Polynuclear magnetic complexes of manganese(II), cobalt(II), nickel(II) and copper(II)

This thesis deals with rational design and syntheses of novel magnetic complexes with extended structures by using molecular building block methodology. Several novel polynuclear complexes containing first-row transition-metal ions such as, MnII, CoII Cu II, and NiII were synthesized from the self-assembly of functional molecular building blocks. Intermolecular interactions such as hydrogen bonds or metal-ligand coordination bonds have been used to link the molecular building blocks into higher dimensional supramolecular architectures.; The magnetic properties were incorporated into the molecular building blocks by the choice of bridging ligands. The doubly deprotonated tetraacetylethane (tae) bridging ligand, which has two perpendicular coordinating planes, was used to produce dinuclear and tetranuclear molecular building units containing CuII, CoII, and NiII centers. The magnetic exchanges promoted by the tae ligand are complicated and were found to be dependent on the metal center. The ∼90 degree twist of the tae ligand was also used to produce helical and chiral structures in dinuclear and tetranuclear building units containing octahedral metal centers. The resulting building blocks were then linked together either by complementary hydrogen-bonds or metal-ligand coordination bonds to produce extended structures with interesting structural related properties, such as chiral channels and cavities. Chloride bridged transition metal containing -M₂(μ-Cl)₂- units have also been studied to produce extended structures through hydrogen bonding or metal-ligand coordination bonding. Specifically, a one-dimensional soluble coordination polymer was obtained with the neutral 2,2′-thiodiethanol ligand as spacers to link -M₂(μ-Cl)₂- building units. Another spacer, 4,4′-bipyridine, was also used to link molecular building blocks through metal-ligand coordination bonding. One- and two-dimensional CuII and CoII coordination polymers were obtained with 4,4′-bipyridine spacers. The magnetic and zeolite-like properties of the resulting polymeric complexes were studied.