| Popis: |
Two kinds of solids were obtained for Sc(PMBP)3 by precipitation from different solvents. They were light-yellow crystal and yellowish-white powder, and their melting points were 209 and 217 °C, respectively. Raman spectra of six anhydrous samples prepared from these materials were measured and classified into two types of spectral patterns. Raman solute spectra of these two materials were measured in a dilute solution of dichloromethane, in which the solute is a free molecule in a solvent cage. Their spectra were considerably similar to each other, but they indicated clear differences in some pairs of bands. One of these two molecules was concluded to be a facial form of Sc(PMBP)3, because the other constituent has been established to be a meridional form of Sc(PMBP)3 by X-ray analysis of a single crystal. Structural optimization for mer- and fac-Sc(PMBP)3 and their vibrational calculation of frequencies and intensities were carried out with the density functional method of B3LYP/6-31G**. Their computed Raman spectra were well coincident with their observed spectra. The existence of fac-Sc(PMBP)3 has been established by thermal analysis, Raman spectroscopy and ab initio calculation. |
Full Text from ScienceDirect