Raman scattering study of pressure effects on the structure and the coordinationhyphen;induced charge redistribution in 4hyphen;cyanopyridine@fa@f)

摘要

The Raman spectra in the frequency regions of the lattice and the internal modes of the crystalline CNPy and Zn(CNPy)2Cl2have been measured at various pressures up to 16.5 and 20 kbar, respectively. A structural phase transition at 10 kbar in CNPy and two at 8.2 and 18 kbar in Zn(CNPy)2Cl2were observed. At high pressure, CNPy suffers a lattice distortion along the eigenvector of a soft phonon, and Zn(CNPy)2Cl2undergoes a molecular configuration distortion which leads to the softening of a rotational phonon. The charge distribution on the CNPy molecule is changed by coordination and also by external pressure and this charge redistribution has been correlated with the vibrational spectral changes.