N 1,N 4-diarylidene-S-ethylthiosemicarbazone iron(III) and nickel(II) complexes

Template reactions of salicyl-, 5-bromosalicyl- and 2-hydroxy-1-naphth-aldehyde with S-ethylthiosemicarbazones, in the presence of FeCl₃ and NiCl₂, yielded the corresponding N ¹,N ⁴-di(same/different)arylidene-S-ethylthiosemicarbazone complexes, which were characterized by elemental analysis, magnetic measurements, i.r. and ¹H-n.m.r. spectra.     

Oxovanadium(IV) complexes of bromo-and methoxy substituted N1,N4-diarylidene-S-methylthiosemicarbazones

Four new oxovanadium(IV) compounds were prepared by template reaction of salicyl-, 5-bromosalicyl-and 3-methoxysalicyl-aldehyde S-methylthiosemicarbazones with 2-hydroxy-, 5-bromo-2-hydroxy-and 3-methoxy-2-hydroxy-benzaldehyde in various combinations. The compounds were isolated as stable solid compounds with general formula [VO(L)] and characterized by elemental analysis, conductivity and magnetic measurements, electronic, IR and EPR spectroscopy. The X-band EPR signals recorded from powder forms of all samples have a single asymmetric line shape and theoretical fit studies proved the presence of axial symmetry around the paramagnetic vanadium ions. The anisotropic Lande splitting factors take values of g_‖ < g_⊥ < g_e = 2.0023. Orbital energy levels for magnetic electrons were determined from theoretically well fitted Spin Hamiltonian parameters. The EPR spectra recorded from solution forms almost have isotropic character.     

Synthesis,magnetic and spectral studies of iron(III), cobalt(II,III), nickel(II), copper(II) and zinc(II) complexes of 4–formylantipyrine N(4)-antipyrinylthiosemicarbazone

4–Formylantipyrine N(4)-antipyrinylthiosemicarbazone and its metal complexes have been synthesized and characterized. Elemental analyses, molar conductivities, magnetic measurements and spectral (i.r., electronic, n.m.r., e.s.r.) studies have been used to characterize the complexes. The i.r. spectra show that the thiosemicarbazones behave as bidentate (NS) or tridentate ligands (ONS), either in the thione or thiolato form. Stereochemistries are proposed for the complexes on the basis of both spectral and magnetic studies.     

Halogen substituted quadridentate schiff bases,their nickel(II) and cobalt(III) complexes

Summary Electrophilic substitutions have been performed on the methyne carbon of NiL and [CoL,2py]ClO₄ [L=N,N-bis(acetylacetone) ethylenediiminato-]. The effects of substituents (H, Cl, Br and I) on the electron distribution within the cobalt(III) complexes have been investigated through¹H and¹³C n.m.r., i.r. spectroscopy and half-wave potential measurements     

Synthesis and characterisation of complexes of iron(II,III), cobalt(II,III) and nickel(II) with dinitrosoresorcinol

Summary Complexes of Fe^II, Fe^III, Co^II, Co^III and Ni^II with dinitroso resercinol (DNR) have been isolated and characterised. Ni studies showed that the metals are coordinated to the oxygens of one hydroxyl and one nitroso group, the second hydroxyl and nitroso groups remaining uncoordinated. The magnetic moments of the Fe^II and Ni^II complexes are commensurate with tetrahedral (or disorted octahedral) structures, while the others are ocahedral, however, the electronic spectra suggest ocahedral stereochemistries for all the complexes.     

Synthesis,magnetic and spectral studies of iron(III), cobalt(II,III), nickel(II), copper(II) and zinc(II) complexes of 2–formylpyridine N(4)-antipyrinylthiosemicarbazone

2–Formylpyridine N(4)-antipyrinylthiosemicarbazone and its metal complexes have been synthesized and characterized. Elemental analyses, molar conductivities, magnetic measurements and spectral (i.e., i.r., electronic, n.m.r. and e.s.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. Ligand field parameters have been calculated and the proposed stereochemistries are based on the various physical and spectral methods.     

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.     

Intermediate spin iron(III) complexes of N4,N4-disubtituted 2-acetylpyridine thiosemicarbazone

Summary Magnetic susceptibility and Mössbauer spectroscopy measurements have been carried out on [Fe^III(SAm)Cl₂], and indicate an intermediate spin state for the ferric ion. The temperature-independent magnetic moment of (4.17±0.05) _B, the quadrupole splitting=4.09 mm s^–1 and isomer shift=0.133 mm s^–1 are in agreement with such formulation. These studies, together with infrared data, are used to suggest a possible structure of the complex.     

Activation volumes for peroxodisulphate oxidation of cobalt(III), iron(II) and nickel(II) complexes

Summary Dependences of rate constants on pressure (in aqueous solution up to 1.25 kbar) are reported for peroxodisulphate oxidation of hexacyanoferrate(II), tris(2,2-bipyridyl)iron(II), tris(1,10-phenanthroline)iron(II), bis(1,4,7-triazacyclononane)nickel(II) and bis(1,2-ethanediamine)cysteinatocobalt(III) and its thioglycollato-analogue, and for periodate oxidation of the two last-named complexes. Derived activation volumes are reported and discussed in terms of intrinsic and solvational contributions. Rate laws and pressure effects on reactivity are reported for the reaction of peroxodisulphate with pentacyanoferrates(II) containing N-alkylpyrazinium ligands.     

Heterogeneous reactions of solid nickel(II) complexes,III

The thermal decompositions of solid complexes of the type Ni(NCS)₂L₂ (L = pyridine,α-picoline,β-picoline, 2,6-lutidine, and quinoline) were studied by means of the derivatograph. It was found that the decompositions of complexes with pyridine,α-picoline, 2,6-lutidine, and quinoline (the pseudo-octahedral complex) are onestep processes, and those of complexes withβ-picoline and quinoline (the squareplanar complex) consist of two steps. Diffuse reflectance spectra were recorded to elucidate the structures of the decomposition intermediates. The reasons for the different stoichiometries of decomposition for complexes of the same type are discussed.     

Spin transition in iron(III) and iron(II) complexes

The main stages of the studies on the spin transitions in iron(III) and iron(II) complexes are considered. The types of the spin transitions and the factors responsible for the latter are reported. The problems arising during experiments in this field are discussed.     

Synthesis and characterization of biacetyldihydrazone complexes of cobalt(II), copper(II), nickel(II) and iron(III)

Summary Biacetyldihydrazone (BdH) complexes [M(BdH)₃](ClO₄)₂ (M=Co^IIor Cu^II) and [M(BdH)₃](NO₃)_2,3 (M = Ni^IIor Fe^III) have been prepared and characterized by chemical analysis, conductance measurements, electronic, i.r. and e.p.r. spectral studies and magnetic subsceptibilities measurements. A mononuclear octahedral configuration is proposed for all complexes studied.     

Mixed ligand complexes involving aminoacid dithiocarbamates,substituted phosphines and nickel(II)

Mixed ligand complexes involving four aminoacid dithiocarbamates (RRdtc=glydtc^– (R=H; R=H), methdtc^– (R=H; R=C₃H₇S), sardtc^– (R=Me; R=H), trydtc^– (R=H; R=C₉H₈N), substituted phosphines [PPh₃, Ph₂PCH₂CH₂PPh₂(dppe)] and nickel(II) are reported. All are diamagnetic. Thermal analyses of the complexes are in keeping with the proposed formulae. Thermal decomposition of the dithiocarbamate moiety proceeds through the formation of Ni(SCN)₂. PPh₃ and dppe are lost in the initial decomposition stages.     

Gaseous iron(II) and iron(III) complexes with BINOLate ligands

Electrospray ionization (ESI) of dilute solutions of 1,1'-bi-2-naphthol (BINOL) and iron(II) or iron(III) sulfate in methanol/water allows the generation of monocationic complexes of iron and deprotonated BINOL ligands with additional methanol molecules in the coordination sphere, and the types of complexes formed can be controlled by the valence of the iron precursors used in ESI. Thus, iron(II) sulfate leads to [(BINOLate)Fe(CH3OH)n]+ complexes (n=0-3), whereas usage of iron(III) sulfate allows the generation of [(BINOLdiate)-Fe(CH3OH)n]+ cations (n=0-2); here, BINOLate and BINOLdiate stand for singly and doubly deprotonated BINOL, respectively. Upon collision-induced dissociation, the mass-selected ions with n>0 first lose the methanol ligands and then undergo characteristic fragmentations. Bare [(BINOLdiate)Fe]+, a formal iron(III) species, undergoes decarbonylation, which is known as a typical fragmentation of ionized phenols and phenolates either as free species or as the corresponding metal complexes. The bare [(BINOLate)Fe]+ cation, on the other hand, preferentially loses neutral FeOH to afford an organic C20H12O+* cation radical, which most likely corresponds to ionized 1,1'-dinaphthofurane.     

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.     

Solid complexes of iron(II) and iron(III) with rutin

Solid complex compounds of Fe(II) and Fe(III) ions with rutin were obtained. On the basis of the elementary analysis and thermogravimetric investigation, the following composition of the compounds was determined: (1) FeOH(C₂₇H₂₉O₁₆)·5H₂O, (2) Fe₂OH(C₂₇H₂₇O₁₆)·9H₂O, (3) Fe(OH)₂(C₂₇H₂₉O₁₆)·8H₂O, (4) [Fe₆(OH)₂(4H₂O)(C₁₅H₇O₁₂)SO₄]·10H₂O. The coordination site in a rutin molecule was established on the basis of spectroscopic data (UV–Vis and IR). It was supposed that rutin was bound to the iron ions via 4C=O and 5C—oxygen in the case of (1) and (3). Groups 5C–OH and 4C=O as well as 3′C–OH and 4′C–OH of the ligand participate in binding metals ions in the case of (2). At an excess of iron(III) ions with regard to rutin under the synthesis conditions of (4), a side reaction of ligand oxidation occurs. In this compound, the ligands’ role plays a quinone which arose after rutin oxidation and the substitution of Fe(II) and Fe(III) ions takes place in 4C=O, 5C–OH as well as 4′C–OH, 3′C–OH ligands groups. The magnetic measurements indicated that (1) and (3) are high-spin complexes.     

New complexes of iron(III), cobalt(II), nickel(II) and copper(II) with 2-phenyl-1,2,3-triazole-4-carboxalidene-2-aminophenol

Summary Fe^III, Co^II, Ni^II and Cu^II complexes of a new Schiff base, 2-phenyl-1,2,3-triazole-4-carboxalidene-2-aminophenol (PTCAP), have been synthesized and characterized by elemental analyses, molar conductance and magnetic susceptibility measurements, and by u.v.-vis., i.r. and e.p.r. spectral observations. The studies indicate an octahedral structure for the complexes with the general formula [ML₂] (M = Co^II, Ni^II or Cu^II.; L = PTCAP) or [M′(OH)L₂] (M′ = Fe^III). The i.r. spectra suggest that the ligand acts as a tridentate (NNO) donor towards Co^II, Ni^II and Cu^II, and, in the Fe^III complex, one of the two ligand molecules acts as a bidentate (NO) donor and the other as a tridentate donor. The M?ssbauer spectrum of the Fe^III complex suggests the presence of a spin equilibrium at room temperature. Cyclic voltammograms are also recorded for the Cu^II and Fe^III complexes.     

Molecular and crystal structure of iron(III) and nickel(II) complexes with 1′-phthalazinylhydrazones of heterocyclic carbonyl compounds

Journal of Structural Chemistry - The structures of iron(III) and nickel(II) complexes with the composition [FeL2]Cl·H2O (1) and [Ni(HL′2)]·DMSO·0.5H2O (2), where L and...     

Complexes of 4-hydroxyphenylthiocarboxyhydrazide with iron(II), cobalt(II,III), nickel(II), copper(II) and zinc(II)

Summary The 4-hydroxyphenylthiocarboxyhydrazide (Hoth) ligand has been characterized by i.r.,¹H and¹³C spectral studies. Its metal complexes with Fe^II, Co^II,III, Ni^II, Cu^II and Zn^II have been prepared and characterized on the basis of elemental analyses, molar conductance, magnetic susceptibility. Mössbauer, visible, e.s.r., i.r.,¹H and¹³C n.m.r. spectral studies. The bonding and stereochemistry of the complexes are discussed. Hoth and its Cu^II complexes have been screened towards bacteria, viruses and fungi.