| Summary: | The various methods of calculating the number and activity of the normal modes of vibration of molecules (and ions) in periodic arrangements are compared. The results are applied to a study of the vibrations of copper-halogen bonds. Among the systems studied are the cupric halides; [CuX4]2-, [Cu2X6]2- and [CuCl5]3- ions; CuX2L2 bridged systems. (X=C1 or Br, L=nitrogen donor ligand.) It is concluded that in the case of systems containing both "normal" (ca. 2.3) and "long" (ca. 3.0) bonds the spectra can be interpreted without the need to take the latter into account. Previous work on the vibrational spectra (below 1000cm-1) of inorganic compounds containing water molecules is reviewed and the inconsistencies and inadequacies pointed out. The study of a variety of aquo-halogenocomplexes reported here is an attempt to make available a systematic basis for future work in this field. Emphasis is laid on compounds containing only one or two molecules of water per complex; these include M2MX5.H2O, M2MX4.2H2O and MX2.2H2O species. For these the librational frequencies of the water molecules lie generally between 350 and 600cm-1. For the monohydrated system a possible means of distinguishing between the rocking and wagging frequencies of the water molecule is proposed. Some other compounds are discussed in which both complexed and lattice water are present; librational frequencies in these can exceed 900cm-1. However, in these cases more data, preferably from single crystals, are required before assignments can be made. Finally the results of a preliminary investigation of some (MX3)n-n chains are included.
|
|---|
