Strained π-systems as hydrogen bond acceptors: the case of benzyne

The behavior of strained π-systems with regard to their interaction with hydrogen bond (HB) donors was studied. The interaction of a model system, strained acetylene, and ortho-benzyne with hydrogen fluoride in their singlet and triplet electronic configuration was explored at the B3LYP/6-311++G∗∗ and MP2/6-311++G∗∗ levels. The energetic results indicate that there are two preferred approaches, the first with the hydrogen fluoride pointing towards one of the radical carbon atoms and the second that corresponds to the HB perpendicular to the π-bond. The atoms in molecules (AIM) analysis of the electron density shows a conflict catastrophic situation for several of the approaches.