摘要:
A non-aqueous electrochemical study of dithizone, H(2)Dz, 1, is compared with the chemical oxidation and reduction profile of this versatile ligand. Chemical oxidation of 1 by 12 initially leads to an isolatable disulfide-bridged species, (HDz)(2), 2(2), but ultimately monomeric dehydrodithizone. Dz, 3, is formed. Electrochemically, in CH2Cl2/0.1 mol dm(-3) [N(Bu-n)(4)][B(C6F5)(4)], two oxidation processes are observed for 1. Evidence of the electrochemical formation of the dimer 2(2) was found, but on a CV timescale the fully oxidized species, 2(2) (oxidized), did not convert to the chemically stable species 3. Regeneration of 1 during an irreversible electrochemical reduction of the electrochemically generated fully oxidized species, 2(2) (oxidized), was detected. Two further one-electron electrochemical irreversible reduction steps were also identified to ultimately generate H3Dz-, 8, one of the synthetic precursors to 1. In contrast, resolution and identification of the electron transfer steps of 1 in both dimethylsulfoxide, DMSO, or in CH2Cl2/0.1 mol dm(-3) [N('' Bu)(4)][PF6] were hampered by solvation and ion paring of [PF6](-) especially with the oxidized species of 1. A metathesis of water-soluble potassium dithizonate, KHDz, 4b, led to lipophilic [N(Bu-n)(4)][HDz], 4c. (C) 2010 Elsevier Ltd. All rights reserved.