PHOTOREDOX REACTIONS OF LEAD(IV) AND LEAD(II) HYDROXO COMPLEXES

Ligand-to-metal charge-transfer excitation of Pb(OH)62- in 0.1 M NaOH leads to the formation of Pb(OH)3- with phi = 0.07 at lambda(irr) = 254 nm. Hydrogen peroxide was detected as an oxidation product. Upon sp excitation, Pb(OH)3- in 0.1 M NaOH shows a yellow emission at lambda(max) = 570 nm with phi = 1.5 X 10(-3) at lambda(irr) = 254 nm. In the presence of oxygen, this emission is partially quenched (phi = 1.2 X 10(-3)) and Pb(OH)3- is photooxidized to Pb(OH)62- with phi = 0.02. A pseudo-photostationary state with 80% Pb(OH)62- is established. In the absence of oxygen, Pb(OH)3- undergoes a photoreduction with the deposition of elemental lead.