Understanding the conformational changes and molecular structure of furoyl thioureas upon substitution.

• Autor(a) principal: Cairo, Raúl Ramos
• Data de Publicação: 2017
• Outros Autores: Stevens, Ana María Plutín, Oliveira, Tamires Donizeth de, Batista, Alzir Azevedo, Castellano, Eduardo Ernesto, Duque, Julio, Soria, Delia B., Fantoni, Adolfo C., Correa, Rodrigo de Souza, Erbene, Mauricio F.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFOP
• Texto Completo: http://www.repositorio.ufop.br/handle/123456789/9637; https://doi.org/10.1016/j.saa.2016.12.038
• topic: Thiourea derivatives; Vibrational spectroscopy; Single crystal structure determination; Molecular conformation

1-Acyl thioureas [R1C(O)NHC(S)NR2R3] are shown to display conformational flexibility depending on the degree of substitution at the nitrogen atom. The conformational landscape and structural features for two closely related thioureas having R1=2-furoyl have been studied. The un-substituted 2-furoyl thiourea (I) and its dimethyl analogue, i.e. 1-(2-furoyl)-3,3-dimethyl thiourea (II), have been synthesized and fully characterized by spectroscopic (FT-IR, 1H and 13C NMR) and elemental analysis. According to single crystal X-ray diffraction analysis, compounds I and II crystallize in the monoclinic space group P21/c. In the compound I, the trans–cis geometry of the almost planar thiourea unit is stabilized by intramolecular N\\H⋯O_C hydrogen bond between the H atom of the cis thioamide and the carbonyl O atom. In compound II, however, the acyl thiourea group is non-planar, in good agreement with the potential energy curve computed at the B3LYP/6-31+G(d,p) level of approximation. Centrosymmetric dimers generated by intermolecular N\\H⋯S_C hydrogen bond forming R2 2 (8) motif are present in the crystals. Intermolecular interactions have been rationalized in terms of topological partitions of the electron distributions and Hirshfeld surface analysis, which showed the occurrence of S⋯H, O⋯H and H⋯H contacts that display an important role to crystal packing stabilization of both thiourea derivatives.