Dihydrogen
Trioxide (HOOOH) Photoelimination from
a Platinum(IV) Hydroperoxo-Hydroxo Complex
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Abstract
Photolysis (380 nm) of <i>trans-</i>Pt(PEt<sub>3</sub>)<sub>2</sub>(Cl)(OH)(OOH)(4-trifluoromethylphenyl)
(<b>1</b>) at −78 °C in acetone-<i>d</i><sub>6</sub> or toluene-<i>d</i><sub>8</sub> yields HOOOH
(16–20%)
and <i>trans-</i>Pt(PEt<sub>3</sub>)<sub>2</sub>(Cl)(4-trifluoromethylphenyl)
(<b>2</b>). Also observed in acetone-<i>d</i><sub>6</sub> are H<sub>2</sub>O<sub>2</sub>, (CD<sub>3</sub>)<sub>2</sub>C(OH)(OOH), and (CD<sub>3</sub>)<sub>2</sub>C(OOH)<sub>2</sub>. Thermal
decomposition or room-temperature photolysis of <b>1</b> gives
O<sub>2</sub>, water, and <b>2</b>. Computational modeling (DFT)
suggests two intramolecular hydrogen-bonding-dependent triplet pathways
for the photolysis and two possible pathways for the thermolysis,
one involving proton transfer from the OOH to the OH ligand and the
other homolysis of the Pt–OOH bond, abstraction of the OH ligand,
and decomposition of the resulting H<sub>2</sub>O<sub>3</sub>. Trapping
studies suggest the latter pathway
