Matrix-isolation and theoretical study of the HXeCCXeH⋯HCCH and HXeCC⋯HCCH complexes
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⋯HCCH (about +17 cm−1) and HXeCC⋯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⋯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⋯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⋯HCCH and HXeCC⋯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.