Experimental and theoretical study of the HXeI⋯HCl and HXeI⋯HCCH complexes

The HXeI⋯HCl and HXeI⋯HCCH complexes are studied computationally and experimentally in a Xe matrix. In the experiments, three bands of the HXeI⋯HCl complex and one band of the HXeI⋯HCCH complex in the H-Xe stretching region are observed. The monomer-to-complex shifts are +94, +111, and +155 cm(-1) for the HXeI⋯HCl complex and +49 cm(-1) for the HXeI⋯HCCH complex. The bands of the complexed HCl molecules are also observed with large red shifts from the HCl monomer (-187, -252, and -337 cm(-1)). The ab initio calculations at the CCSD(T)/def2-TZVPPD level of theory predict two stable structures for the HXeI⋯HCl complex with interaction energies of -3.72 and -0.28 kcal mol(-1) and one structure for the HXeI⋯HCCH complex with an interaction energy of -2.67 kcal mol(-1) and the calculated monomer-to-complex shifts are in a good agreement with experiment (in the case of HXeI⋯HCl, for the stronger structure). The HXeI molecules are decomposed by broad-band infrared light; however, the decomposition is much more efficient for the HXeI monomer than for the complexes studied here as well as for the previously studied HXeI⋯HI and HXeI⋯HBr complexes. In fact, the decomposition efficiency decreases as the monomer-to-complex shift of the H-Xe stretching mode increases.