The (Tetraazaannulene)copper-Catalyzed Reduction of Sulfur(IV) Species. A Pulse-Radiolysis and Theoretical Study of the Associated Reaction Mechanism
✍ Scribed by Guillermo Ferraudi; Guillermina Estiu; A. Graham Lappin; Manuel Villagran; Juan P. Muena; Juan Costamagna; Jose Zagal
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- German
- Weight
- 426 KB
- Volume
- 92
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
Abstract
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The monomeric species, [Cu^II^{H~x~(tmdnTAA)}]^x+^ (x=0, 1, and 2, and (tmdnTAA)^2−^=[5,7,12,14]tetramethyldinaphtho[b,i][1,4,8,11]tetraaza[14]annulenato(2−)=7,9,18,20‐tetramethyldinaphtho[2,3‐b : 2′,3′‐i] [1,4,8,11]tetraazacyclotetradecinato(2−)) catalyze the electrochemical reduction of SO~2~(aq) in homogeneous solution. A pulse‐radiolytic study of the reaction of the [Cu^I^(tetraazaannulene)] complexes with S^IV^ species revealed the formation of Cu^I^SO~2~ adducts. The formation of Cu^I^SO~2~ adducts prevents the disproportionation of the Cu^I^ complexes and precedes the reduction of the S^IV^ species to S~2~O$\rm{ _4^{2 - } }$. DFT Calculations were carried out to establish the structure and stability of the Cu^I^SO~2~ adducts. A good agreement between the calculated and recorded electronic spectrum of the Cu^I^SO~2~ adducts corroborated the formation of species with SO~2~ coordinated to Cu^I^ through the O‐atom.