Matrix-isolation and ab initio study of HXeCCH complexed with acetylene

The HXeCCH ⋯ H2C2 complex has been characterized by IR spectroscopy in a xenon matrix and ab initio calculations. This species exhibits a blue shift of the HXe stretching mode (19–28 cm−1) in comparison with the HXeCCH monomer, which indicates stabilization of the HXe bond upon complexation. The complex results from annealing-induced diffusion of acetylene molecules above 50 K to isolated HXeCCH formed at lower temperature. In addition, a weak absorption with a blue shift of +51 cm−1 was tentatively assigned to the HXeCCH complex with two acetylene molecules. These experimental observations are supported by ab initio calculations.