title: Does a stabilising interaction favouring the Z,Z configuration of -S-N=S=N-S- systems exist?
abstract: The existence of the orbital interaction presented in the literature as being the cause for the stabilisation of the Z,Z configuration of Ph-S-N=S=N-S-Ph (1) and its derivatives in the crystal phase, has been investigated. The results of theoretical calculations at the DFT/B3LYP/6-311+G* level of theory suggest that such a stabilising interaction might not exist or be extremely weak and that packing forces must be the main cause of the observed Z,Z configuration in the solid. To reach this conclusion structural and energetic parameters were combined to study the bonding in these -S-N=S=N-S- systems. For the analogous Ph-Se-N=S=N-Se-Ph (2) in particular the isomeric equilibrium in solution found in the variable-temperature 77Se NMR spectrum indicates that, in the gas phase or in solution, the observed Z,Z configuration is not stabilised to a greater extent than the Z,E configuration.
authors.affiliation: Department of Chemistry, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium.
authors.forename: Karla
authors.initials: K
authors.lastname: Tersago
authors.forename: Marcos
authors.initials: M
authors.lastname: Mandado
authors.forename: Christian
authors.initials: C
authors.lastname: Van Alsenoy
authors.forename: Irina Yu
authors.initials: IY
authors.lastname: Bagryanskaya
authors.forename: Mikhail K
authors.initials: MK
authors.lastname: Kovalev
authors.forename: Alexander Yu
authors.initials: AY
authors.lastname: Makarov
authors.forename: Yuri V
authors.initials: YV
authors.lastname: Gatilov
authors.forename: Makhmut M
authors.initials: MM
authors.lastname: Shakirov
authors.forename: Andrey V
authors.initials: AV
authors.lastname: Zibarev
authors.forename: Frank
authors.initials: F
authors.lastname: Blockhuys