The halogenoxygen interaction in 3-halogenopropenal revisited – The dimer model vs. QTAIM indications

Abstract: Even though a bond path and the corresponding bond critical point were found for the intramolecular XO (X=Cl,Br) interaction in 3-halogenopropenal, thus according to QTAIM suggesting the stabilizing nature of this interaction, it was shown that this contact is repulsive. In order to utilize the well-defined energy of the intermolecular interaction, a dimer model was used. The C–XOt from the ZZ conformer of 3-halogenopropenal was preserved with its original geometrical arrangement. Such approach leads to the conclusion according to which the presence of a bond path and the corresponding bond critical point do not necessarily indicate a stabilizing interaction between a pair of atoms, but rather is a direct consequence of a large accumulation of the electron density between atoms. Values of QTAIM parameters characterizing both BCP of XO and RCP remain rather unchanged if the C–XOt with its preserved geometry is embedded in a dimer. It was also shown that atoms X and O are interacting by negative surfaces of the molecular electrostatic potential. Also the charge transfer between interacting fragments is opposite to expected. [Copyright &y& Elsevier]