The effect of substituents on the coordination of nitrogen-containing ligands
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
A wide range of complexes of divalent and trivalent iron, ruthenium and osmium containing coordinated 2.2'-bipyridine have been prepared. These are all six coordinate and are of general formulae (M(bipy)₃)N+, (M(bipy) ₂x₂)N+, (M(bipy)₂XY)N+ (M(bipy)X₄)N+, (M(htpy)X ₂Y₂)N+, where X and Y include a wide range of monodentate and bidentate ligands including cyanide, oxalate, ammonia, pyridine and the halogens. Several complexes containing 4,4'-dimethylbipyridine have also been prepared. The electronic absorption spectra of these complexes in solution have been measured, and a number of assignments made for the observed transitions. Both the divalent and the trivalent complexes show intense intraligand transitions of hipyridyl in the ultraviolet region. In the visible region, the divalent complexes show intense metal to ligand charge transfer transitions, while the trivalent complexes exhibit ligand to metal charge transfer transitions of different types. The effects of such factors as the metal ion, the charge on the metal ion, substituents in the bipyridyl ligand and the presence of coordinated ligands other than bipyridyl have been discussed, and the results of this work related to earlier studies. Proton magnetic resonance spectra of some divalent complexes containing 4,4'-dimethylbipyridine have been measured and these are correlated with the electronic absorption spectra where possible.