The solubility of YbCl3·3H2O-18-C-6-CH3COCH3 systemat 25℃ was inestigated by a seminicro method of phase equilibrium study. The refractive indexes of the saturated solutions were determined. The solubility diagram and refractive index curve of saturated solutions were constructed. The behavior of water in this system during the equilibrium was examined. The results indicated that there were two new complexes formed in this system at 25℃, namely 2YbCl3·18-C-6· 6H2O·CH3COCH3(1) and YbCl3·18-C- 6·3H2O·0.5CH3COCH3(2). Both were of incongruenty in acetone. The influences of salt anions and solvents on formation of complexes were studied. Based on phase equilibrium data, the solid complexes were prepared. Their compositions and properties were investigated by IR spectroscopy, DTG- TG, DSC, as well as chemical and elemental analyse. The coordination structures were predicted for the solid complexes YbCl3·18-C-6·3H2O and YbCl3·18-C-6.

Key words: YTTERBIUM CHLORIDE, CROWN ETHER, PHASE EQUILIBRIUM, CHEMICAL ANALYSIS, ELEMENTAL ANALYSIS, INFRARED SPECTROPHOTOMETRY, THERMOGRAVIMETRY