A dynamic look on molecular symmetry

Abstract

J.H. van’t Hoff’s seminal paper variously titled as either: Chemistry in Space, The Placement of Atoms in Space or other with similar wording, depending on the language it was published in, suggested that the structure of a molecule would be independent of its physical state: solid, liquid, vapor, gaseous, or in solution. However, this is definitely not true so much so that during the last decades many examples have accumulated showing that the structure of a molecule in a crystalline solid can differ substantially from its structure in solution. This would have important consequences not only on how molecules are structurally described and the way they react, but also that molecular symmetry may not be a static property and has to be considered from a dynamic point of view. To add additional evidence to this conception, we took advantage of a family of trans-1,4-di- and tetra-substituted cyclohexane derivatives that appear to have a centre of symmetry but show a substantial dipole moment in solution. In the present work, we used the trans-1,4-dicarboxymethylcyclohexane and its 1,4-dibrominated derivative and were able, through dipole moment determinations IR, Raman, NMR studies, and computational calculations with the SpinWorks, MOPAC, and MOLDEN programs, to confirm our assumption that the molecular symmetry and the molecular structure are dependent on the environment.