Characterisation of weak intramolecular interactions in the topology of the experimental charge density of 2,2′-ethynylenedibenzoic acid

A multipole model of the charge density distribution in the di-substituted alkyne title compound containing weak intramolecular interactions as defined by the topology of the charge density, has been obtained from high-resolution single crystal diffraction data. Bond paths are located between formally non-bonded C and O atom pairs and also between a pair of O atoms. This observation of weak intramolecular interactions in an experimentally derived charge density proves that the multipole modeling formalism is sufficiently sensitive to detect such features which are small on an absolute scale. Evidence is presented which suggests that the cis conformation of the molecule in this particular crystalline state is due to strong intermolecular hydrogen bonding.