Spectroscopic and electrochemical properties of iron(II) complexes of polydentate Schiff bases containing pyrazine, pyridine and imidazole groups

Souza, Vagner Roberto de; Rechenberg, H.; Bonacin, Juliano Alves; Toma, Henrique E.

doi:10.1016/j.saa.2008.04.001

Cited by 12 publications

(5 citation statements)

References 32 publications

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“…The coordination of the C N imine functionality to the iron center was observed by a shift of the imine stretch in the IR from 1626 to 1644 cm -1 in the free ligands to lower wavenumbers between 1590 and 1598 cm -1 upon imine coordination, which are in the same range than for other iron imine complexes reported in the literature (see Table 1, which compiles key physical data of the new complexes). 63 Non-coordinated OTf gives IR stretches at 1268, 1223, 1143, and 1030 cm -1 ; the solid state IR spectra of the complexes also showed these signals; some of the signals are desymmetrized, as previously reported for iron coordinated OTf. 64, 65 New bands associated with metal to ligand charge transfer (MLCT) processes were observed in the UV-vis spectra, which also indicated the formation of the new complexes (Table 1, vide infra).…”

Section: Synthesis Of A-iminopyridine Ligands and Iron Complexessupporting

confidence: 62%

“…An absorption in the same region has been previously reported for structurally related Fe(II) complexes with tetradentate imine pyridyl ligands, and was also ascribed to a MLCT transition. 63 The shoulders in the UV-vis spectrum of 8a and 8e might be due to second isomers in solution, which also were observed by 1 H NMR spectroscopy.…”

Section: Uv-vis Spectroscopymentioning

confidence: 64%

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New iron(ii) α-iminopyridine complexes and their catalytic activity in the oxidation of activated methylene groups and secondary alcohols to ketones

2011

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A set of iron(II) complexes of the general formula [Fe(OTf)(2)L(2)] was synthesized in 32 to 78% isolated yields, where L represents a bidentate α-iminopyridine ligand. Four of the iron complexes were characterized structurally, revealing a rich coordination chemistry, because the coordination geometry of the iron complexes strongly depends on the substitution pattern exhibited by the ligands L. The catalytic activity of the new complexes was demonstrated in the oxidation of cyclohexane, activated methylene groups and secondary alcohols to the corresponding ketones utilizing H(2)O(2) and t-BuOOH as the oxidants. The oxidation of activated methylene groups and secondary alcohols to the corresponding ketones with t-BuOOH gave isolated yields between 22 and 91% (4 h, room temperature, 3% catalyst load). The influence of the structure of the ligand on the activity of the corresponding metal complex is also reported. Furthermore, UV-vis experiments were performed which provided evidence for the formation of an [Fe-O-O-t-Bu] intermediate.

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Section: Synthesis Of A-iminopyridine Ligands and Iron Complexessupporting

confidence: 62%

Section: Uv-vis Spectroscopymentioning

confidence: 64%

New iron(ii) α-iminopyridine complexes and their catalytic activity in the oxidation of activated methylene groups and secondary alcohols to ketones

2011

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“…complexes, most of which have been proven to be efficient catalysts. [ 20–26 ] In fact, the imidazolyl moiety itself is a fine chelating agent towards platinum due to the electron donating N atoms on its rigid ring, and several platinum‐imidazolyl complexes have been reported in the literature. [ 27–30 ] When it is further converted into a Schiff base, its chelating ability is further enhanced as the number of donating atoms increase, thus increasing its ability to form platinum complexes.…”

Section: Introductionmentioning

confidence: 99%

Platinum‐Imidazolyl Schiff Base Complexes Immobilized in Periodic Mesoporous Organosilica Frameworks as Catalysts for Hydrosilylation

Huo

et al. 2020

Applied Organom Chemis

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An imidazolyl Schiff base-containing periodic mesoporous organosilica (PMO) was synthesized via co-condensation reactions between a newly prepared bis (imidazolyl)imine-bridged bis silane and tetraethyl orthosilicate in the presence of cetyltrimethyl ammonium bromide as a soft template. The resultant assynthesized PMO was then employed as a solid support for platinum catalysts. This complex was fully characterized via various techniques including FTIR, solid-state 13 C NMR, and 29 Si-NMR spectroscopy, as well as N 2 adsorption/desorption analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) methods. In addition, the catalyst was proven to efficiently mediate hydrosilylation reactions between olefins and hydrosilanes, and it can be reused for at least five cycles without significant loss of activity.

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“…To better understand hexa-and tetra-coordination of complexes ( 4) and (5), 3D molecular modeling of the proposed structure was carried out by CsChemOffice 3D Ultra 12.0.1 and ArgusLab 4.0.1 version software program package [50,51].…”

Section: Molecular Modeling Studymentioning

confidence: 99%

Coordination Chemistry, Antibacterial Screening, and In Silico ADME Study of Mononuclear NiII and CuII Complexes of Asymmetric Schiff Base of Streptomycin and Aniline

Chaudhary

Guragain

2022

Journal of Chemistry

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Two novel metal complexes, that is, Ni (StmAn)2(4) and Cu (StmAn)2(5), were synthesized from unsymmetrical Schiff base ligand StmAn (3). The ligand was prepared by refluxing streptomycin (2) and aniline (1). They were characterized by elemental microanalysis, conductivity measurements, and spectroscopic techniques such as 1H NMR, FT-IR, ESI-mass, and electronic absorption spectral study. Interestingly, the study revealed metal coordination through azomethine nitrogen and N-atom of NH-CH3 of N-methyl-L-glucosamine unit of streptomycin. The electronic absorption spectral study supported an octahedral geometry for complex 4 and a tetrahedral geometry for complex 5. Particle size calculation by Scherrer’s formula indicated their nanocrystalline nature. The geometry optimization of the complexes was achieved by running an MM2 job in Gaussian supported Cs-ChemOffice ultra-12.0.1 and ArgusLab 4.0.1 version software. Based on SwissADME predictions, a theoretical drug profile was generated by analyzing absorption, distribution, metabolism, excretion, and toxicity (ADMET) scores of the compounds. They were screened for in vitro antibacterial activity study against four clinical pathogens such as E. coli, S. pneumoniae, P. vulgaris, and S. aureus. Minimum inhibitory concentration (MIC) study demonstrated greater inhibitory potency of complex (4) (0.024 g/L) for S. aureus relative to ligand (3) and complex (5). Studies show that metal complexes are more toxic to bacteria.

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Spectroscopic and electrochemical properties of iron(II) complexes of polydentate Schiff bases containing pyrazine, pyridine and imidazole groups

Cited by 12 publications

References 32 publications

New iron(ii) α-iminopyridine complexes and their catalytic activity in the oxidation of activated methylene groups and secondary alcohols to ketones

New iron(ii) α-iminopyridine complexes and their catalytic activity in the oxidation of activated methylene groups and secondary alcohols to ketones

Platinum‐Imidazolyl Schiff Base Complexes Immobilized in Periodic Mesoporous Organosilica Frameworks as Catalysts for Hydrosilylation

Coordination Chemistry, Antibacterial Screening, and In Silico ADME Study of Mononuclear NiII and CuII Complexes of Asymmetric Schiff Base of Streptomycin and Aniline

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