Syntheses, structures and magnetic properties of compounds containing linked, multiply-bonded dimetal units /.
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1993.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy ProQuest, Abstract |
| Abstract: | The tetranuclear compounds [{M2(chp)4}(pyz)](BF4)2 (M = Ru, Os) and the dinuclear compounds [M2(chp)4(py)](BF4) (M = Ru, Os) have been synthesized and characterized by X-ray crystallography and by magnetic susceptibility measurements. The pyrazine ligand bridges two diruthenium or diosmium species in the [{M2(chp)4}(pyz)][^2+] (M = Ru, Os) cation, and the pyridine ligand coordinates to one axial position in the [M2(chp)4(py)]+ (M = Ru, Os) ion. There is no significant magnetic exchange interaction between the two dinuclear species in the [{Ru2(chp)4}(pyz)][^2+] ion, and the decrease in moment at low temperatures results primarily from zero-field splitting effects. The tetranuclear and dinuclear osmium complexes show very different behavior from ruthenium complexes. The dinuclear osmium complex, [Os2(chp)4(py)](BF4), shows a spin-orbit coupling at room temperature and Curie-Weiss behavior in overall magnetic data. However, the tetranuclear osmium complex does not show a spin-orbit coupling and display that three unpaired electrons present per diosmium unit at room temperature. The polymeric [Ru2(O2CC2H5)4(phz)](BF4) has been obtained and characterized by X-ray crystallography and by magnetic susceptibility measurements. The phenazine ligands connect the dinuclear species into kinked chains. The compound is antiferromagnetic with a magnetic moment of ca. 4.3 μ[B] at 300 K that tends toward zero as 0 K is approached (1.72 μ[B] at 2.7 K). The linear-chain compound Ru2(O2CCMePh2)4Cl has been prepared and characterized by X-ray crystallography and by magnetic susceptibility measurements. The chloride ligands bridge the dinuclear units into linear chains. There is an antiferromagnetic interaction between dinuclear units with J (coupling constant) of -10.9 cm^-1. The two dimensional complex, 2Rh2(O2CCF3)4*TCNE has been synthesized and structurally characterized. The TCNE ligands bridge four Rh2 units and extend to the two-dimensional layer. Each layer is separated by about 10A along the c axis. The benzene molecules occupy the cavities between the layers. The THF solution of 2Th2(O2CCF3)4*TCNE gave the compound, Rh2(O2CCF3)4(THF)2 which indicates that electron-donating solvent molecules can break the bonding between Rh and the TCNE bridging ligand. |
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| Item Description: | "Major subject: Chemistry." Vita. |
| Physical Description: | xiv, 139 leaves : illustrations ; 28 cm |
| Bibliography: | Includes bibliographical references. |