The photochemistry of the rhodizonate dianion at 483 nm has been studied in aqueous solution at pH 8.3. In the absence of oxygen no reaction was observed. In the presence of oxygen, 6.2× 10-5 M, the dianion was consumed with a quantum yield of 0.044. The oxidation apparently did not involve the formation of O2 (1Δg). Electron transfer from the excited dianion was observed with methyl viologen.
