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Whangbo, Myung-Hwan,Lee, Ikchoon 서울대학교 1970 서울대학교 論文集 Vol.21 No.-
IMO 이론을 S_N2 반응에 적용한 결과 작용에너지가 반응의 지표로 사용될 수 있음을 밝혔다. 또한 이차 섭동 항이 무시할 수 없을 정도로 큼을 유도하였다. Intermolecular orbital theory (IMO) is applied to S_N2 reactions. And it is verified that the interactions energies can be used as a reactivity index. In addition, the importance of the second order perturbation is derived in the case of halide exchange reactions of arylmethyl halides.
황보명환,이익춘,Myung-Hwan Whangbo,Ikchoon Lee Korean Chemical Society 1969 대한화학회지 Vol.13 No.4
Maleic Anhydride의 분자궤도를 다음의 파라미터를 사용하여 계산하였다. $h_{o}$=1, $h_{o}$=2, $k_{c=o}$ =0.8 ${\delta}_{{\alpha}_n}=2{\times}(0.3)^n$ 얻어진 분자궤도들로부터 Benzene과 Maleic Anhydride(MA)의 광화학적반응의 작용 에너지를 구하였다. 작용에너지에는 상수항이 포함될 수 있으며 이항이 작용 에너지에 크게 기여함을 보였고 이 반응의 메카니즘은 계산된 작용에너지로 잘 설명됨을 밝혔다. 또한 MA의 두번 째 첨가반응이 광화학적으로 가능하며 MA-Benzene의 부가 생성물은 잘 알려진 입체 화학적 구조를 가져야함을 증명하였다. The MO's of maleic anhydride are calculated using the parameter values, $h_{o}$.= 1, $h_{o}$:= 2, $k_{c=o}$= 1, $k_{c-o}$= 0.8, and ${\delta}_{{\alpha}_n}=2{\times}(0.3)^n$. With these MO's the interaction energies of the photochemical reaction of maleic anhydride (MA) with benzene are calculated using intermolecular orbital theory. It is shown that there are cases where the interaction energy includes a constant term and this term takes a great role in the photochemical interaction energy, and that with the calculated interaction energies the reaction mechanism is quite well explained. And it is proved that the photochemical reaction is possible for the second addition step of MA to benzene, and that the MA-benzene adduct should have the well-known stereochemical structure.
Hyun-Joo Koo*,Myung-Hwan Whangbo* 대한화학회 2007 Bulletin of the Korean Chemical Society Vol.28 No.2
The electronic structures of the new organic conducting salts, the b'- and b''-phases of (BEDT-TTF)2- [(IBr2)0.2(BrICl)0.1(ICl2)0.7], were examined by calculating their electronic band structures, Fermi surfaces and HOMO-HOMO interaction energies using the extended Hckel tight binding method. On the basis of these calculations, we probed why the b'-phase is semiconducting while the b ''-phase is metallic.
Koo, Hyun-Joo,Whangbo, Myung-Hwan American Chemical Society 2014 Inorganic Chemistry Vol.53 No.20
<P>In terms of density functional theory calculations, we explored the reason why the neutron diffraction patterns of a crystalline solid, NaFe<SUB>2</SUB>(H<SUB>3</SUB>O<SUB>2</SUB>)(MoO<SUB>4</SUB>)<SUB>2</SUB>, are explained by invoking the simultaneous presence of two widely different magnetic structures. The partitioning into OH and H<SUB>2</SUB>O groups of the “H<SUB>3</SUB>O<SUB>2</SUB>” units, which interconnect FeO<SUB>4</SUB> chains in each [Fe<SUB>2</SUB>(H<SUB>3</SUB>O<SUB>2</SUB>)(MoO<SUB>4</SUB>)<SUB>2</SUB>]<SUP>−</SUP> layer, leads to various layers different only in their H-atom positions. The crystal structure containing only symmetric FeO<SUB>2</SUB>(HO)(H<SUB>2</SUB>O) chains and that containing only asymmetric FeO<SUB>4</SUB> chains are found to be responsible for the two observed magnetic structures.</P><P>The explanation for the neutron diffraction patterns of a crystalline solid, NaFe<SUB>2</SUB>(H<SUB>3</SUB>O<SUB>2</SUB>)(MoO<SUB>4</SUB>)<SUB>2</SUB>, requires the assumption that two different magnetic structures coexist simultaneously. The cause for this observation was examined.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/inocaj/2014/inocaj.2014.53.issue-20/ic502003j/production/images/medium/ic-2014-02003j_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ic502003j'>ACS Electronic Supporting Info</A></P>
Koo, Hyun-Joo,Whangbo, Myung-Hwan American Chemical Society 2019 Inorganic Chemistry Vol.58 No.21
<P>Two seemingly puzzling observations on two magnetic systems were analyzed. For the oxide-hydrides Sr<SUB>2</SUB>VO<SUB>3</SUB>H, Sr<SUB>3</SUB>V<SUB>2</SUB>O<SUB>5</SUB>H<SUB>2</SUB>, and SrVO<SUB>2</SUB>H, made up of VO<SUB>4</SUB>H<SUB>2</SUB> octahedra, the spin orientations of the V<SUP>3+</SUP> (d<SUP>2</SUP>, <I>S</I> = 1) ions were reported to be different, namely, perpendicular to the H-V-H bond in Sr<SUB>2</SUB>VO<SUB>3</SUB>H but parallel to the H-V-H bond in Sr<SUB>3</SUB>V<SUB>2</SUB>O<SUB>5</SUB>H<SUB>2</SUB> and SrVO<SUB>2</SUB>H, despite that the d-state split patterns of the VO<SUB>4</SUB>H<SUB>2</SUB> octahedra are similar in the three oxide-hydrides. Another puzzling observation is the contrasting magnetic structures of Sr<SUB>2</SUB>CoO<SUB>2</SUB>Cu<SUB>2</SUB>Te<SUB>2</SUB> and Sr<SUB>2</SUB>MnO<SUB>2</SUB>Cu<SUB>1.58</SUB>Te<SUB>2</SUB>, consisting of the layers made up of corner-sharing MO<SUB>4</SUB>Te<SUB>2</SUB> (M = Co, Mn) octahedra. The Co<SUP>2+</SUP> spins in each CoO<SUB>2</SUB>Te<SUB>2</SUB> layer are antiferromagnetically coupled with spins perpendicular to the Te-Co-Te bond, whereas the Mn<SUP>3+</SUP>/Mn<SUP>2+</SUP> ions of each MnO<SUB>2</SUB>Te<SUB>2</SUB> layer are ferromagnetically coupled with spins parallel to the Te-Mn-Te bonds. We investigated the cause for these observations by performing first-principles density functional theory (DFT) calculations for stoichiometric phases Sr<SUB>2</SUB>VO<SUB>3</SUB>H, Sr<SUB>3</SUB>V<SUB>2</SUB>O<SUB>5</SUB>H<SUB>2</SUB>, SrVO<SUB>2</SUB>H, Sr<SUB>2</SUB>CoO<SUB>2</SUB>Cu<SUB>2</SUB>Te<SUB>2</SUB>, and Sr<SUB>2</SUB>MnO<SUB>2</SUB>Cu<SUB>2</SUB>Te<SUB>2</SUB>, as well as nonstoichiometric phase Sr<SUB>2</SUB>MnO<SUB>2</SUB>Cu<SUB>1.5</SUB>Te<SUB>2</SUB>. Our study reveals that the V<SUP>3+</SUP> ions in all three oxide-hydrides should have the spin orientation parallel to the H-V-H bond. The unusual magnetic structure of the MnO<SUB>2</SUB>Te<SUB>2</SUB> layers of Sr<SUB>2</SUB>MnO<SUB>2</SUB>Cu<SUB>1.52</SUB>Te<SUB>2</SUB> arises from the preference of a Mn<SUP>3+</SUP> spin to be parallel to the Te-Mn-Te bond, the ferromagnetic spin exchange between adjacent Mn<SUP>3+</SUP> and Mn<SUP>2+</SUP> ions, and the nearly equal numbers of Mn<SUP>3+</SUP> and Mn<SUP>2+</SUP> ions in each MnO<SUB>2</SUB>Te<SUB>2</SUB> layer. We show that the spin orientation of the magnetic ions in an antiferromagnetically coupled perovskite layer, expected in the absence of nonmagnetic ion vacancies, cannot be altered by the magnetic ions of higher oxidation that result from trace vacancies at the nonmagnetic ion sites.</P><P>We carried out density functional calculations to examine the spin orientations of the V<SUP>3+</SUP> ions in Sr<SUB>2</SUB>VO<SUB>3</SUB>H, Sr<SUB>3</SUB>V<SUB>2</SUB>O<SUB>5</SUB>H<SUB>2</SUB>, and SrVO<SUB>2</SUB>H, as well as the reason why the MnO<SUB>2</SUB>Te<SUB>2</SUB> layers of Sr<SUB>2</SUB>MnO<SUB>2</SUB>Cu<SUB>1.52</SUB>Te<SUB>2</SUB> differ in spin exchange and spin orientation from the CoO<SUB>2</SUB>Te<SUB>2</SUB> layers of Sr<SUB>2</SUB>CoO<SUB>2</SUB>Cu<SUB>2</SUB>Te<SUB>2</SUB>. The spin orientation of the magnetic ions in an antiferromagnetically ordered perovskite layer cannot be altered by the magnetic ions of higher oxidation resulting from trace vacancies of nonmagnetic ions.</P> [FIG OMISSION]</BR>
Koo, Hyun-Joo,WhangBo, Myung-Hwan Korean Chemical Society 2007 Bulletin of the Korean Chemical Society Vol.28 No.2
The electronic structures of the new organic conducting salts, the β'- and β''-phases of (BEDT-TTF)2[(IBr2)0.2(BrICl)0.1(ICl2)0.7], were examined by calculating their electronic band structures, Fermi surfaces and HOMO-HOMO interaction energies using the extended Huckel tight binding method. On the basis of these calculations, we probed why the β'-phase is semiconducting while the β ''-phase is metallic.
Koo, Hyun-Joo,Whangbo, Myung-Hwan American Chemical Society 2014 Inorganic Chemistry Vol.53 No.7
<P>The three isostructural magnetic oxides MAs<SUB>2</SUB>O<SUB>6</SUB> (M = Mn, Co, Ni) containing high-spin M<SUP>2+</SUP> ions undergo a long-range antiferromagnetic ordering below 30 K, but their ordered magnetic structures are not identical. While CoAs<SUB>2</SUB>O<SUB>6</SUB> and NiAs<SUB>2</SUB>O<SUB>6</SUB> adopt the commensurate superstructure of <I>q</I><SUB>1</SUB> = (0, 0, 1/2), MnAs<SUB>2</SUB>O<SUB>6</SUB> has the incommensurate superstructure of <I>q</I><SUB>2</SUB> = (0.055, 0.389, 0.136). The cause for this difference was examined by calculating their spin exchange and magnetic dipole–dipole interaction energies. In CoAs<SUB>2</SUB>O<SUB>6</SUB> and NiAs<SUB>2</SUB>O<SUB>6</SUB>, the strongest M–O···O–M spin exchange, <I>J</I><SUB>1</SUB>, dominates over other exchanges, hence leading to the <I>q</I><SUB>1</SUB> superstructure. For MnAs<SUB>2</SUB>O<SUB>6</SUB>, the spin exchanges are not a deciding factor leading to its magnetic superstructure, being all weak and comparable in strengths, but the magnetic dipole–dipole interactions are.</P><P>CoAs<SUB>2</SUB>O<SUB>6</SUB> and NiAs<SUB>2</SUB>O<SUB>6</SUB> adopt the (0, 0, 1/2) magnetic superstructure because the M−O···O−M spin exchange <I>J</I><SUB>1</SUB> dominates over the other spin exchanges. For the incommensurate superstructure (0.055, 0.389, 0.136) found for MnAs<SUB>2</SUB>O<SUB>6</SUB>, the spin exchanges are not a deciding factor, but the magnetic dipole−dipole interactions are.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/inocaj/2014/inocaj.2014.53.issue-7/ic500156e/production/images/medium/ic-2014-00156e_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ic500156e'>ACS Electronic Supporting Info</A></P>
Lee, Changhoon,Hong, Jisook,Whangbo, Myung-Hwan,Shim, Ji Hoon American Chemical Society 2013 Chemistry of materials Vol.25 No.18
<P>We explored how to improve the thermoelectric properties of the layered transition-metal dichalcogenides 2H-MQ<SUB>2</SUB> (M = Mo, W; Q = S, Se, Te) by comparing the thermoelectric properties of hypothetical mixed-layer systems 2H-MQ<SUB>2</SUB>/2H-MQ′<SUB>2</SUB>, in which two different layers 2H-MQ<SUB>2</SUB> and 2H-MQ′<SUB>2</SUB> (Q, Q′ = S, Se, Te) alternate, with those of their pure components on the basis of density functional calculations. Our study predicts that the mixed-layer compounds MS<SUB>2</SUB>/MTe<SUB>2</SUB> (M = Mo, W) strongly enhance the thermoelectric properties as a consequence of reducing the band gap and the interlayer van der Waals interactions. The layer-mixing is predicted to be a promising way of improving the thermoelectric properties of 2H-MQ<SUB>2</SUB>.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2013/cmatex.2013.25.issue-18/cm402281n/production/images/medium/cm-2013-02281n_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm402281n'>ACS Electronic Supporting Info</A></P>
Reiff, William M.,Schulz, Charles E.,Whangbo, Myung-Hwan,Seo, Jung In,Lee, Yoon Sup,Potratz, Gregory R.,Spicer, Charles W.,Girolami, Gregory S. American Chemical Society 2009 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.131 No.2
<P>Mossbauer, EPR, magnetic susceptibility, and DFT studies of the unusual two-coordinate iron(II) amide Fe[N(t-Bu)(2)](2) show that it retains a linear N-Fe-N framework due to the nonbonding delta nature of the (xy, x(2)-y(2)) orbitals. The resulting near-degenerate ground state gives rise to a large magnetic moment and a remarkably large internal hyperfine field. The results confirm that extraordinary orbital magnetic effects can arise in linear transition metal complexes in which orbital degeneracies are not broken by Jahn-Teller or Renner-Teller distortions.</P>
이본수,황보명환,이익춘,Lee Bon-su,Whangbo Myung Hwan,Lee Ik Choon Korean Chemical Society 1969 대한화학회지 Vol.13 No.2
전보에 이어 90% 에탄올 용액에서의 염화 벤질 및 브롬화 벤질과 요오드화 이온 간의 교환반응을 연구하였다. HSAB이론을 도입하여 할로겐화 이온의 pb혼합 궤도가 서로 겹치는 전이 상태로서 실험 결과를 설명하였다.