UBC Theses and Dissertations
Oxovanadium(IV) and (V) complexes with naturally-occurring molecules Zhou, Ying
Complexes with naturally-occurring ligating moieties were prepared and studied aspart of an overall process to understand the coordination chemistry of vanadium. Bis(kojato) oxovanadium(IV), VO(ka)2, bis(3-oxy-1,2-dimethy1-4-pyridinonato)-oxovanadium(IV), VO(dpp)2, bis(2-hydroxymethy1-5-oxy-1-methy1-4-pyridinonato)-oxovanadium(IV), VO(hmp)2, bis[2-(2'-oxypheny1)-2-oxazolinato]oxovanadium(IV),VO(oz)2, bis[2-(2'-oxypheny1)-2-thiazolinato]oxovanadium(IV), VO(thz)2.0.5H20 and bis(benzohydroxamato) oxovanadium(IV), VO(bz)2 were prepared and characterized. In addition, two oxovanadium(V) complexes, bis(benzohydroxamato) methoxo-oxovanadium(V), V0(OCH3)(bz)2 and bis(benzohydroxamato) ethoxooxovanadium(V), VO(0C2H5)(bz)2 were also prepared from VO(bz)2. All eight complexes were prepared in one step processes, in particular V0(dpp)2 and V0(hmp)2 which were prepared directly from maltol and kojic acid, respectively, using vanadyl and methylamine in a one-potsynthesis method. All oxovanadium complexes were characterized by infrared spectroscopy, mass spectrometry, elemental analyses and room temperature magnetic susceptibility measurements, and whenever possible, by UV-Visible spectrophotometry. 1H and 51VNMR were also used to characterize the two oxovanadium(V) complexes,VO(OCH3)(bz)2 and VO(0C2H5)(bz)2. Single crystal X-ray diffraction studies ofVO(oz)2 and V0(thz)2 were also performed by the departmental facility. Characterization of the oxovanadium(IV) complexes revealed them to be 5-coordinate square pyramidal bis(ligand) oxovanadium(IV) complexes with each ligand binding in a bidentate fashion to the central vanadium atom. VO(OCH3)(bz)2 and V0(0C2H5)(bz)2 were found to be 6-coordinate bis(ligand) oxovanadium(V) complexes. Comparison of the infrared stretching frequencies of the vanadium-oxo bond revealed that the strength of the vanadium-oxo bond in the eight complexes was consistent with bond strength observed in other oxovanadium complexes. Single crystal X-ray diffraction studies of VO(0z)2 and VO(thz)2 showed them to be isostructural. The bidentate ligands are bonded to the vanadium center through the phenolate oxygen and the oxazoline orthiazoline ring nitrogen. The two complexes are both regular square pyramids with the bidentate ligands coordinated in a trans fashion. The vanadium atoms in these complexes are elevated by approximately 0.6 A from the basal square planes defined by the four ligand 0 and N donors. The average V=0 bond length is 1.6 A.
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