title: Experimental and theoretical investigation of NMR 2JHH coupling constant on six-membered ring systems containing oxygen or sulfur atoms.
abstract: Theoretical and experimental 2JHH coupling constants for six-membered rings containing oxygen or sulfur atoms were studied to investigate whether the 2JHH coupling constant can be used for stereoelectronic studies in heterocyclohexanes, instead of 1JCH, because it is well known that experimental measurements of 2JHH coupling constants at low temperature are much easier to determine than the corresponding 1JCH couplings. For all compounds studied here, the 2JHH coupling constants are affected by sigma*C-H antibonding occupancy together with bond angle effects. For cyclohexane and oxygen-containing compounds, the influence on the geminal coupling for Hax-C2-Heq and for X1-C2-X3 (X=O and C), bond angles are more pronounced than for the sulfur derivatives.
authors.affiliation: Chemistry Institute, State University of Campinas, Caixa Postal 6154 CEP:13084-971, Campinas, São Paulo, Brazil. tormena@iqm.unicamp.br
authors.forename: Cláudio F
authors.initials: CF
authors.lastname: Tormena
authors.forename: Janaína D
authors.initials: JD
authors.lastname: Vilcachagua
authors.forename: Viviane
authors.initials: V
authors.lastname: Karcher
authors.forename: Roberto
authors.initials: R
authors.lastname: Rittner
authors.forename: Rubén H
authors.initials: RH
authors.lastname: Contreras