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|Type:||Artigo de periódico|
|Title:||Effect Of Sulfur Oxidation On The Transmission Mechanism Of4jhh Nmr Coupling Constants In 1,3-dithiane|
|Abstract:||Long-range 4JHH couplings in 1,3-dithiane derivatives are rationalized in terms of the effects of hyperconjugative interactions involving the S=0 group. Theoretical and experimental studies of 4JHH couplings were carried out in 1,3-dithiane-l-oxide (2), cw-l,3-dithiane-l,3-dioxide (3), l,3-dithiane-l,l,3-trioxide (4), and 1,3-dithiane-1,1,3,3-tetraoxide (5) compounds. Hyperconjugative interactions were studied with the natural bond orbital, NBO, method. Hyperconjugative interactions involving the LP O, oxygen lone pair and σ*C2-S1 and σ*S1-C6 antibonding orbitals yield an increase of 4JHeq-Heq couplings. Long-range 4JHax-Hax couplings were also observed between hydrogen atoms in axial orientation, which are rationalized as originating in hyperconjugative interactions involving the bonding σC6-h axand antibonding σ*S=O orbitals. The symmetry for orbital interactions is possible only when the S=0 group is in the axial orientation. © 2009 American Chemical Society.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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