• Korean Journal of Crystallography
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• v.6 no.2
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• pp.75-79
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• 1995

The crystal structure of Tris(ethylenediamine)nickel(II)Chromate has been determined by X-ray crystallography. Crystal data : a=9.027(2)Å, c=9.751(5)Å이며, Z=2, V=687.9(2)Å3, Dc=1.714gcm-3, μ=21.635-1. The intensity were collected with Mo-Kα radiation (λ=0.7107Å) on an automatic four-circle diffractometer with a graphite monochromator. The structure was solved by Patterson method and refined by full matrix least-square methods using unit weights. The final R and S values were R=0.029, Rw=032, Rall=0.049 andS=0.018 for 342 observed reflections. The chromate ions are located at position of point of point symmetry 32 and their oxygens are sixfold disodered in an unusual way. Extensive strong hydrogen bonds between complex cations and chromatic anions are found in axial and equatorial directions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.645-646
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• 2005

The increasing hydroxyl ($OH^-$) groups diffused into the TEOS and then weakened reactants such as H-C-O-Si bonds on the surface of TEOS film were actively generated with the increase of slurry temperature. These soft reactants on the surface of TEOS film could be removed easily by mechanical parts of CMP.

• Bulletin of the Korean Chemical Society
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• v.16 no.11
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• pp.1109-1112
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• 1995

Bis(silyl)alkylbenzenes such as bis(1-sila-sec-butyl)benzene (1) and 2-phenyl-1,3-disilapropane (2) were prepared in high yields by reduction of the corresponding chlorosilanes with LiAlH4. The dehydropolymerization of 1 and 2 was carried out with group 4 metallocene complexes generated in situ from Cp2MCl2/Red-Al and Cp2MCl2/n-BuLi (M=Ti, Hf), producing two phases of polymers. The TGA residue yields of the insoluble polymers were in the range of 64-74%. The molecular weights of the soluble polymers produced ranged from 700 to 5000 (Mw vs polystyrene) and from 500 to 900 (Mn vs polystyrene). The dehydropolymerization of 1 and 2 seemed to initially produce a low-molecular-weight polymer, which then underwent an extensive cross-linking reaction of backbone Si-H bonds, leading to an insoluble polymer.

• Archives of Pharmacal Research
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• v.12 no.1
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• pp.52-57
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• 1989

The structure of cinmetacin was determined by single crystal X-ray diffraction analysis. The compound was recrystallized from a mixture of acetone and water in orthorhombic, space group $P2_12_12_1$, with Z=4, a=35.681(8), b=9.482(2), c:5.071(1) ${\AA}$, $D_x=1.352 g/cm^3$, and $D_m=1.35g/cm^3$. The structure was solved by direct method and refined by least-squares procedure to the final R value of 0.036 for 1441 observed reflections ($F{\geq}3{\sigma}(F)$). The carboxyl group of the molecule is nearly perpendicular to the indole ring. The dihedral angle between indole ring and phenyl group is $64.5^{\circ}$. The molecules are linked together via O(1)-H ----O(3) hydrogen bonds, and arranged along 2-fold screw axis in the crystal. The intermolecular contacts are the normal van der Waals' forces.

• Archives of Pharmacal Research
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• v.11 no.2
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• pp.127-133
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• 1988

The crystal structure of fenbufen was determined by X-ray diffraction techniuques. The compound was recrystallized in orthorhombic crystal system, space group $Pca2_1$ a = 31. 918(10), b = 5.550 (2), c = 15.078 (9) ${\AA}, D_m$= $1.26, {\D_x$= 1.264 g/$\textrm{cm}^3$, and Z = 8. The structure was solved by direct methods and refined by least squares procedure to the final R value of 0.051 for 1780 independent reflections. Two molecules in the asymmetric unit are related by a pseudo center of symmetry and dimerized via O-H...O hydrogen bonds. The carbonyl group attached to the phenyl ring is nearly coplanar to the ring. In the crystal the molecules are arranged in paralle stacks in the a direction.

• Bulletin of the Korean Chemical Society
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• v.10 no.3
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• pp.247-250
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• 1989

The molecular structure of cyclobutylmethyl ketone (c-$C_4H_7COCH_3$) has been investigated by molecular mechanics II (MM2). For the monosubstituted cyclobutane there are two possible ring conformations, the equatorial and axial form, but for the cyclobutylmethyl ketone the equatorial form is predominant conformation. For the $COCH_3$ moiety there are two stable orientations which are the equatorial-gauche and the equatorial-trans form. The equatorial-gauche form where the C = O bond is nearly eclipsing (torsional angle ${\angle}C4-C3-C2-O10=14.5^{\circ}$) one of the ${\alpha}$C-C bonds of the four-membered ring was preferred conformer with steric energy of 13.37 kcal/mol. The equatorial-trans form where the C = O bond is nearly eclipsing (${\angle}C4-C3-C2-O10=145.0^{\circ}$) the ${\alpha}$ C-H bond of the four-membered ring was less stable conformer with steric energy of 15.40 kcal/mol.

• International Journal of Advanced Culture Technology
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• v.11 no.2
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• pp.323-329
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• 2023

In this study, Proline pentamer model was used to investigate change in the dihedral angle, intramolecular hydrogen bonding and formation energies during structural optimization. L-Proline (LP, as an imino acid residue) pentamers having four conformation types [β: φ/ψ=t−/t+, α: φ/ψ=g−/g−, PP_II: φ/ψ=g−/t+ and Plike: φ/ψ= g−/g+] were carried out by QCC [B3LYP/6-31G(d,p)]. The optimized structure and formation energy were examined for designated structure. In LP, P-like and PP_II types did not change by optimization, and β types were transformed into PP_II having no H-bond independently of the designated ψ values. PP_II was more stable than P-like by about 2.2 kcal/mol/mu. The hydrogen bond distances of d2(4-6) type H-bonds were 1.94 - 2.00Å. In order to understand the processes of the transformations, the changes of φ/ψ, distances of NH-OC (d_NH/CO) and formation energies (ΔE, kcal/mol/mu) were examined.

• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.104-111
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• 2001

B-doped hydrogenated amorphous silicon carbide (a-SiC:H) thin films were prepared by plasma-enhanced chemical-vapor deposition in a gas mixture of $SiH_4, CH_4,\;and\; B_2H_6$. Physical and chemical properties of a-SiC:H films grown with varing the ratio of $B_2H_6/(SiH_4+CH_4)$ were characterized with various analysis methods including scanning electron microscopy (SEM), X-ray diffractometry (XRD), Raman spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, secondary ion mass spectroscopy (SIMS), UV absorption CH_4spectroscopy and electrical conductivity measurements. With the B-doping concentration, the doping efficiency and the micro-crystallinity were decreased and the film became amorphous when $B_2H_6/(SiH_4{plus}CH_4)$ was over $5{\times}10^{-3}$. The addition of $B_2H_6$ gas during deposition decreased the H content in the film by lowering the quantity of Si-C-H bonds. Consequently, the optical band gap and the activation energy of a-SiC:H films were decreased with increasing the B-doping level.

• Journal of the Korean Chemical Society
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• v.25 no.6
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• pp.343-350
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• 1981

The crystal and molecular structure of P-aminobenzaldehyde cyclohexylthiosemicarbazone, C14H20N4S, has been determined from 2712 integrated intensities measured on a computer controlled four circle diffractometer with monochromated $CuK_{\alpha}$, X-ray radiation. The crystals are monoclinic, space group C2/c with eight molecules in a unit cell of dimensions, a = 12.488(2), b = 12.276(4), c = 19.997(6)${\AA}$ and ${\beta}=103.55(3)^{\circ}$. The structure was solved by Patterson and Fourier method and refined by a full-matrix least squares method to a final R value of 0.058 for all reflections. The C(8)-S bond is trans to N(2)-N(3) and C(8)-N(1) is cis to N(2)-N(3) bond. The cyclohexane ring has chair conformation and makes an angle of $40.7^{\circ}$ with the benzene ring. The molecules are linked by N(2)H…S hydrogen bonds into dimer-like units which are held together by $N-H{\ldots}N$ hydrogen bonds. Sulfur accepts second rather weak hydrogen bond from N(4). An intramolecular hydrogen bond exists between N(1) and N(3) atoms.

• Bulletin of the Korean Chemical Society
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• v.29 no.6
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• pp.1195-1198
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• 2008

Kinetic studies of the additions of benzylamines to a noncyclic dicarbonyl group activated olefin, methyl $\alpha$-acetyl-$\beta$ -phenylacrylates (MAP), in acetonitrile at 30.0 ${^{\circ}C}$ are reported. The rates are lower than those for the cyclic dicarbonyl group activated olefins. The addition occurs in a single step with concurrent formation of the $C_\alpha$ -N and $C_\beta$ -H bonds through a four-center hydrogen bonded transition state. The kinetic isotope effects ($k_H/k_D$ > 1.0) measured with deuterated benzylamines ($XC_6H_4CH_2ND_2$) increase with a stronger electron acceptor substituent ($\delta\sigma$ X > 0) which is the same trend as those found for other dicarbonyl group activated series (1-4). The sign and magnitude of the cross-interaction constant, ρXY, is comparable to those for the normal bond formation processes in the $S_N2$ and addition reactions. The relatively low ${\Delta}H^\neq$ and large negative ${\Delta}S^\neq$ values are also consistent with the mechanism proposed.