Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridineN-oxide. Part III. Spectral and thermal studies of the metal complexes of 2-acetylpyridineN-oxide thiosemicarbazone

Summary Metal complexes of 2-acetylpyridineN-oxide thiosemicarbazone have been prepared and characterized. Coordination occurs as a neutral bidentate (ON) and a deprotonated tridentate (ONS) ligand.     

Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridineN-oxide. II. The4 N-dimethyl derivative

Summary Metal ion complexes of 2-acetylpyridineN-oxide⁴ N-dimethylthiosemicarbazone (HLO4DM), have been prepared and spectroscopically characterised. The presence of two alkyl groups at⁴ N facilitates loss of the hydrogen from² N since HLO4DM is found as the anionic ligand in the majority of its complexes. The anionic LO4DM bonds to the metal ions via theN-oxide oxygen, the azomethine nitrogen, and the thiol sulphur atoms. The infrared, electronic, and electron spin resonance spectra of these complexes are compared to 2-acetylpyridineN-oxide⁴ N-methylthiosemicarbazone as well as 2-acetylpyridine⁴ N-dimethylthiosemicarbazone.     

Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridineN-oxide. I. The 4-methyl derivative

Summary TheN-methyl-2-[1-(2-pyridinyl-1-oxide)ethylidene]hydrazinecarbothioamide, HLO4M, has been used to prepare a series of Co^III, Ni^II and Cu^II complexes. Species with two deprotonated LO4M ligands, one LO4M and one HLO4M ligand, two HLO4M ligands and one HLO4M ligand with two small anionic ligands have been isolated. The deprotonated LO4M bonds as a tridentate ligandvia theN-oxide oxygen, the imine nitrogen (N¹ and the sulphur while the HLO4M ligand coordinates primarily as a bidentate ligandvia only the first two atoms listed above. I.r., electronic, mass and e.s.r. spectra have been used to determine the nature of these complexes. One of the more striking differences between these compounds and those prepared with other thiosemicarbazones of 2-acetylpyridine and 2-acetylpyridineN-oxide is that tetrahedral yellow [Ni(HL)X₂] rather than planar brown [NiLX] (X=Cl or Br) solids have been isolated with this ligand. Other differences in the nature of the coordination spheres of the various metal ions occur with this particular ligand when compared to previously studied thiosemicarbazone complexes.NATO Fellow, on leave from Medical Faculty, Istanbul University.     

Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridine. Part 2. The4 N-dimethyl derivative

Summary Metal ion complexes of the thiosemicarbazone,N-dimethyl-2-[1-(2-pyridinyl)ethylidene]hydrazinecarbothioamide (HL4DM) have been prepared and characterized spectrally. HL4DM coordinates primarily as the deprotonated tridentate ligand (i.e., pyrïdylN, azomethineN, and thione sulphur). In contrast to related thiosemicarbazones, oxidation to cobalt(III) does not occur during complex formation with cobalt(II) halides. Oxidation does occur on reflux with ethanolic Co(BF₄)₂, but we isolated a planar cobalt(II) complex as well. Only with the tetrafluoroborate salts of cobalt(II) and nickel(II) are complexes isolated containing the neutral thiosemicarbazone. Square planar [Ni(L4DM)X]complexes where X=Cl, Br, and OH have been isolated and e.s.r. spectra of a 1% Cu/Ni complex are compared to the results of other workers.     

Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridine. Part 4. The 3-piperidinyl derivative

Summary Metal ion complexes of the thiosemicarbazone, 3-piperidinyl-3-thiocarboxylic acid-2-[1-(2-pyridyl)ethylidene]hydrazide (HLpip) have been prepared and spectrally characterized. HLpip coordinates both as the deprotonated ligand (i.e., pyridylN, azomethineN, and thione sulphur) and the neutral ligand (i.e., pyridylN and azomethineN) with the sulphur possibly weakly coordinating in [Ni(HLpip)₂](BF₄)₂. All three preparative cobalt(II) salts yielded cobalt(III) cationic complexes. The nickel(II) and copper(II) chloride salts gave [M(Lpip)Cl] solids while complexes involving the neutral ligand were prepared with the corresponding bromide salts. Significant differences in the spectral properties of the various complexes are observed when compared to other thiosemicarbazones prepared from 2-acetylpyridine.     

Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridine. Part 1. The4N-methyl derivative

Summary A series of metal ion complexes of the thiosemicarbazone,N-methyl-2[1-(2-pyridinyl)ethylidene]-hydrazinecarbothioamide (HL4M) has been prepared and spectrally characterized. HL4M coordinates either as a neutral bidentate ligand (i.e., pyridyl N and imine N) or as deprotonated tridentate ligand (i.e., pyridyl N, imine N and thiol sulphur). The cobalt(II) salts yield hexacoordinated cobalt(III) cations, and an isoelectronic species, [Ni(L4M)₂], has been formed from Ni(C₂H₃O₂)₂. The remaining nickel(II) complexes involve the neutral ligand, as do two of the three copper(II) complexes. HL4M possesses a weaker ligand field and has less covalency in its bonding than related thiosemicarbazones that possess anN-dialkyl-function.     

Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridine. Part 5. The4 N-cyclohexyl derivative

Summary Metal ion complexes of the thiosemicarbazone,⁴ N-cyclohexyl-2-[1-(2-pyridinyl)ethylidene]hydrazinecarbothioamide (HL4CH), have been prepared and spectrally characterised. Both the size of the cyclohexyl-group attached at⁴N as well as the⁴N hydrogen affect the stoichiometry and stereochemistry of the isolated complexes. The large cyclohexyl-group evidently causes the isolation of [Fe(HL4CH) (L4CH)H₂O](ClO₄) instead of the expected [Fe(L4CH)₂]ClO₄[Co(L4CH)Br] instead of [Co(HL4CH)Br₂], and [Ni(L4CH)Br] instead of [Ni(HL4CH)₂Br₂]. The presence of the hydrogen at⁴N presumably hinders the deprotonation of HL4CH on complex formation since [Cu(HL4CH)Cl₂] was isolated rather than [CuLCl], which occurs when the thiosemicarbazone has⁴N with two alkyl groups or incorporated in a ring. Further, although we prepared [Ni(L4CH)Br], complexes of this stoichiometry are planar and diamagnetle when⁴N does not have a hydrogen(s) attached to it rather than tetrahedral and paramagnetic as has been found for the present complex.     

Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridine. Part 6. The chemical and antifungal properties of 2-acetylpyridine4 N-diethyl- and4 N-dipropylthiosemicarbazones and their copper(II) complexes

Summary Complexes of stoichiometry [CuLX] where X=Cl, Br and L=2-acetylpyridine⁴ N-diethyl- and⁴ N-dipropylthiosemicarbazone, HL4DE and HL4DP, respectively, have substantially more activity againstAspergillus niger andPaecilomyces variotii than the uncomplexed thiosemicarbazones. Spectral data (i.e., i.r., u.v.vis., and e.s.r) of the complexes are presented along with thermodynamic data for the thiosemicarbazones.     

Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridine. Part 9. The chemical and antifungal properties of the iron(III) and cobalt(II,III) complexes of 2-acetylpyridine4 N-diethyl-and4 N-diopropylthiosemicarbazones

Summary ⁴ N-diethyl- and⁴ N-dipropylthiosemicarbazones of 2-acetylpyridine coordinate to Fe^III, Co^III and Co^II centres as tridentate NNS ligands. Spectral and physical data indicates that the size of the⁴ N-substituents can influence the stereochemistry and stoichiometry of the complexes, which show minimal ability to inhibit fungal growth and are considerably less active than the related copper(II) and nickel(II) complexes.     

Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridine. Part 8. The chemical and antifungal properties of the nickel(II) complexes of 2-acetylpyridine4 N-diethyl- and4 N-dipropylthiosemicarbazones

Summary Nickel(II) complexes of 2-acetylpyridine⁴ N-diethyl- and⁴ N-dipropylthiosemicarbazone show less activity againstAspercallus niger than the free thiosemicarbazones. However, againstPaecilomyces variotii the nickel(II) complexes possess comparable activity at high concentrations and are more active at lower concentrations. Spectral and thermal information about the nickel(II) complexes, which coordinate the anionic thiosemicarbazone ligands in a tridentate manner, is included.     

Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridine. Part 3. The 3-hexamethyleneimine derivative

Summary Metal ion complexes of the thiosemicarbazone, 3-hexamethyleneimine-3-thiocarboxylic acid-2-[1-(2-pyridyl)-ethylidene]hydrazide (HLhexim) have been prepared and spectrally characterized. HLhexim coordinates primarily as the deprotonated tridentate ligand (i.e., pyridylN, azomethineN, and thione sulphur). The air oxidised cobalt(III) complex, [Co(LHexim)₂] (BF₄), was isolated from the preparation with cobalt(II) tetrafluoroborate, but other cobalt(II) salts yielded tetrahedral cobalt(II) compounds. Planar nickel(II) and copper(II) complexes were isolated from preparations with halide salts. Significant differences in the spectral properties of the various complexes are observed when compared to other thiosemicarbazones prepared from 2-acetylpyridine.     

Transition metal ion complexes of theS-methyldithiocarbazate prepared from 2-acetylpyridineN-oxide

Summary Metal ion complexes of theS-methyldithiocarbazate of 2-acetylpyridineN-oxide, HONS, have been prepared and characterised by spectral and physical methods. Preparative ethanolic solutions on reflux yield complexes in which the deprotonated form of the ligand, ONS, is complexedvia itsN-oxide oxygen, azomethine nitrogen, and thione sulphur. Representative stoichiometries are as follows: [M(ONS)₂]X (M=Fe³⁺, and X=ClO ₄ ^– , FeCl ₄ ^– or M=Co³⁺ and X=BF ₄ ^– ) and [M(ONS)X] (M=Co²⁺, Ni²⁺ and Cu²⁺ and X=Cl^–, Br^–). The i.r., electronic, and electron spin resonance spectra of the complexes are compared to analogous complexes of theX-methyldithiocarbazate of 2-acetylpyridine as well as the thiosemicarbazones of 2-acetylpyridineN-oxide.     

Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridine. Part 7. Chemical and antifungal properties of 2-acetylpyridine4 N-ethylthiosemicarbazone and its metal complexes

Summary Spectral and thermal information, as well as activity againstAspergillus niger, have been obtained for 2-acetylpyridine⁴ N-ethylthiosemicarbazone and its iron(III), cobalt(II,III), nickel(II) and copper(II) complexes.     

Iron(III) and nickel(II) template complexes derived from benzophenone thiosemicarbazones

New iron(III) and nickel(II) chelates were synthesized by template reaction of 2,4-dihydroxy- and 2-hydroxy-4-methoxy-benzophenone S-methylthiosemicarbazones with 2-hydroxy- and 5-bromo-2-hydroxy-benzaldehydes. The template complexes were isolated as stable solids and characterized by elemental analysis, conductivity and magnetic measurements, IR, ¹H NMR, UV–Visible, and mass spectra. The crystal structure of N ¹-(2-hydroxy-4-methoxyphenyl)(phenyl)methylene-N ⁴-(2-hydroxy-phenyl)methylene-S-methyl-thiosemicarbazidato-Fe(III) was determined by X-ray diffraction. A five-coordinate, distorted square-pyramidal geometry was established crystallographically for the iron(III) complex. Cytotoxicity and proliferation properties were determined using human erythromyeloblastoid leukemia and HL-60 mouse promyelocytic leukemia cell lines. For K 562 and HL-60 cells, compounds 1a and 2b were found to be cytotoxic at concentrations of 10 and 20 µg mL^?1.     

Iron(III) complexes of some thiosemicarbazones derived from 2-acetylpyridine,its 6-methyl derivative and itsN-oxide

Summary A series of iron(III) complexes of thiosemicarbazones derived from 2-acetylpyridine, 6-methyl-2-acetylpyridine and 2-acetylpyridineN-oxide have been prepared from Fe(ClO₄)₃ and FeCl₃. All of the isolated solids have cations involving two monobasic tridentate ligands, and either perchlorate or tetrachloroferrate(III) anions and are 11 electrolytes. Coordinationvia the pyridine nitrogen (or theN-oxide oxygen), the imine nitrogen and the sulphur atom are confirmed by infrared spectra and x-ray diffraction. The presence of two different iron(III) species is indicated by the electron spin resonance spectra of the tetrachloroferrate(III) solids. E.s.r. along with electronic spectra prove the spin-paired configuration of these cationic iron(III) complexes.NATO Fellow, on leave from Istanbul Medical Faculty, Istanbul University.     

Copper(II) complexes of thiosemicarbazones derived from 2-acetylpyridine and its n-oxide

A series of Cu(II) complexes of the thiosemicarbazone, 3-azabicyclo[3.2.2]-nonene-3-thiocarboxylic acid 2-[1-(2-pyridinyl)ethylidene]hydrazide(HL) and the corresponding N-oxide (HLO) have been prepared and characterized. Both ligands undergo deprotonation and appear to coordinate via the thione sulfur, the imine nitrogen and the pyridyl nitrogen (or N-oxide oxygen). A single anionic ligand such as Cl^?, Br^?, NCS^? and N^?₃ completes the bonding to the Cu(II) center of these 4-coordinate complexes. When the complexes are prepared using Cu(II) perchlorate, the solids isolated contain a neutral thiosemicarbazone ligand as well as the deprotonated ligand. The solids are primarily characterized by IR, electronic and electron spin resonance spectroscopy. In addition, electronic and ESR spectra of their chloroform solutions were recorded. Most of the solids (except the nitrates) were unaltered upon dissolution. Simulation of the solution ESR spectra was used to estimate the coupling constants of the various coordinated nuclei.     

Transition metal complexes with thiosemicarbazide-based ligands. Part 56. Square-pyramidal complexes of copper(II) with 2-acetylpyridine S-methylisothiosemicarbazone

The article describes the synthesis and single-crystal X-ray analysis of two sulfato and one thiocyanato copper(II) complex with 2-acetylpyridine S-methylisothiosemicarbazone (HL) of the formulae [Cu(HL)SO₄(H₂O)]·H₂O (1), [Cu₂(HL)₂(μ-SO₄)₂]·2H₂O (2) and [Cu(HL)(NCS)(SCN)] (3), as well as the structure of the protonated ligand H₂L⁺I⁻. Complexes 1 and 2 were obtained from the reaction of aqueous/methanolic CuSO₄·5H₂O and ethanolic/methanolic H₂L⁺I⁻ solutions, respectively. Complex 3 was synthesized by the reaction of methanolic solutions of Cu(ClO₄)₂·6H₂O, the ligand and NH₄SCN, with the addition of triethyl orthoformate. All three complexes have a slightly deformed square-pyramidal structure (τ_av = 0.15) with the tridentate NNN neutral ligand in the basal plane. In complexes 1 and 3 the apical position is occupied by the oxygen atom of the monodentate SO₄ group, or the sulfur atom of the SCN group. Thanks to the hydrogen bonds, complex 3 may be thought of as having a pseudo-dimeric structure. In the authentic centrosymmetric dimer 2, the oxygen atoms of both SO₄ groups occupy also the apical position of both coordination polyhedra, as well as an equatorial position. Complexes 1 and 3 have μ_eff values characteristic of magnetically isolated mononuclear Cu(II) complexes. In contrast to them, complex 2 has a μ_eff value of 1.57 BM, which is in agreement with its dinuclear structure. All the complexes, in addition to the X-ray analysis and magnetic measurements, were characterized by IR and UV–Vis spectroscopy and by thermal analysis.     

Transition metal complexes with Girard reagent-based ligands. Part IV. Synthesis and characterization of pyridoxilidene Girard-T hydrazone complexes. Crystal structure of the copper(II) complex

Abstract  The monoligand complexes of the formula M(HPLGT)(NCS)₂ (M = Cu(II), Zn(II)) in which the ligand tridentate ONO pyridoxilidene Girard-T hydrazone, [H₃PLGT]Cl₂ · 2H₂O, was coordinated in neutral doubly deprotonated form were synthesized. Also, the first complexes with the ligand coordinated in triply deprotonated monoanionic form of the formula [Cu(PLGT)N₃] and [Co(PLGT)(NO₂)₂NH₃] · 3H₂O are reported. The single crystal X-ray analysis of [Cu(HPLGT)(NCS)₂] showed that Cu(II) is placed in a square-pyramidal surrounding consisting of one tridentate Schiff base and one NCS group in the basal plane and the other NCS group in the apical position. Intermolecular hydrogen bonds leading to centrosymmetrical dimerization of these complexes were discussed. In the reaction of Girard-T and Hacac in the presence of CuCl₂, a mixture of single crystal complexes of the composition [Cu(3,5-Me₂pz)₂Cl₂]₂ and [Cu(acac)₂] · 2[Cu(3,5-Me₂pz)₂Cl₂] was obtained and X-ray analysis of the latter one was reported. Index abstract  Crystal structure of the Cu(II) complex with pyridoxilidene Girard-T hydrazone was analyzed. Additional two Cu(II) complexes obtained by the reaction of Girard-T reagent and Hacac in the presence of CuCl₂ were also studied by single crystal X-ray analysis.      

A spectral study of 2-formylimidazole 4N-substituted thiosemicarbazones and their copper(II) complexes

Copper(II) complexes of 2-formylimidazole ⁴N-methyl-, ⁴N-dimethyl- ⁴N-ethyl- and 3-hexa-methyleneiminylthiosemicarbazone, along with two nickel(II) complexes of the latter thiosemicarbazone, have been synthesized. Infrared, electronic, NMR and ESR spectra have been used to characterize the complexes and the uncomplexed thiosemicarbazones. None of the complexes or thiosemicarbazones possess growth inhibitory activity against Aspergillus niger and Paecilomyces variotii.     

Electrochemical studies of transition metal complexes of 2-acetyl-pyridine thiosemicarbazones. Part 2. Correlations with spectral and antifungal properties of copper(II) complexes of 2-acetylpyridine 3-azacyclothiosemicarbazones

The electrochemical behaviour of a series of copper(II) complexes of 2-acetylpyridine 3-azacyclothiosemicarbazones is reported. The complexes undergo a quasireversible one electron reduction in the range −0.400 to −0.450 Vversus Ag/AgCl, attributable to the copper(II)/-copper(I) redox couple. The electrochemical, as well as spectral characteristics of these complexes, can be correlated with their antifungal activity againstAspergillus niger, Paecilomyces variotti, Penicillum rubrum andAspergillus terreus.