Gas-Phase Room-Temperature Detection of the tert-Butyl Hydroperoxide Dimer

Wehave detected the tert-butyl hydroperoxidedimer, (t-BuOOH)(2), in the gas phase atroom temperature using conventional FTIR techniques. The dimer isidentified by an asymmetric absorbance band assigned to the fundamentalhydrogen-bound OHb-stretch. The weighted band maximum ofthe dimer OHb-stretch is located at & SIM;3452 cm(-1), red-shifted by & SIM;145 cm(-1) from the monomer OH-stretching band. The gas-phase dimer assignmentis supported by Ar matrix isolation FTIR experiments at 12 K and experimentswith a partially deuterated sample. Computationally, we find the lowestenergy structure of (t-BuOOH)(2) to be adoubly hydrogen bound six-membered ring with non-optimal hydrogenbond angles. We estimate the gas-phase constant of dimer formation, K, to be 0.4 (standard pressure of 1 bar) using the experimentalintegrated absorbance and a theoretically determined oscillator strengthof the OHb-stretching band.