First Row Transition Metal Complexes of Heptadentate N7 Donor Ligands
Three heptadentate N7 ligands have been studied in this thesis: N, N’-bis(2,2’-bipyridin-6-ylmethyl)pyridine-2,6-dimethylamine (bmpy), N, N’-bis(2,2’-bipyridin-6-ylmethyl)diethylamine-1,2-dimethylamine (bmdet) and N, N’-bis(6-methyl-2,2’-bipyridin-6’-ylmethyl)diethylamine-1,2-dimethylamine (DMbmdet). Bmpy is a new ligand while bmdet and DMbmdet were first prepared by a previous group member and their successful purification by column chromatography from their degraded products was achieved.
The coordination behaviours of these ligands towards first row transition metals (Co, Cu, Fe, Ni, Zn) was studied. Despite many attempts, X-ray quality crystals could not be obtained for any of the complexes studied. Therefore, their solution-phase identities were investigated directly by ESI-MS. The mole ratio between the five metal ions and all three ligands is shown largely not to influence the nature of the complexes formed; in nearly all cases, mononuclear species are predominantly formed regardless of the M:L mole ration. Exceptions are the nickel / DMbmdet system, which exhibited a tendency to form dimeric species as the concentration of Ni2+ ions was increased, while the Cu2+ / bmpy system gives rise to a dimeric complex as the main product.