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Br…Br and van der Waals interactions along a homologous series: crystal packing of 1,2‐dibromo‐4,5‐dialkoxybenzenes
Author(s) -
Suarez Sebastián A.,
Muller Federico,
Gutiérrez Suburu Matías E.,
Fonrouge Ana,
Baggio Ricardo F.,
Cukiernik Fabio D.
Publication year - 2016
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520616009835
Subject(s) - homologous series , van der waals force , crystal (programming language) , series (stratigraphy) , van der waals strain , chemistry , crystallography , van der waals surface , van der waals radius , computational chemistry , molecule , organic chemistry , computer science , geology , paleontology , programming language
The crystalline structures of four homologues of the 1,2‐dibromo‐4,5‐dialkoxybenzene series [Br 2 C 6 H 2 (OC n H 2 n + 1 ) 2 for n = 2, 12, 14 and 18] have been solved by means of single‐crystal crystallography. Comparison along the series, including the previously reported n = 10 and n = 16 derivatives, shows a clear metric trend ( b and c essentially fixed along the series and a growing linearly with n ), in spite of some subtle differences in space groups and/or packing modes. A uniform packing pattern for the aliphatic chains has been found for the n = 12 to 18 homologues, which slightly differs from that of the n = 10 derivative. The crystalline structures of all the higher homologues ( n = 10–18) seem to arise from van der Waals interchain interactions and, to a lesser extent, type II Br…Br interactions. The dominant role of interchain interactions provides direct structural support for the usual interpretation of melting point trends like that found along this series. Atoms in Molecules (AIM) analysis allows a comparison of the relative magnitude of the interchain and Br…Br interactions, an analysis validated by the measured melting enthalpies.