Octahedral metal clusters as molecular building blocks of coordination polymers: Synthesis, characterization, and study of their host-guest interactions

This dissertation work focuses on the use of cyanide-functionalized paramagnetic cluster [(Ta6Cl12i)(CN)12 a]3- with valence electron per cluster (VEC) = 15 as molecular building blocks of coordination polymers. Apical cyanide ligands are used as bridging ligands between the cluster and other molecular building blocks for the preparation of supramolecular assemblies with different dimensions. Using the self-assembly approach, eight new compounds were synthesized and their crystal structures have been determined from sing crystal X-ray diffraction. Two salts [La(DMF)(MeOH)1.5(H2O)0.5Ta 6Cl12(CN)6]•DMF (1) and Sm(H2O) 2(DMF)Ta6Cl12(CN)6(2) were synthesized using the anion [Ta6Cl12(CN)6]3- and solutions of La3+ and Sm3+. Both 1 and 2 precipitated quickly due to extremely low solubility of the products in the solvent system used, thus the products lacked crystallinity. The introduction of bridging ligand 4,4'-dipyridyl N,N'-dioxide (dpdo) enabled the formation of three extended frameworks [Eu(dpdo)(H2O)5(EtOH) 2] [Ta6Cl12(CN)6]•dpdo•H 2O• 4MeOH (3), [Eu(dpdo)3(H2O)4][Ta 6Cl12(CN)6] •5H2O (4) and [Eu(dpdo) 2(H2O)3 Ta6Cl12(CN) 6] •2H2O •0.75EtOH (5), by using the same starting materials but different stoichiometry and solvents.;The compound [Zn2[Ta6Cl12(CN)6 OH] • xH2O containing the Zn2 dimers was synthesized and structurally characterized, but it was difficult to prepare the compound quantitatively for further physical characterization. Two other novel compounds Zn3[Ta6Cl12(CN)4 X2]2 (7) and [Ni(en)2]2[Nb 6Cl12(CN)6] • 2.5MeOH (8) were synthesized and their host-guest molecular interaction were studied. These results illustrate the approach of direct self-assembly is an effective way to prepare metal clusters based coordination polymers with novel structures and properties.