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Abstract

The structures of the NO3 group have been discussed and the vibrational spectra that may be expected to result from these structures. The various spectral criteria suggested to differentiate between these structures have been reviewed and the experimental problems in obtaining these spectra have been outlined.

The series of compounds M(N03)2 (H20)4, M(N03)2(H20)4, M(N03) where M= Mn(II), Co(II), Ni(II) have been prepared by dehydration techniques and characterised by analysis, infra-red and electronic spectral measurements and magnetic susceptibility determinations. The infra-red spectra have been examined in detail in the 3600-200CM-1 range and related to the structures of the compounds where these a.re known. The spectra are discussed in relation to the structural criteria found in the literature. It is suggested that the near infra-red re ion (3600-500 cm-1) can only indicate that the N03 group is co-ordinated and give some indication of the strength of the metal-nitrato interaction. The far infra-red region (500-200cm-1) can give information about the environment of the metal atom and hence can indicate the mode of nitrato co-ordination from the number of bands observed, their positions and their shapes. This is probably seen clearly only when oxygen atoms are bonded to the metal, and not so clearly when N-bonded or S-bonded ligands are present. Chloro compounds could probably be fruitfully examined also, as the metal-chlorine bond usually has a higher force constant than the metal-oxygen bond.

It is felt that polarised Raman studies of single crystals, related to the crystal symmetry of the compound is the best method of obtaining clear information about the vibrational frequencies of nitrato compounds.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science > QD Chemistry
Departments:	School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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