• Bulletin of the Korean Chemical Society
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• v.9 no.6
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• pp.365-368
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• 1988

Coordination chemistry of organotin(IV) dithiocarbamate complexes has been examined in terms of far infrared and $^{119}Sn$-NMR spectroscopies. Although the Sn-S stretching vibrational bands of the complex could not be correlated with the bonding nature of the dithiocarbamate ligand, $^{119}Sn$ chemical shifts were sensitive enough to distinguish clearly the coordination number of tin, and as such the bonding mode of the dithiocarbamate ligand could be indentified to be monodentate or bidentate. Thus the $^{119}Sn$-NMR study on new cyclohexyltin(IV) dithiocarbamate complexes along with the known complexes suggests that the bonding mode of the dithiocarbamate ligands and the consequent coordination number of tin are determined mainly by the inductive effects of the organic groups attached to the tin atom.

• Bulletin of the Korean Chemical Society
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• v.26 no.6
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• pp.892-898
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• 2005

A long, bis(monodentate), linking Schiff-base ligand L (py-CH=N-$C_6H_4$-N=CH-py) was prepared from 1,4-phenylenediamine and 3-pyridinecarboxaldehyde by the Schiff-base condensation. Ligand L has two terminal pyridyl groups capable of coordinating to metals through their nitrogen atoms. In contrast, the same reaction between 1,2-phenylenediamine and 3-pyridinecarboxaldehyde produced a mixture of imidazol isomers (2-pyridin-3-yl-1H-benzoimidazole), which are connected to one another by the N-H…N hydrogen bonding to form a tetramer. From Zn($NO_3)_2{\cdot}6H_2O$ and ligand L under various conditions, one discrete molecule, trans- [Zn($H_2O)_4L_2]{\cdot}(NO_3)_2{\cdot}(MeOH)_2$, and two 1-D zinc polymers, [Zn$(NO_3)(H_2O)_2(L)]{\cdot}(NO_3){\cdot}(H_2O)_2$ and [Zn(L) (OBC)($H_2O$)], were prepared. In ligand L, the N$\ldots$N separation between the terminal pyridyl groups is 13.994 $\AA$, with their nitrogen atoms at the meta positions (3,3’) in a trans manner. The corresponding N$\ldots$N separations in its compounds range from 13.853 to 14.754 $\AA$.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.2
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• pp.107-112
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• 1996

To clarify the mechanism of silica adsorption to soil, kinetic study using continuous stirred-flow method was conducted with the Luisiana soil at three pH levels (pH 5.0, 6.5, and 8.0). Silica adsorption increased continuously without showing the maximum adsorption for long enough experimental time. Kinetic curve of silica adsorption could be divided into two stage processes. The first stage process was fitted well to the following equation with highly significant correlation coefficient : $$R_{ad}=K_a*(Q_{OH}^S)^n$$ where, $R_{ad}$ is silica adsorption rate($Si\;{\mu}mal/min$). $Q_{OH}^S$ is the negative charge sites on the soil surface created by alkali titration, and $K_a$ and n are constants. The "n" value of the first stage process was 1.1. This value indicates that the silica adsorption is accomplished by the monodendate ligand bonding. The second stage process was fitted well to the following equation : $$R_{ad}=K_b*(pH)$$ where, $K_b$ is a constant. The equation indicates that the silica adsorption is not proportional to the $OH^-$ ion concentration. Rather, the increasing pattern of silica adsorption rate with the increase of $OH^-$ ion concentration would decrease exponentially.