INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
Supramolecular Architectures in o-Carboranyl Alcohols Bearing N-Aromatic Rings: Syntheses, Crystal Structures and Melting Points Correlation
FLORENCIA DI SALVO; BEATRIZ CAMARGO; YOLANDA GARCÍA; FRANCESC TEIXIDOR; CLARA VIÑAS; JOSÉ GINER PLANAS; MARK E. LIGHT; MICHAEL B. HURSTHOUSE
ROYAL SOC CHEMISTRY
Año: 2011 vol. 13 p. 5788 - 5788
The syntheses of new o-carboranyl alcohols bearing N-Aromatic rings 1-[R(hydroxy)methyl]-2-methyl-1,2-dicarba-closo-dodecaborane (R = 6-methyl-2-pyridyl 1b, 3-pyridyl 1c, 2-quinolyl 1e, 4-quinolyl 1f), 1-[R(hydroxy)methyl]-1,2-dicarba-closo-dodecaborane (R = 2-pyridyl 2a, 6-methyl-2-pyridyl 2b, 3-pyridyl 2c, 4-pyridyl 2d, 2-quinolyl 2e, 4-quinolyl 2f)) are reported. The crystal structures of all compounds, except that for 1b, are reported and compared with those related compounds previously synthesized by us (1-[R(hydroxy)methyl]-2-methyl-1,2-dicarba-closo-dodecaborane (R = 2-pyridyl 1a, 4-pyridyl 1d)). We provide an analysis of these compounds by means of X-ray crystallography, NMR/IR spectroscopies, thermal analyses and gas phase calculations in the context of crystal engineering. The results show that the crystal packings for these alcohols are dominated by the supramolecular OH∙∙∙N heterosynthon, but also include other weaker interactions such as CH∙∙∙O hydrogen bonds, H∙∙∙H contacts and some degree of (C/B)H∙∙∙p interactions. There are four types of OH∙∙∙N hydrogen bonded chains, two giving rise to high melting compounds (1c, 1d, 1f, 2c, 2d, and 2f) and other two affording lower melting point compounds (1a, 2a and 2b). The lowest melting compounds (1e and 2e) show no such infinite OH∙∙∙N hydrogen bonding networks and only intramolecular OH∙∙∙N hydrogen bonds. We correlate the presence of the infinite OH∙∙∙N hydrogen bonding network in the crystal structure for the pyridine derivatives with their melting points. Gas phase calculations shows that the energy for the OH∙∙∙N interactions in hydrogen bonded dimers are in the range 48 Kcal/mol.