title: Structural Conformers of (1,3-Dithiol-2-ylidene)ethanethioamides: The Balance between Thioamide Rotation and Preservation of Classical Sulfur-Sulfur Hypervalent Bonds.
abstract: The reaction of N-(2-phthalimidoethyl)-N-alkylisopropylamines and S2Cl2 gave 4-N-(2-phthalimidoethyl)-N-alkylamino-5-chloro-1,2-dithiol-3-thiones that quantitatively cycloadded to dimethyl or diethyl acetylenedicarboxylate to give stable thioacid chlorides, which in turn reacted with one equivalent of aniline or a thiole to give thioanilides or a dithioester. Several compounds of this series showed atropisomers that were studied by a combination of dynamic NMR, simulation of the signals, conformational analysis by DFT methods, and single crystal X-ray diffraction, showing a good correlation between the theoretical calculations, the experimental values of energies, and the preferred conformations in the solid state. The steric hindering of the crowded substitution at the central amine group was found to be the reason for the presence of permanent atropisomers in this series of compounds and the cause of a unique disposition of the thioxo group at close-to-right angles with respect to the plane defined by the 1,3-dithiole ring in the dithiafulvene derivatives, thus breaking the sulfur-sulfur hypervalent bond that is always found in this kind of compounds.
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Burgos, 09001 Burgos, Spain.
authors.forename: Pedro
authors.initials: P
authors.lastname: Fuertes
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Burgos, 09001 Burgos, Spain.
authors.forename: María
authors.initials: M
authors.lastname: García-Valverde
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Burgos, 09001 Burgos, Spain.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Pascual
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Burgos, 09001 Burgos, Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Rodríguez
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Burgos, 09001 Burgos, Spain.
authors.forename: Josefa
authors.initials: J
authors.lastname: Rojo
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Burgos, 09001 Burgos, Spain.
authors.forename: José
authors.initials: J
authors.lastname: García-Calvo
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Burgos, 09001 Burgos, Spain.
authors.forename: Patricia
authors.initials: P
authors.lastname: Calvo
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Burgos, 09001 Burgos, Spain.
authors.forename: José V
authors.initials: JV
authors.lastname: Cuevas
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Burgos, 09001 Burgos, Spain.
authors.forename: Gabriel
authors.initials: G
authors.lastname: García-Herbosa
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Burgos, 09001 Burgos, Spain.
authors.forename: Tomás
authors.initials: T
authors.lastname: Torroba
mesh_terms: D015394:Molecular Structure; D011789:Quantum Theory; D012399:Rotation; D013455:Sulfur / Q000737:chemistry*; D013854:Thioamides / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: C000599557:(1,3-dithiol-2-ylidene)ethanethioamide; D013854:Thioamides; D013455:Sulfur