• Bulletin of the Korean Chemical Society
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• v.8 no.2
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• pp.122-126
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• 1987

Oribtal energies for AuH and AgH are calculated by an all-electron relativistic self-consistent-field method using Slater type basis functions. Major relativistic effects for AgH are spin-orbit splittings and those for AuH are large shifts in orbital energies in addition to spin-orbit splittings. Relativistic effects on orbital energies in AgH and AuH imply that changes in correlation energies for relativistic calculations of AuH will be significantly larger than those of AgH, providing partial explanation for the large discrepencies in equilibrium bond length and the dissociation energy between experiments and theoretical estimates for AuH. Large relativistic effects on orbital energies indicate that relativistic contributions should be included for the correct interpretation of ionization potentials for these molecules. Relativistic effects are also evident in dipole moments for these molecules.

• Bulletin of the Korean Chemical Society
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• v.18 no.7
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• pp.730-733
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• 1997

Monofluoroiron(Ⅲ) tetraphenylporphyrin, Fe(TPP)F, and difluoroiron(Ⅲ) tetraphenylporphyrin, [Fe(TPP)F2]- were generated in a various non-aqueous solvents by the reaction between Fe(TPP)Cl and tetrabutylammonium fluoride TBAF 3H2O. Formation of the these complexes was detected by the appearance of the ν(F-Fe) (ν, stretching vibration) at 506 cm-1 for Fe(TPP)F and the ν(F-Fe-F) at 448 cm-1 for [Fe(TPP)F2]-, simultaneously, with 441.6 nm excitation by Resonance Raman (RR) spectroscopy. These assignments were confirmed by observed frequency shifts due to 56Fe/54Fe and TPP/TPP-d8/TPP-N15 isotopic substitutions. Difluoroiron complex is an iron(Ⅲ) high-spin complex with the oxidation sensitive band at 1347 cm-1 for ν4 and core size/spin state sensitive band at 1541 cm-1 for ν2.

• Bulletin of the Korean Chemical Society
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• v.19 no.8
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• pp.840-846
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• 1998

The mechanism by which pyrrhotite is depressed by diethylenetriamine (DETA) during pentlandite flotation has been studied. Amyl xanthate is observed to adsorb on pyrrhotite to form both dixanthogen and iron xanthate. In the presence of DETA, the amount of xanthate adsorbed on pyrrhotite is substantially reduced as evidenced by infrared and UV/Vis spectroscopy. However, DETA does not adsorb on pyrrhotite as evidenced by infrared and X-ray photoelectron spectroscopy. DETA shifts the potential of the onset of xanthate adsorption on pyrrhotite by approximately 200 mV toward anodic direction, which is thought to be due to the increased solubility of surface oxidized species on pyrrhotite in the presence of DETA. A window of selectivity for the separation of pentlandite and pyrrhotite is provided by the results obtained in this study.

• Bulletin of the Korean Chemical Society
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• v.22 no.9
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• pp.989-993
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• 2001

The carbonyl stretching vibration, νC=O of 2-cyclohexene-1-one, is in Fermi resonance with a combination tone. The amount of Fermi resonance interaction between these two modes is dependent upon the amount of solute/solvent interaction due to hyd rogen bonding between the carbonyl oxygen and the solvent proton. The corrected νC=O frequency of 2-cyclohexene-1-one occurs at a lower frequency than the observed νC=O mode of cyclohexanone, possibly caused by expanded conjugation effects. The carbonyl stretching modes of cyclic ketones were also affected by interaction with the ROH/CCl4 mixed solvent system.

• Bulletin of the Korean Chemical Society
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• v.15 no.12
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• pp.1050-1054
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• 1994

Eu(Ⅲ) exhibits one electron-transfer reduction at E$_{1/2}$ =-0.617 V vs. Ag/AgCl and the hypersensitive peak at 618 nm corresponding to $^5D_0$ ${\leftrightarro}$ $^7F_2$ transition in 0.10 M LiClO$_4$ aqueous solutions. Upon the addition of carboxylate or sulfonate anions to the Eu(Ⅲ) aqueous solutions, the reduction potential shifts negatively and the reduction current decreases because of the complex formation between Eu(Ⅲ) ions and the anions. However, for the case of carboxylate anion (acetate or propionate) the shift of reduction peak potential and the emission intensity at 618 nm are greater. The results are interpreted in terms of the differences in the formation constants and the hypersensitivity.

• Bulletin of the Korean Chemical Society
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• v.17 no.11
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• pp.1052-1056
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• 1996

The effects of β-CD, Me-β-CD, and biphenyl capped β-CD on 1H NMR spectra of mandelic acid 1, α-methylbenzylamine 2 and 2-phenylpropionic acid 3 were investigated. Enantiomeric recognition was observed for mandelic acid 1 by all the hosts used, for α-methylbenzylamine 2 by β-CD and Me-β-CD, and for 2-phenylpropionic acid 3 by Me-β-CD. In the presence of biphenyl-capped β-CD, ο-, m-, and p-protons of the phenyl groups of the guests are discriminated due to ring current of the capped biphenyl group. The splitting pattern of the phenyl protons indicates that the phenyl group of the guests is inserted into the β-CD cavity from the secondary hydroxyl side and positioned in close proximity to the capped biphenyl ring. The magnitude of the upfield shifts of H3 and H5 protons of β-CD upon binding of guests 1-3 is similar to that caused by ephedrine or pseudoephedrine, suggesting that the substitution at benzylic carbon atom has little effect on the depth of the insertion of the phenyl group into the β-CD cavity and stability of the inclusion complexes.

• Bulletin of the Korean Chemical Society
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• v.16 no.5
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• pp.449-453
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• 1995

An exact quantum mechanical theory is employed to treat predissociation process of the $A^2{\Sigma}^+$ state of OH. The widths and positions of the lower (v= 2 and v= 3) rovibrational levels are calculated. Energy shifts of the resonances from the zeroth order (pure Hund'scase (b)) positions are shown to be small for N $\leq$ 10, indicating that the $A^2{\Sigma}^+$ state can be described as case (b) very well for low N. Due to the differential interactions of the $A^2{\Sigma}^+_{1/2}$ and $A^2{\Sigma}^+_{-1/2}$ states with $X^2II$and $2^2II$ states, small splittings between the $F_1$ and $F_2$ levels are predicted. Calculated lifetimes of the resonances agree with experimental results reasonably well.

• Bulletin of the Korean Chemical Society
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• v.20 no.9
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• pp.1056-1060
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• 1999

New water soluble and highly electron deficient cobalt(II) tetrakis-(1,2,5,6-tertrafluoro-4-NN'N"-trimethyla-nilinium)-β-octabromoporphyrin [Co II (Br8TTFP)(Y)2] was synthesized and used for the electrocatalytic reduction of dioxygen. The first reduction of synthesized [Co II (Br8TTFP)(Y)2] involves one electron process to give metal centered [Co I (Br8TTFP)(Y)2]. The reduction of potential [E1/2 = -0.32 V] of [Co II (Br8TTFP)(Y)2] shifts positively 370 mV compared with that of [Co II (TTFP)(Y)2] due to the substituted bromide to β-pyrrole positions. The electrochemically reduced [Co I (Br8TTFP)(Y)2] binds dioxygen and catalytically reduces it to HOOH by 2e - transfer. Cyclic and hydrodynamic voltammetry at a glassy carbon electrode in dioxygen-saturated aqueous solutions are used to study the electrocatalytic pathway.

• Bulletin of the Korean Chemical Society
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• v.17 no.12
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• pp.1154-1157
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• 1996

The growth and electronic properties of ultrathin silver films deposited onto Pt(211) surface were studied using Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), and x-ray photoelectron spectroscopy. The AES and LEED results indicate that the silver grows by a layer by layer growth followed by three dimensional islands growth. The XPS results show that the Ag 3d core-level binding energy of Ag overlayers on Pt(211) shifts toward lower binding energy relative to the bulk value at lower Ag coverage. This negative binding energy shift of the Ag 3d core level is explained by the reduced coordination number of the overlayer atoms and the resulting initial state band narrowing effect suggested by Wertheim and Citrin [Phys. Rev. Lett. 1978, 41, 1425].

• Bulletin of the Korean Chemical Society
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• v.16 no.12
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• pp.1176-1179
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• 1995

1H NMR spectra of pyridine, α-, β-, and γ-picoline coordinated to the paramagnetic heteropolyanion [Ni3(PW9O34)2]12- (P2Ni3) are reported. NMR lines are assigned to [Ni3(ptl)n(PW9O34)2]12- (n=1, 2 or 3; ptl=pyridine-type ligand) on the basis of their [P2Ni3]/[ptl] dependence. The formation constants for γ-picoline complexes at 25 ℃ are K1=80, K2=610, and K3=190 L mol-1. The monopicoline complex has greater affinity for γ-picoline than P2Ni3. A degradation product, [Ni2(WO2)(PW9O34)2]12-, was also identified at low pH by measuring the NMR spectrum of pyridine coordinated to it. The isotropic NMR shifts come mainly from the contact interaction due to σ-electron delocalization.