Prediction and characterization of HCCH···AuX (X = OH, F, Cl, Br, CH3, CCH, CN, and NC) complexes: a π Au-bond.

In this article, we performed quantum chemical calculations to study the π Au-bond in the HCCH···AuX (X = OH, F, Cl, Br, CH(3), CCH, CN, and NC) system. For comparison, we also investigated the HCCH···Au(+) and H(2)CCH(2)···AuF complexes. The equilibrium geometries and infrared spectra at the MP2 level were reported. The interaction energies were calculated at the MP2 and coupled-cluster single double triple levels. The natural bond orbital results support the Dewar-Chatt-Duncanson model. Moreover, we focused on the influence of X atom on the geometries, interaction energies, and orbital interactions as well as the comparison between HCCH···AuF and H(2)CCH(2)···AuF complexes. Although the π Au-bond in these complexes is electrostatic in nature, the weight of covalent nature is also important.