Noble Gas–Tungsten Peroxide Complexes in Noble Gas Matrixes: Infrared Spectroscopy and Density Functional Theoretical Study

The matrix isolation infrared spectroscopic and quantum chemical calculation results indicate that tungsten oxo and mono-superoxide, WO₃ and (η²-O₂)­WO₂, coordinate noble gas atoms in forming noble gas–tungsten oxide complexes. The results showed that both WO₃ and (η²-O₂)­WO₂ oxides can coordinate one Ar or Xe atom in solid noble gas matrixes; otherwise, tungsten mono- and dioxides cannot. Hence, the WO₃ and (η²-O₂)­WO₂ molecules trapped previously in solid argon noble gas matrixes should be regarded as the WO₃(Ar) oxide and (η²-O₂)­WO₂(Ar) peroxide complexes. When annealing, the lighter Ar atom can be replaced by a heavier xenon atom to form WO₃(Xe) and (η²-O₂)­WO₂(Xe) complexes. What’s more, upon UV photolysis, both Ar and Xe atoms can be replaced by oxygen to form a tungsten disuperoxide (η²-O₂)₂WO₂ complex. The binding energies were predicted to be 25.7, 16.6, 9.4, 14.7, and 8.1 kcal/mol for the (η²-O₂)₂WO₂, WO₃(Xe), WO₃(Ar), (η²-O₂)­WO₂(Xe), and (η²-O₂)­WO₂(Ar) complexes at the CCSD­(T)//M06-2X-D3//def2-TZVP/DGDZVP/SDD level. The substitution law, O₂ > Xe > Ar, can be interpreted according to the chemical reaction energies calculated to be −6.6 and +11.0 kcal/mol, respectively, for the equation formulas Xe + (η²-O₂)­WO₂(Ar) = (η²-O₂)­WO₂(Xe) + Ar and O₂ + (η²-O₂)­WO₂(Xe) = (η²-O₂)₂WO₂ + Xe at the same level.