complexes.     

Copper(II) and nickel(II) complexes of pyruvaldehyde bis{N(3)-substituted thiosemicarbazones}

Copper(II) and nickel(II) complexes of pyruvaldehyde bis{N(3)-methyl-, bis{N(3)-ethyl-, bis{N(3)-dimethyl- and bis{piperidylthiosemicarbazone} have been prepared and studied spectroscopically. The four thiosemicarbazones have been characterized by their melting points, as well as i.r., electronic and n.m.r. (1H,13C) spectra. The four coordinate copper(II) complexes have been studied by e.s.r. spectroscopy, and the copper(II) and nickel(II) complexes by several of the spectroscopic techniques mentioned above. Upon formation of these complexes, loss of protons from each thiosemicarbazone moiety occurs, and the bis(thiosemicarbazones) coordinate to the metal centres as dianionic, tetradentate N2S2 ligands.     

Ruthenium(II) 2-hydroxybenzophenone N(4)-substituted thiosemicarbazone complexes

New ruthenium(II) complexes with 2-hydroxybenzophenone N(4)-substituted (Me, Ph and/or piperidyl) thiosemicarbazones have been prepared and characterised by elemental analysis, molar conductivity, thermal analysis, spectroscopy (i.r., ¹H-n.m.r. and u.v.–vis.) and by cyclic voltammetry. The thiosemicarbazones coordinate to ruthenium(II) as mononegative tridentate ligands via the deprotonated hydroxyl group, N¹ nitrogen and thione sulphur centres. The redox properties, nature of the electrode processes and the stability of the complexes towards oxidation in CH₂Cl₂ are discussed. The change in the E _1/2 values of the complexes can be related to the basicity of the N(4)-substituents. All the complexes display an irreversible one-electron charge-transfer couple in the potential range studied. This revised version was published online in June 2006 with corrections to the Cover Date.     

Copper(II) and nickel(II) complexes of glyoxaldehyde bis{N(3)-substituted thiosemicarbazones}

Copper(II) and nickel(II) complexes of glyoxaldehyde bis{N(3)-methyl-, bis{N(3)-ethyl-, bis{N(3)-dimethyl-, bis{piperidyl- and bis{hexamethyleneiminylthiosemicarbazone} have been prepared and studied spectroscopically. The five bis(thiosemicarbazones) have been characterized by their melting points, as well as i.r., electronic and 1H-n.m.r. spectra. The four-coordinate copper(II) complexes have been studied by e.s.r. spectroscopy, and the copper(II) and nickel(II) complexes by a number of the spectroscopic techniques mentioned above. Upon formation of these complexes, loss of protons from each thiosemicarbazone moiety occurs, and the bis(thiosemicarbazones) coordinate to the metal centres as dianionic, tetradentate N2S2 ligands. This revised version was published online in June 2006 with corrections to the Cover Date.     

Copper(II) complexes of pyrrolidine dithiocarbamate

Copper(II)-pyrrolidine dithiocarbamate (PDTC) complexes having the general formula, [Cu(PDTC)₂], [Cu(PDTC)X₂]⁻ (where X = Cl⁻, I⁻, CN⁻, SCN⁻) and [Cu(PDTC)(en)]⁺ (en = ethylenediamine) have been prepared and characterized by IR spectroscopy and by thermogravimetric analysis (TGA and DTA). The IR data suggests that coordination of pyrrolidine dithiocarbamate (PDTC) takes place through the two sulphur atoms in a symmetrical bidentate fashion. The results of thermal analysis are consistent with the proposed composition of the complexes.