• Bulletin of the Korean Chemical Society
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• v.16 no.7
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• pp.619-624
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• 1995

Oxidation of triphenylphosphine to triphenylphosphine oxide by [(tpy)(bpy)Ru(O)]2+ (tpy is 2,2':6',2"-terpyridine and bpy is 2,2'-bipyridine) in CH3CN has been studied. Experiments with the 18O-labeled oxo complex show that transfer of oxygen from [(tpy)(bpy)RuⅣ=O]2+ to triphenylphosphine is quantitative within experimental error. The reaction is first order in each reactant with k (25.3 ℃)=1.25 × 106 M-1s-1. The inital product, [(tpy)(bpy)RuⅡ-OPPh3]2+, is formed as an observable intermediate and undergoes slow k (25 ℃)=6.7 × 10-5 s-1 solvolysis. Activation parameters for the oxidation step are ΔH≠=3.5 kcal/mol and ΔS≠=-23 eu. The geometry at ruthenium in the complex cation, [(tpy)(bpy)RuⅡ(OH2)]2+, is approximately octahedral with the ligating atoms being the three N atoms of the tpy ligand, the two N atoms of the bpy ligand, and the oxygen atom of the aqua ligand. The Ru-O bond length is 2.136(5) Å.

• Bulletin of the Korean Chemical Society
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• v.27 no.12
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• pp.2023-2027
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• 2006

Dibenzyl sulfide was oxidized at the a-carbon to yield benzaldehyde in the presence of $Pd(NO_3)_2$. Oxygen itself could not oxidize the sulfide directly, instead the nitrato ligand of the palladium complex transferred oxygen to dibenzyl sulfide to form benzaldehyde. The X-ray crystal structure of the intermediate complex, cis-[$Pd(NO_3)_2${$S(CH_2C_6H_5)_2$}$_2$], revealed that the nitrato ligand was unidentate. Para-substituted dibenzyl sulfides I, $(YC_6H_4CH_2)_2S $wherein Y = $OCH_3$, $CH_3$, Cl, CN, or $NO_2$, were synthesized and reacted with palladium nitrate, and those with electron-donating substituents (Y = $OCH_3$ and $CH_3$) were good substrates for the oxidation reaction with palladium nitrate. Thus, the reaction mechanism of the oxygen transfer was proposed to include nucleophilic benzylic carbon.

• Bulletin of the Korean Chemical Society
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• v.23 no.6
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• pp.851-856
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• 2002

The Reaction of S-methyl-S-cysteine(L-Smc) with racemic $s-cis-[Co(demba)Cl_2]-1$ (Hydmedba = $NN'-dimethylethylenediamine-NN'-di-\alpha-butyric$, acid) yields ${\Delta}$-s-cis-[Co(dmedba)(L-Smc)] 2 with N, O-chelation. Oxidation of sulfur of 2 with $H_2O_2$ in a 1 : 1 mole ratio gives ${\Delta}$-s-cis[Co(dmedba)(L-S(O)mc)] 3 having an uncoordinated sulfenate group. Oxidation of sulfur of L-Sm with $H_2O_2in$ a 1: 1 mole ratio produces S-methyl-L-cysteinesulfenate (L-S(O)me) 5. Direct reaction of 1 with 5 in basic medium gives an N.O-chelated ${\Delta}$s-cis[Co(dmedba)(L-S(O)mc)-N.O], which turmed out be same as obtained by oxidation of 2, while an N, S-chelated ${\Delta}$-s-cis-[Co(dmedba)(S-S(O)mc)-N,O] complex 4 is obtained in acidic medium from the reaction of 1 with 5. This is one of the rare $[$Co^{III}$(N_2O_2-type$ ligand)(amino acid)] type complex preparations, where the reaction conditions determine which mode of N, O and N, S caelation modes is favored.

• Journal of the Korean Chemical Society
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• v.59 no.3
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• pp.215-224
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• 2015

Unsymmetrical tetradentate Schiff base N-(2-hydroxy-5-methylacetophenone)-N'-(2-hydroxy acetophenone) ethylene diamine (H₂L) and its complexes with Cr(III), Mn(II), Fe(III), Co(II), Ni(II) and Cu(II) have been synthesized and characterized by elemental analyses, magnetic susceptibility measurements, IR, electronic spectra and thermogravimetric analyses. ¹H, ¹³C-NMR and FAB Mass spectra of ligand clearly indicate the presence of OH and azomethine groups. Elemental analyses of the complexes indicate that the metal to ligand ratio is 1:1 in all complexes. Infrared spectra of complexes indicate a dibasic quadridentate nature of the ligand and its coordination to metal ions through phenolic oxygen and azomethine nitrogen atoms. The thermal behavior of these complexes showed the loss of lattice water in the first step followed by decomposition of the ligand in subsequent steps. The thermal data have also been analyzed for the kinetic parameters by using Horowitz-Metzger method. The dependence of the electrical conductivity on the temperature has been studied over the temperature range 313-403 K and the complexes are found to show semiconducting behavior. XRD and SEM images of some representative complexes have been recorded. The antimicrobial activity of the ligand and its complexes has been screened against various microorganisms and all of them were found to be active against the test organisms. The Fe(III) and Ni(II) complex have been tested for the catalytic oxidation of styrene.

• Journal of the Korean Chemical Society
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• v.47 no.6
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• pp.585-590
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• 2003

Cobalt oxygen carrier complex N,N'-ethylenebis(3-methoxysalycylideneiminato)cobalt(II), Co(3MeOsalen) was prepared at $25{\circ}C$. UV and visible absorption spectra of the complex and hydrazobenzene were studied in non-aqueous solvent methanol in the range of wavelength 200-600 nm. The oxidation of hydrazobenzene by oxygen in non-aqueous solvent is catalysed by Co(3MeOsalen). In the presence of triphenylphosphine($PPh_3$), the rate decreases in methanol. This is presumably attributable to the coordination of $PPh_3$ to the Co(3MeOsalen), resulting in the catallytically inactive compound. The initial rates of the oxidation of hydrazobenzene with the ligand triphenylphosphine were measured by the theoretical values of the rates, Rate=$k_1+k_2K_1[P]/1+K_1[P]+K_1K_2[P]^2$. This fact would be a poorer σ-donor ligand than methanol.

• Bulletin of the Korean Chemical Society
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• v.32 no.11
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• pp.3904-3908
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• 2011

A new octahedral Ru(III) complex with a tripodal tetraamine ligand, tpea = tris[2-(1-pyrazoyl)ethyl]amine, has been prepared and characterized. The single crystal X-ray crystallographic study of the complex revealed that the complex has a near octahedral geometry with the tetradentate ligand and two chloride ions. Peroxidase activity was examined by observing the oxidation of 2,2'-azinobis(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) with hydrogen peroxide in the presence of the complex. Amount of $ABTS^{+{\bullet}}$ generated during the reaction was monitored by UV/VIS and EPR spectroscopies. After the initiation of the peroxidase reaction, $ABTS^{+{\bullet}}$ concentration increases and then decreases after certain time, indicating that both ABTS and $ABTS^{+{\bullet}}$ are the substrates of the peroxidase activity of the Ru(III) complex.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.2
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• pp.69-72
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• 2021

The reaction of ammonium ferric sulfate with sodium borohydride in laponite sol yields nanoiron colloidal solution. This solution in air forms transparent yellow brown solution. The resulting solution reacts with bidentate chelating ligands. The reaction products are characterized by UV-Vis absorption spectroscopy and X-ray diffraction. All compounds show metal to ligand charge transfer band in the region of 400~650 nm in UV-Vis absorption spectra. This indicates the formation of iron-ligand complex by air oxidation of nanoiron. Also, XRD patterns exhibit that the iron-ligand complex is intercalated in the interlayer of laponite.

• Proceedings of the Korean Society of Potoscience Conference
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• 2006.06a
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• pp.32-32
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• 2006

• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2537-2543
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• 2011

A self-assembled Al-bridged diiminopyridine-based ligand (3) was synthesized and characterized by FT-IR, ESI-MS and NMR spectroscopy. Electron spectral titrations were performed to confirm the formation of a novel trinuclear bis(imino)pyridyl iron(II) complex (4) upon addition of $FeCl_2$ into Al-bridged ligand 3 in methanol solution. Simultaneously, a typical bis(imino)pyridine-iron(II) complex (2) was synthesized and fully characterized. The X-ray crystal study of the iron(II) complex 2 disclosed a five-coordinate, distorted square-pyramidal structure with the tridentate N^N^N ligand and chlorides. The optimal molecular structure of 4 was obtained by means of molecular mechanics, which showed that each iron atom in the complex 4 is surrounded by two chlorides, a tridentate N^N^N ligand and one oxygen atom, supporting considerations about the possibility of six-coordinate geometry from MMAO or the ethylene access. A comparison of 4 with the reference 2 revealed a remarkable decrease of the catalytic activity and MMAO consumption (activity up to $0.41{\times}10^3\;kg\;{mol_{Fe}}^{-1}h^{-1}bar^{-1}$, Al/Fe = 650 for 4 and $7.02{\times}10^3\;kg\;{mol_{Fe}}^{-1}h^{-1}bar^{-1}$, Al/Fe = 1600 for 2).

• Korean Chemical Engineering Research
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• v.43 no.2
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• pp.202-205
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• 2005

The effects of ligands on reactivity under GoAgg oxidation system have been studied. Picolinic acid containing carboxylic acid showed the most excellent activity among various ligands. Also, Picolinic acid of ortho position carboxylic group in pyridine ring largely increased reaction rates in the GoAgg oxidation systems. From these results, we proposed the new mechanism on the GoAgg oxidation using ligands having carboxylic group at ortho position.