• Journal of the Korean Chemical Society
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• v.44 no.6
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• pp.518-525
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• 2000

The open-chain hexadentate N$_4$, O$_2$ ligands 1,13-bis(2-hydroxybenzyl)-2,5,9,12-tetraazatridecane-tetrahydrochloride (BSATD${\cdot}$4HCl) and 1,14-bis (2-hydroxybenzyl)-2,6,9,12-tetraazatetradecane-tetrahydrochloride (BSATED${\cdot}$ 4HCl) have been synthesized as their tetrahydrochloride salt and characterized by EA, IR, NMR and Mass. Their proton dissociation constants(log$K^{n}_{H}$) and stability constants(log$K_{ML}$) for Cu(II), Ni(II), Co(II), and Zn(II) ions were determined in aqueous solution by potentiometry and compared with those of analogous N$_4$, O$_2$ ligands contain ethylenic spacers or propylenic spacers, which make six-membered chelate rings between the aliphatic nitrogen atoms. Synthesis and characterization of [Cu(BSATD)]ClO$_4$ and [Cu(BSATED)](ClO$_4$)$_2$ complexes are described.

• Journal of the Korean Chemical Society
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• v.33 no.6
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• pp.571-576
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• 1989

The relativistically parameterized Extended Huckel (REX) calculations are carried out for $[M(NH_3)_5Cl]^{2+}$ (M = Cr, Co, Ru, Rh, Os, Ir). The calculated orbital and overlap populations agree with experimental data. The REX calculations on the electronic structure have been also compared with nonrelativistic EHT results. A ${\phi}$-bonding in M-Cl bond is founded to be more important for the $d^3$, $d^5$complexes than the $d^6$ system.

• Journal of the Korean Chemical Society
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• v.31 no.6
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• pp.520-526
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• 1987

A new series of $dioxo-di-\mu-oxo-dimolybdate(V)$, has been prepared by reaction of pyridinum oxoisothiocyantomolybdate (V) with iminodiacetic acid derivatives containing amine carboxyl groups. The properties and possible molecular structure of these complexes were discussed by elemental analysis, spectroscopic studies and magnetic susceptibility measurements. The infrared spectra of these complexes all show two strong $Mo=O_t$ stretching bands in the 900∼$980cm^{-1}$, $MoO_2Mo$ very prominent strectching bands at around 410~425 and 735~$750cm^{-1}$ to symmetrical and asymmetrical O-bridge stretching, a coordinated $coo^-$ asymmetrical band in the 1585∼$1,640cm^{-1}$. Also, d-d transition of molybdenyl complexes corresponding to $^2B_2{\to}^2B_1$ occured in the 24,800~$28,000cm^{-1}$ region, charge transfer transition corresponding to ligand-to-molybdenum in the 32,500~33,800, 42,000~$47,500cm^{-1}$ region. The complexes synthesized were yellow or orange and diamagnetic.

• Journal of the Korean Chemical Society
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• v.29 no.3
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• pp.257-264
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• 1985

Dioxobis(3-methoxysalicyaldehydato)molybdeum(VI) complex has been synthesized by reactions of 3-methoxysalicylaldehyde and ammonium paramolybdate in methanol solution. With appropriate primary amine, the resulting complex gave schiff-base complexes, MoO$_2$(CH$_3$O-sal-N-R)$_2$ in which C=O oxide ligands had been replaced by nitrogen. The properties and possible molecular structure of these complexes were discussed by elemental analysis, spectroscopic studies and electric conductivities measurements. It was found that the Mo(VI) complexes contain a cis-MoO$_2$ group since their infrared spectra two Mo=O band at about 900cm$^{-1}$ and the combining ratios for MoO$_2$-ligand are 1 : 2. Also, electronic spectra of molybdenyl complexes assigned to ligand-to-metal charge transfer transition. All of these complexes are yellow or orange, depolar compound and slightly soluble in alcohol, dichloromethane, chloroform and N,N-dimethylformamide.

• Journal of the Korean Chemical Society
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• v.36 no.1
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• pp.3-15
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• 1992

Electronic structures and reactivities of the chromium, molybdenum, and tungsten carbene complexes, $(CO)_5Cr=CCHCH_2(XCH_3)\;,\;(CO)_5Mo=CCHCH_2(XCH_3)\;, and\;(CO)_5W=CCHCH_2(XCH_3)$, are studied by means of Extended Huckel calculations. The origin of the M=Ccarbene double bond is clarified from the diagram of the orbital correlation with the fragment orbitals. The ${\sigma}$ bond of the M=Ccarbene double bond is formed by the electron transfer interaction from the HOMO of the carbene to the LUMO of the $(CO)_5M$. The ${\pi}$ bond is formed through the back-transfer of electrons from one of the degenerated d${\pi}$ orbitals to the LUMO of the carbene. The polarization of charge of the M=Ccarbene bond is calculated to be M=Ccarbene for Mo, and W carbenes. The chemical and physical properties of these complexes are resulted from an appreciable positive charge on the carbene carbon. The electrophilic reactivity of the carbene carbon is not charge controlled, but is controlled by the frontier orbital, LUMO.

• Journal of the Korean Chemical Society
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• v.44 no.3
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• pp.298-301
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• 2000

• Journal of the Korean Chemical Society
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• v.35 no.2
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• pp.119-127
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• 1991

The protonation and the metal ion complexation of 15 to 18 membered diaza crown ether such as 1,12-diaza-3, 4 : 9, 10-dibenzo-5, 8-dioxacyclopentadecane(NtnOenH$_4$), 1,13-diaza-3,4 : 10,11-dibenzo-hydroxy-5,9-dioxacyclohexadecane(NtnOtnH$_4$), 1,13-diaza-3,4 : 10,11-dibenzo-15-hydroxy-5,9-dioxacyclohexadecane(Ntn(OH)OtnH$_4$), 1,15-diaza-3,4 : 12,13-dibenzo-5,8,11-trioxacycloheptadecane (NenOdienH$_4$) and 1,15-diaza-3,4 : 12,13-dibenzo-5,8,11-trioxacyclooctadecane(NtnOdienH$_4$) were studlied by potentiometry and NMR spectroscopy. The protonation constants were used to predict basicity of crown ethers. The sequence of the basicity was NenOdienH$_4$ < Ntn(OH)OtnH$_4$ < NtnOenH$_4$ < NtnOtnH$_4$ < NtnOdienH$_4$. Changes on the basicity were explained in terms of the effects of substituents and the degree of twistness of the macrocyclic ring. The sequence of the complex stabilities were Co(II) < Ni(II) < Cu(II) < Zn(II) for the transition metal complexes and Cd(II) < pb(II) < Hg(II) for the post-transition metal complexes. These changes on the stabilities were dependent on the basicity of the ligand and cavity size of the ring. For the heavy post-transiton metal complexes and Zn(Ⅱ) complex, the former factor was predominent and for the other transition metal complexes, the latter was affected on the stabilities. $^1$H and $^{13}$C-NMR studies for heavy post-transition metal complexes indicated that the nitrogen atom has greater affinity on metal ions than oxygen atom and the planarity of the rings was losed by the complexation with metal ions.

• Journal of the Korean Chemical Society
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• v.54 no.5
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• pp.541-550
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• 2010

A new $N_4O_3$ heptadentate ligand, N,N'-Bis(2-hydroxybenzyl)-1,3-bis[(2-aminoethyl)amino]-2-propanol(H-BAP 4HCl)was synthesized. The hydrochloric acid salts of Br-BAP 4HCl, Cl-BAP 4HCl, $CH_3O$-BAP 4HCl and $CH_3$-BAP 4HCl containing Br-, Cl-, H-, $CH_3O-$ and $CH_{3^-}$ groups at the para-site of the phenol group of the H-BAP were synthesized. The structures of the ligands were confirmed by C. H. N. atomic analysis and $^1H$ NMR, $^{13}C$ NMR, UV-visible and mass spectra. The elemental stepwise protonation constants(${logK_n}^H$) of the synthesized $N_4O_3$ ligands showed six steps of the proton dissociation. The orders of the overall dissociation constants($log{\beta}_p$) of the ligands were Br-BAP < Cl-BAP < H-BAP < $CH_3O$-BAP < $CH_3$-BAP. The orders agreed well with that of Hammett substituent constants($\sigma_p$). The calculated stability constants($logK_{ML}$) between the ligands and transition metal ions agreed well with the order of the overall proton dissociation constants of the ligands but they showed a reverse order in Hammestt substituent constants($\sigma_p$). The order of the stability constants between the transition metal ions with the ligands were Co(II) < Ni(II) < Cu(II) > Zn(II) > Cd(II) > Pb(II).

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.719-725
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• 1998

Tridentate Schiff base ligands were prepared by the reactions of salicylaldehyde and 2-hydroxy-1-naphthaldehyde with 2-aminophenol and 2-amino-p-cresol. And then Cu(II) complexes of those ligands were synthesized. The structures and properties of ligands and their complexes were studied by elemental analysis, $^1H$-NMR, IR, UV-visible spectra, and thermogravimetric analysis. The mole ratio of Schiff base to the metal of complexes was found to be 1:1. Cu(II) complexes were contemplated to be four-coordinated square planar configuration containing one water molecule. The redox process of ligands and complexes in DMSO solution containing 0.1 M TBAP as a supporting electrolyte was investigated by cyclic voltammetry and differential pulse voltammetry with glassy carbon electrode. The redox process of the tridentate Schiff base ligands was totally irreversible. The redox process of Cu(II) complexes was quasi-reversible and diffusion-controlled as one electron by one step process Cu(II)/Cu(I). The reduction potentials of the Cu(II) complexes shifted in the positive direction in the order of [Cu(II)(HNIPC)($H_2O$)]>[Cu(II)(HNIP)($H_2O$)]>[Cu(II)(SIP)($H_2O$)]>[Cu(II)(SIPC)($H_2O$)].

• Journal of the Korean Chemical Society
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• v.50 no.2
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• pp.99-106
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• 2006

The electronic absorption spectra of [3-(2-thenoyl) 3-(p-NO2-phenylhydrazone) ethyl pyruvate] (I), p-Br (II) and p-CH3 (III) were studied in ethanol and the spectra comprise four absorption bands which assigned to the corresponding electronic transition. The pK values of these compounds have been determined spectrophotometrically and pH-metrically, the results shown that the interval range for color change of compound (I) is (8-10) similar to that of phenolphethalin indicator, indicating that this compound can be used as acid-base indicator. The successive stability constants of the compounds under study with some transition elements (Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), UO2(II), La(III) and Zr(IV) have been determined pH- metrically. Stoichiometric complexes with ratios 1:1 and 1:2 (M: L) were formed for all metals. The pK of the three derivatives and the values of the stability constant (logK) of the complexes have the order; III > II > I. Also conductometric titrations have been carried out and the results show that this titration can be used for determination of both the metal ion and the ligand concentrations by each others.