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.     

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

Mononuclear nickel(II) complexes with 2-aminoacetophenone thiosemicarbazones and three N(4)-substituted thiosemicarbazones have been prepared in EtOH solution and characterized by physical and spectral methods. I.r. and electronic spectra of the thiosemicarbazones and their complexes, along with physical properties of the complexes, have been obtained. The 2-aminoacetophenone thiosemicarbazones coordinate both as neutral and anionic ligands via the thiosemicarbazone moiety's azomethine nitrogen and thione/thiolato sulfur [on loss of the N(2) hydrogen].     

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.     

Cobalt(III) complexes of formyl- and acetylpyrazine N(4)-substituted thiosemicarbazones

Cobalt(III) complexes of acetyl- and formylpyrazine N(4)-substituted thiosemicarbazones have been synthesized and characterized by spectral and physical techniques. The crystal structure of the bis{formylpyrazine N(4)-methylthiosemicarbazone}cobalt(III) complex shows the two ligands coordinated in a mer-configuration, and the orientation of the thiosemicarbazone moiety's N(4)-methyl is Z with respect to the thiolato sulfur in both ligands. Included is the crystal structure of the bis- {2-acetylpyridineN(4)-propylthiosemicarbazone}cobalt(III) complex in which the two thiosemicarbazone ligands are also in the mer-configuration, but one ligand has the propyl group oriented Z with respect to the thiolato sulfur and the other E. Both complexes' bond lengths and bond angles are compared with other cobalt(III) thiosemicarbazone complexes.     

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.     

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 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 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.     

Spectral characterization of iron(III) complexes of 2-benzoylpyridine N(4)-substituted thiosemicarbazones

Three iron(III) complexes (1-3) of 2-benzoylpyridine N(4)-phenyl thiosemicarbazone (HL1) and one iron(III) complex (4) of 2-benzoylpyridine N(4)-cyclohexyl thiosemicarbazone (HL2) were synthesized and characterized by means of different physicochemical techniques viz., molar conductivity measurements, magnetic susceptibility studies and electronic, infrared and EPR spectral studies. The analytical data and the molar conductance measurements of the complexes reveal that two molecules of the ligand and the anion are coordinated to the metal atom in all the four complexes. The magnetic moments of the complexes suggest that they are of low spin. From the infrared spectra of the ligands and the complexes it is confirmed that the ligands coordinate to iron(III) as an anion coordinating via the azomethine nitrogen, pyridyl nitrogen, and the thiolate sulphur. The EPR spectra of the complexes in the polycrystalline state at 298 and 110 K and in DMF solution at 110 K were recorded and all the spectra show three g values indicating that these complexes have rhombic distortion. All the iron(III) complexes in DMF solution at 110 K have similar anisotropic spectra with almost the same gav values, indicating that the bonding in all the complexes is similar and is unaffected by the coordination of the anion.     

Binuclear copper(II) complexes of 5-nitrosalicylaldehyde N(3)-substituted thiosemicarbazones

Summary Binuclear copper(II) complexes with six 5-nitrosalicylaldehyde N(3)-substituted thiosemicarbazones have been prepared and characterized. 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 crystal structure of a monomeric copper(II) complex of 5-nitrosalicylaldehyde piperidyl-thiosemicarbazone, H₂5NO₂Sapip, grown from DMF solution, has been solved. Neither the thiosemicarbazones or their binuclear copper(II) complexes show growth inhibitory activity against Aspergillus niger, but the copper(II) complexes show some activity against the fungus Paecilomyces variotii.     

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.     

Cobalt(II), nickel(II) and copper(II) with 2-substituted benzimidazole complexes

Summary Complexes of stoichiometries M(Acbim)₂X₂·nH₂O and M(Bzbim)₂X₂·nH₂O (M = Co, Ni or Cu; Acbim = 2-acetylbenzimidazole, Bzbim = 2-benzoylbenzimidazole; X = Cl, Br, NO₃ or ClO₄; n = 0, 1 or 2) have been prepared and characterised by spectroscopic and physicochemical methods. The ligands coordinate through carbonyl oxygen and tertiary nitrogen.     

2,6-Diacetyl- and 2,6-diformylpyridine bis(N4-substituted thiosemicarbazones) and their copper(II) and nickel(II) complexes

2,6-Diformylpyridine bis(N4-methylthiosemicarbazone) and bis(N4-dimethylthiosemicarbazone), H₂2,6Fo4M and H₂2,6Fo4DM, respectively, and 2,6-diacetylpyridine bis(N4-methylthiosemicarbazone) and bis(N4-dimethylthiosemicarbazone), H₂2,6Ac4M and H₂2,6Ac4DM, and their copper(II) and nickel(II) complexes have been synthesized. The ¹H-n.m.r. spectra of the free bis(thiosemicarbazones) show that, most often, one of the thiosemicarbazone moieties is hydrogen bonded to the pyridine nitrogen, and in [²H₆]-DMSO there is interaction with solvent oxygen. Golden yellow H₂2,6Ac4DM has a bifurcated hydrogen bonding interaction by one of the thiosemicarbazone moieties resulting in conjugation. Coordination to copper(II) and nickel(II) centers is via the pyridine nitrogen, amine nitrogen and thiolato sulfur and most of the complexes formed are polynuclear with thiosemicarbazone moieties from the same ligand coordinating to different metal centers.     

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.     

Cobalt(II) and iron(III) complexes with 2-substituted benzimidazole derivatives

Summary FeCl₃ and the primary amines 2-aminobenzimidazole (abi) and 2(2-aminophenyl)benzimidazole (apbi) give complexes for which spectroscopic and magnetic data suggest a pentacoordinate [FeCl₄].The reactions of complexes of primary amines of CoCl₂ and FeCl₃ with the carbonyl compounds acetylacetone (Hacac) and pyridylcarbaldehyde (pyc) yield complexes which contain the Schiff bases from the condensation of the amines and the carbonyl groups.Analytical data indicate formulae [CoCl₂(abiacac)₂], [CoCl₂(abipyc)], [FeCl₃(abiacac)], [FeCl₃(abipyc)₂] and [FeCl₃(apbipyc)] for the complexes. The cobalt(II) complexes are pseudo-tetrahedral, while the iron complexes are tetra-, penta-, or hexa-coordinate, as deduced from spectroscopic and magnetic measurements.     

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) 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.     

4-substituted but-2-enylpalladium(II) complexes

The chloro bridges in di-μ-chloro-4-methoxy- and di-μ-chloro-4-acetoxy-2-methyl-but-2-enylchloropalladium are split by Group V donor ligands Ph₃E (where E = P, As and Sb) to give [(η)³-H₂CC(CH₃)CHCH₂X) PdCl · EPh₃], (where X = OCH₃, OCOCH₃). These complexes are readily decomposed by dilute ethanolic hydrogen chloride yielding [Ph₃E · PdCl]₂ and isoprene. The structures of the compounds are discussed in the light of their ¹H NMR spectra.     

Structural and spectral studies of copper(II) and nickel(II) complexes of pyruvaldehyde mixed bis{N(4)-substituted thiosemicarbazones}

Pyruvaldehyde mixed bis(thiosemicarbazones) have been prepared in which the two thiosemicarbazone moieties have different N(4)-substituents. The mixed bis(thiosemicarbazones) and their copper(II) and nickel(II) complexes have been characterized with IR, electronic, mass, ¹H NMR (Ni) and EPR (Cu) spectra. Representative crystal structures have been solved of nickel(II) complexes with either a pyruvaldehyde mixed bis(thiosemicarbazone) or a bis(thiosemicarbazone) with identical N(4)-substituents acting as a tetradentate ligand. [Ni(Pu4M4DE)] has an N(4)-methylthiosemicarbazone substituent on the keto “arm” and N(4)-diethylthiosemicarbazone substituent on the aldehyde arm. [Ni(Pu4M)] contains two N(4)-methylthiosemicarbazone moieties. Both bis(thiosemicarbazones) form square-planar N₂S₂ complexes with nickel(II) and copper(II).