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Aromatic propellenes, part. 8 : semiempirical calculations and DNMR studies of hexakis (pyrazol-1-yl) benzenes

Título : Aromatic propellenes, part. 8 : semiempirical calculations and DNMR studies of hexakis (pyrazol-1-yl) benzenes
Autor : Foces Foces, Concepción
Llamas Saiz, Antonio L.
Fernández Castaño, Cristina
Claramunt, Rosa María
Escolástico, Consuelo
Lavandera Díaz, José Luis
Santa María, María Dolores
Jimeno, María Luisa
Elguero, José
Materias: Compuestos heterocíclicos.
Resumen : The stability of all possible conformers of hexa(pyrazol-1-yl)benzene [(pz)6bz], hexakis(3,5-dimethylpyrazol-1-yl)benzene [(dmpz)6bz], 1,2,4,5-tetra(pyrazol-1-yl)-3,6-bis(3,5-dimethylpyrazol-1-yl)benzene [(pz)4(dmpz)2bz] and 1,4-di(pyrazol-1-yl)-2,3,5,6-tetrakis(3,5-dimethylpyrazol-1-yl)benzene [(pz)2- (dmpz)4bz] has been determined by semiempirical AM1 calculations. In all series the absolute minimum corresponds to the conformation where the nitrogen lone pair of consecutive pyrazole rings is alternatively oriented to opposite sides of the benzene plane. The case of (pz)2(dmpz)4bz has been studied by 1 H NMR studies in solution. Three isomers have been identified and all the signals assigned. The slow evolution to other isomers from those found in the solid state has been followed by 1 H NMR spectroscopy thus allowing determination of the barrier to rotation of a (dmpz) substituent (ÄG‡ = 21–22 kcal mol21 ).
Descripción : En: Journal of the Chemical Society, Perkin Transactions, 2. ISSN 1472-7781. 1997, págs 2173-2177
URI : http://hdl.handle.net/10637/5521
Derechos: http://creativecommons.org/licenses/by-nc-nd/4.0/deed.es
Fecha de publicación : 29-oct-1997
Centro : Universidad San Pablo-CEU
Aparece en las colecciones: Medicina





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