X-ray crystallographic studies of sulfur/selenium heteroatom compounds
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The major aim of research reported on this thesis uses X-ray crystallography to investigate the structural features of a series of pentafluorosulfuranyl (SF₅) containing aromatic compounds, chalcogen amides, 2,4-diaryl-1,3-selenazoles and 2,4-diaryl-1,3-chalcogen azoles bearing SF₅ group and organo phosphorus-chalcogen macrocycles incorporationg double OP(S)SC[sub]n or OP(Se)SeC[sub]n scaffolds. The basic theory of crystallography is introduced in Chapter 1, followed by a general discussion on pentafluorosulfuranyl (SF₅) containing heteroatom compounds and sulfur/selenium heterocycles in Chapter 2. Ten pentafluorosulfuranyl (SF₅)-containing aromatic compounds have been studied crystallographically in Chapter 3. All S-F bond lengths in these compounds are very similar [1.571(3) to 1.618(3) Å and 178.5(3) to 180.0° for the C-S-F(ax) bond] and the angles of two adjacent F(eq) is approximate to 90°. The intramolecular C[sub](aryl)-H···F(eq) and intermolecular C[sub](aryl)-H···O/N/F/Cl interactions, and π-stacking interactions are observed in the packing frameworks. X-ray crystal structure analysis reveals that in the structures of 2,4-diaryl-1,3-selenazoles in Chapter 4, the five-membered N-C-Se-C-C rings have either planar or near-planar conformations, and exhibit a series of the intramolecular and intermolecular C-H∙∙∙O/N/Se/Br/Cl) interactions and π-stacking interactions. The crystal structures of 2,4-diaryl-1,3-chalcogen azoles with both a pentafluorosulfuranyl (SF₅) group and a five-membered N-C-Se-C-C ring have been investigated in Chapter 5. A diverse picture of molecular configuration and intramolecular/intermolecular C-H∙∙∙N/Se/S and π-stacking interactions information are disclosed in selenamide, thiamides, 1,3-selenazoles and 1,3-thiazoles. Nine organo phosphorus-chalcogen macrocycles with nine- to fifteen-membered ring incorporating double OP(S)SC[sub]n or OP(Se)SeC[sub]n scaffolds have been discussed crystallographically in Chapter 6. The similar intramolecular and intermolecular C-H∙∙∙O, C-H∙∙∙S or C-H∙∙∙Se interactions are observed to lead to the similar packing networks.
Thesis, PhD Doctor of Philosophy
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