Matrix-isolation and theoretical study of the HXeCCXeH⋯HCCH and HXeCC⋯HCCH complexes

Abstract

We report on the identification of the complexes of two noble-gas hydrides, HXeCCXeH and HXeCC, with acetylene. These complexes were prepared by photolysis (250 nm) and annealing (55-65 K) of HCCH/Xe matrices. The experimentally observed monomer-to-complex shifts of the H-Xe stretching modes of the HXeCCXeH center dot center dot center dot HCCH (about +17 cm(-1)) and HXeCC center dot center dot center dot HCCH complexes (from +20 to +46 cm(-1)) indicate the stabilization of the H-Xe bond relatively to the monomers. The CCSD/cc-pVTZ calculations predict two structures for each complex. The HXeCCXeH center dot center dot center dot HCCH complex has quasi T-shaped and linear structures, with the H-Xe stretching modes blue-shifted and red-shifted by about +27 and -9 cm(-1), respectively. The HXeCC center dot center dot center dot HCCH complex has bent and T-shaped structures, with the H-Xe stretching modes blue-shifted by about +46 and +42 cm(-1), respectively. Based on the calculations, the experimental bands of the HXeCCXeH center dot center dot center dot HCCH and HXeCC center dot center dot center dot HCCH complexes are assigned to the quasi T-shaped and bent structures, respectively. Complexes of an open-shell noble-gas hydride and of a molecule with two noble-gas atoms are reported for the first time.