A structural study of new tetrakis(1H-pyrazol-1-yl)methanes

• Autor(a) principal: Silva, Vera L.M.
• Data de Publicação: 2019
• Outros Autores: Silva, Artur M.S., Claramunt, Rosa M., López, Concepción, Sanz, Dionisia, Infantes, Lourdes, López, Ángela Martínez, Reviriego, Felipe, Alkorta, Ibon, Elguero, José
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/36703
• topic: Tetrakis(1H-pyrazol-1-yl)methanes; X-ray structures; NMR. SSNMR; DFT; GIAO

Tetrakis(1H-pyrazol-1-yl)methanes are very rare compounds of which only two are known: the unsubstituted 1 obtained classically by Hückel in 1937 from carbon tetrachloride and prepared again several times and the 3,5-dimethyl substituted 2 obtained serendipitously by Pombeiro in 2009. We have now extended this group to include four new derivatives 8, 9, 11 and 12 bearing methyl groups. The X-ray crystal structure of the four compounds has been determined. They have been studied by NMR both in solution (1H, 13C, 15N) and in the solid state (13C and 15N). DFT calculations of the six compounds (geometries, energies and absolute shieldings) have been used to discuss the experimental observations.