Flash-quench technique employed to study the one-electron reduction of triiodide in acetonitrile: evidence for a diiodide reaction product.
The one-electron reduction of triiodide (I(3)(-)) by a reduced ruthenium polypyridyl compound was studied in an acetonitrile solution with the flash-quench technique. Reductive quenching of the metal-to-ligand charge-transfer excited state of [Ru(II)(deeb)(3)](2+) by iodide generated the reduced ruthenium compound [Ru(II)(deeb(-))(deeb)(2)](+) and diiodide (I(2)(•-)). The subsequent reaction of [Ru(II)(deeb(-))(deeb)(2)](+) with I(3)(-) indicated that I(2)(•-) was a product that appeared with a second-order rate constant of (5.1 ± 0.2) × 10(9) M(-1) s(-1). After correction for diffusion and some assumptions, Marcus theory predicted a formal potential of -0.58 V (vs SCE) for the one-electron reduction of I(3)(-). The relevance of this reaction to solar energy conversion is discussed.
Farnum
Byron H
BH
Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
Gardner
James M
JM
Meyer
Gerald J
GJ