Relative influence of noncovalent interactions on the melting points of a homologous series of 1,2-dibromo- 4,5-dialkoxybenzenes

• Autores: Fonrouge, A.; Cecchi, F.; Alborés, P.; Baggio, R.; Cukiernik, F.D.
• Año de publicación: 2013
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: Acta Crystallogr Sect C Cryst Struct Commun 2013;69(2):204-208
• Materia: Aliphatic chains; Crystal stability; Dimethoxybenzene; Halogen bonding; Homologous series; Non-covalent interaction; Van der Waals contacts; Van Der Waals interactions; Benzene; Iodine; Ions; Melting point; Van der Waals forces; Bromine
• Institución: Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales

Crystal structures are presented for two members of the homologous series of 1,2-dibromo-4,5-dialkoxybenzenes, viz. those with decyloxy and hexadecyloxy substituents, namely 1,2-dibromo-4,5-bis(decyloxy)benzene, C26H44Br2O2, (II), and 1,2-dibromo-4,5-bis(hexadecyloxy)benzene, C38H68Br2O2, (III). The relative influences which halogen bonding, π- π stacking and van der Waals interactions have on these structures are analysed and the results compared with those already found for the lightest homologue, 1,2-dibromo-4,5- dimethoxybenzene, (I) [Cukiernik, Zelcer, Garland & Baggio (2008). Acta Cryst. C64, o604-o608]. The results confirm that the prevalent interactions stabilizing the structures of (II) and (III) are van der Waals contacts between the aliphatic chains. In the case of (II), weak halogen C - Br ⋯(Br - C) ′ interactions are also present and contribute to the stability of the structure. In the case of (III), van der Waals interactions between the aliphatic chains are almost exclusive, weaker C - Br ⋯ π interactions being the only additional interactions detected. The results are in line with commonly accepted models concerning trends in crystal stability along a homologous series (as measured by their melting points), but the earlier report for n = 1, and the present report for n = 10 and 16, are among the few providing single-crystal information validating the hypothesis.
Fil:Cecchi, F. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.
Fil:Alborés, P. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.
Fil:Cukiernik, F.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.