Text

theses

ETD doctoral

The synthesis of novel actinide coordination complexes and polymetallic actinide clusters with chalcogen based anions is the focus of this thesis. Thorium and uranium compounds with bidentate ligands have been prepared via in situ oxidation of Th or U with various ligands that include I2, PhEEPh, C6F5EEC6F5 (E = S, Se), and pySSpy. Four compounds, (bipy)2Th(SeC6F5)4, (py)Th(Spy)4, (py)U(Spy)4, and (py)2UI2(Spy)2 were isolated in good yield and characterized by X-ray diffraction. Two bimetallic compounds, py4Th2I2(Spy)2(Se2)2 and py7Th2F5(SC6F5)3 were synthesized from the reaction of heteroleptic intermediates “Th(EPh)x(SR)4-x” (E = S, Se; R = C6F5, py) with elemental selenium and silver(I) fluoride respectively. The first two pyridinethiolate compounds of thorium have been synthesized and discussed in this chapter. Actinide chalcogenolate clusters supported by fluorinated ligands is also discussed.

Tetrametallic thorium clusters with a distorted Th4E4 (E = S, Se) cube-like core are prepared by ligand based redox reduction of elemental E with heteroleptic thorium intermediates “Th(EPh)x(E’C6F5)4-x” and oxidation of EPh- to PhEEPh. Four compounds, (py)8Th4(μ3-S)4(μ2-SPh)4(SC6F5)4, (py)8Th4(μ3-Se)4(μ2-SePh)4(SeC6F5)4, (py)8Th4(μ3-S)4(μ2-SPh)4(SeC6F5)4, and (py)8Th4(μ3-Se)4(μ2-SePh)4(SC6F5)4 were isolated and characterized by NMR spectroscopy and X-ray diffraction. Heterochalcogen clusters could only be isolated when μ3-E = μ2-E(Ph) in the core. These compounds show the impact of ring fluorination, with less nucleophilic EC6F5 ligands only occupying terminal binding sites, and this reads as the terminal binding sites effect uniform crystal packing and intermolecular π…π and H-bonding interactions throughout each compound. 77Se NMR spectroscopy reveals the solid-state structure of the tetrametallic clusters are maintained in solution.

Tetrametallic uranium clusters with distorted U4E4 (E = S, Se) cube-like core are prepared similarly to the thorium tetrametallic clusters. Four compounds, (py)8U4(μ3-S)4(μ2-SPh)4(SC6F5)4, (py)8U4(μ3-Se)4(μ2-SePh)4(SeC6F5)4, (py)8U4(μ3-S)4(μ2-SPh)4(SeC6F5)4, and (py)8U4(μ3-Se)4(μ2-SePh)4(SC6F5)4 were isolated and characterized by X-ray diffraction and magnetic susceptibility measurements. These compounds show similar reactivity where isolatable compounds form only when μ3-E = μ2-E(Ph) in the core. The tetrameric uranium core with four μ3-E bridging ligands offers a unique look at magnetic susceptibility studies, as reports on U(IV)-E-U(IV) environments are limited to mono- and bimetallic compounds. Magnetic susceptibility studies suggest antiferromagnetic coupling at low temperatures.

ETD_11349

Ph.D.

Includes bibliographical references

doi:10.7282/t3-hhxp-5e90

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