Experimental and calculated vibrational spectra and structure of Ziegler-Natta catalyst precursor:: 50/1 comilled MgCl2-TiCl4

The vibrational Infrared and Raman Spectra of a MgCl2-TiCl4 Ziegler-Natta catalyst precursor with a 50/1 MgCl2/TiCl4 ratio have been recorded. The Raman spectrum of this catalyst precursor, in the range 50-500 cm(-1), shows clear scattering lines which can be assigned to the complex MgCl2-TiCl4, well separated from those of the initial species. Analogous, but less clear signals can be found in the infrared spectrum. Vibrational symmetry analysis and quantum chemical calculations of suitable models of MgCl2-TiCl4 complex have been made for the interpretation of the experimentally recorded spectra. The observed spectroscopic signals can be explained in terms of the existence of only one type of MgCl2-TiCl4 complex where the TiCl4 molecules are complexed on the MgCl2 along the (110) lateral cuts in a local C-2v symmetry with the Ti atoms in an octahedral coordination.