The vibrational spectra and normal coordinate analysis of some halides and oxy-halides.

An Algol computer program for the calculation of force constants from vibrational frequencies has been written. Some improvements to the standard method by which force constants are refined to fit vibrational data have been made. The vibrational spectra of some oxy-halides of the types MOX4, MOX3, and MO2X2 have been recorded; some calculations have been made on the MOX4 molecules, the results of which add weight to the proposed assignments. Some conclusions concerning the structures of the MO2X2 type compounds are drawn. Infrared and Raman data have been obtained for a number of bridged halides (planar and non-planar). Calculations have been made on these systems; the main conclusion is that for non-planar systems, the bridge force constant is about 45% of that of the terminal constant. In the case of the planar system studied, the bridge force constant was found to be significantly higher (relatively) than in the non-planar case.