Br...Br and van der Waals interactions along a homologous series: crystal packing of 1,2-dibromo-4,5-dialkoxybenzenes

GUTIERREZ SUBURU, MATIAS E.; CUKIERNIK, FABIO D.; SEBASTIAN SUAREZ; FONROUGE, ANA; MULLER, FEDERICO; BAGGIO, RICARDO F.

ACTA CRYSTALLOGRAPHICA SECTION B-STRUCTURAL SCIENCE

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016 vol. 72 p. 693 - 701

0108-7681

The crystalline structures of four homologues of the1,2-dibromo-4,5-di(alkoxy)benzene series (Br2C6H2(OCnH2n+1)2 for n = 2, 12, 14 and18) have been solved by means of single-crystal crystallography. Comparisonalong the series, including the previously reported n =10 and n = 16 derivatives, shows a clear metric trend (b and c essentiallyfixed along the series and a growinglinearly with n), in spite ofsome subtle differences in space groups and/or packing modes. A uniform packingpattern for the aliphatic chains has been found for the n = 12 to 18homologues, which slightly differs from that of the n =10 derivative. The crystalline structures of all the higher homologues (n = 10 to 18) seem to arise from van derWaals interchain interactions and, to a lesser extent, type II Br...Brinteractions. The dominant role of interchain interactions provides directstructural support for the usual interpretation of melting point trends likethe one found along this series. Atoms-in -molecules (AIM; Bader, 1990, 1991) analysis allows a comparison ofthe relative magnitude of the interchain and Br...Brinteractions, an analysis validated by the measured melting enthalpies.