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-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-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-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 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 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-acetylpyridineN-oxide. Part IV. Iron(III) and copper(II) complexes of the4 N-ethyl- and4 N-diethylthiosemicarbazones

Summary Copper(II) and iron(III) complexes of 2-acetylpyridineN-oxide⁴ N-ethyl- and⁴ N-diethylthiosemicarbazones have been prepared and characterized by physical and spectral methods. The⁴ N-ethyl-derivative coordinates as a neutral, bidentate ligand with copper(II), and the⁴ N-diethyl- as an anionic, tridentate ligand with both copper(II) and iron(III). The former ligand forms a mixed ligand complex (i.e., one neutral and one anionic ligand) with iron(III).     

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.     

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 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 complexes derived from 2-mercaptobenzothiazole

Summary Complexes of ethyl S-(2-benzothiazolyl)mercaptoacetate (e.s.m.) with Mn^II, Co^II, Ni^II, Cu^II and Zn^II have been prepared and their structures assigned on the basis of analytical, spectral (i.r., electronic, e.p.r. and XPS), magnetic data, molar conductance and t.g.-d.t.a. methods.     

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.     

Transition metal ion complexes of a thiosemicarbazone derived from 6-methyl-2-acetylpyridine

Summary A series of metal ion complexes of the thiosemicarbazone, 3-azabicyclo[3.2.2]nonane-3-thiocarboxylic acid 2-[1-(6-methyl-2-pyridinyl)ethylidene]hydrazide (6 MLH) have been prepared and spectrally characterized. The ligand undergoes deprotonation to coordinatevia the thione sulphur, the imine nitrogen and the pyridyl nitrogen. A single anionic ligand such as Cl^–, Br^– and NO₃ ^– completes the bonding to the Cu^II and Ni^II centre. The compound derived from CoCl₂ contains two 6 MLH ligands bound to a Co^II centre and a CoCl ₄ ^2– counter ion. Complexes derived from perchlorate salts may feature 6 MLH, 6 ML, or both with the Co^II being oxidized to Co^III. The solids were characterized by i.r., electronic and e.s.r. spectroscopy. In addition, electronic and e.s.r. spectra of their chloroform solutions were recorded.NATO Fellow, on leave from Istanbul Medical Faculty, Istanbul University.     

Transition metal complexes derived from 2-iminocyclohexanedithiocarboxylic acid

Summary The ligating properties of 2-iminocyclohexanedithiocarboxylic acid were investigated. Complexes with halides of manganese(II), iron(II), cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II) and mercury(II) were synthesized and characterized by elemental analysis, magnetic measurements, electron and i.r.¹H n.m.r. spectral studies. The results are concordant with a bidentate coordination of the—CS₂ group to the metal ions.     

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 theS-methyldithiocarbazate prepared from 2-acetylpyridine

Summary Metal ion complexes of 2-acetylpyridineS-methyldithiocarbazate, HNNS, have been prepared and spectrally characterised. Preparations in EtOH yield complexes in which the deprotonated ligand, NNS, is complexedvia its pyridyl nitrogen, azomethine nitrogen, and thione sulphur. The stoichiometries are: [M(NNS)₂]X (M=Fe³⁺, Co³⁺ and X=ClO ₄ ^– , [FeCl₄]^–, BF ₄ ^– , 1/2 [CoCl₄]^2– and 1/2 [CoBr₄]^2–), [M(NNS)X] (M=Ni²⁺, Cu²⁺ and X=Cl^–, Br^–), [Cu(NNS)H₂O]BF₄ and Ni(HNNS)(NNS)F(EtOH)]BF₄. The spectral (i.e., i.r., u.v.-vis.-n.i.r. and e.s.r.) and physical properties of these complexes are compared to those of theS-methyldithiocarbazates of 2-formylpyridine and 2-acetylpyridineN-oxide, as well as the related thiosemicarbazones prepared from 2-acetylpyridine. Thermal studies of the nickel(II) complexes indicate that the nature of thermal decomposition of coordinated NNS is different from that of HNNS.     

Transition metal ion complexes of 2-methylsulfinylpyridine n-oxide

Transition metal ion complexes in which 2-methylsulfinylpyridine N-oxide acts as a bidentate ligand have been prepared and characterized by molar conductivity measurements as well as IR and electronic spectra. Crystal field parameters are calculated for the Cr(III), Co(II) and Ni(II) solids based on octahedral symmetry from solid state spectra. Optical electronegativity calculations indicate that the charge transfer bands are metal-ligand in nature.