Kinetics and Mechanism of the Reaction of Hydrogen Sulfide with Diaquacobinamide in Aqueous Solution. Issue 25 (21st July 2014)

• Record Type: Journal Article
• Authors: Salnikov, Denis S.; Makarov, Sergei V.; van Eldik, Rudi; Kucherenko, Polina N.; Boss, Gerry R.
• Is Part Of: European journal of inorganic chemistry. Issue 25(2014)
• Page Start: 4123
• Page End: 4133
• Publication Date: 2014-07-21
• Subjects: Kinetics -- Reaction mechanisms -- Redox chemistry -- Hydrogen sulfide -- Cobinamide; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201402082
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract: We conducted a detailed kinetic study of the reaction of the vitamin B12 analog diaquacobinamide [(H2 O)2 Cbi(III)] with hydrogen sulfide in water from pH 3 to 11. The reaction proceeds in three steps: (1) the formation of three different complexes between cobinamide and hydrogen sulfide, viz., (HO – )(HS – )Cbi(III), (H2 O)(HS – )Cbi(III), and (HS – )2 Cbi(III); (2) inner‐sphere electron transfer (ISET) in the two complexes with one coordinated HS – ligand to form the reduced cobinamide complex [(H)S]Cbi(II); and (3) the addition of a second molecule of hydrogen sulfide to the reduced cobinamide. ISET does not proceed in the (HS – )2 Cbi(III) complex. The final products of the reaction between cobinamide and hydrogen sulfide were found to be independent of pH, and the main product is a complex of cobinamide(II) with the anion radical SSH2 – . Abstract : The reduction of diaquacobinamide [(H2 O)2 Cbi(III)] by hydrogen sulfide proceeds through inner‐sphere electron transfer (ISET) in the two complexes with one coordinated HS – ligand, viz., (HO – )(HS – )Cbi(III) and (H2 O)(HS – )Cbi(III), to form the reduced cobinamide complex [(H)S]Cbi(II). ISET does not proceed in the (HS – )2 Cbi(III) complex.