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Effect of the Metal on Disulfide/Thiolate Interconversion: Manganese versus Cobalt
Author(s) -
Gennari Marcello,
Brazzolotto Deborah,
Yu Shengying,
Pécaut Jacques,
Philouze Christian,
Rouzières Mathieu,
Clérac Rodolphe,
Orio Maylis,
Duboc Carole
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201502996
Subject(s) - chemistry , iodide , metal , cobalt , electrochemistry , disulfide bond , manganese , inorganic chemistry , context (archaeology) , transition metal , isostructural , metal ions in aqueous solution , crystallography , redox , crystal structure , catalysis , organic chemistry , electrode , paleontology , biochemistry , biology
It has recently been proposed that disulfide/thiolate interconversion supported by transition‐metal ions is involved in several relevant biological processes. In this context, the present contribution represents a unique investigation of the effect of the coordinated metal (M) on the M n + disulfide/M ( n +1)+ thiolate switch properties. Like its isostructural Co II ‐based parent compound, Co II 2 SS ( Angew. Chem. Int. Ed. 2014 , 53 , 5318), the new dinuclear disulfide‐bridged Mn II complex Mn II 2 SS can undergo an M II disulfide/M III thiolate interconversion, which leads to the first disulfide/thiolate switch based on Mn. The coordination of iodide to the metal ion stabilizes the oxidized form, as the disulfide is reduced to the thiolate. The reverse process, which involves the reduction of M III to M II with the concomitant oxidation of the thiolates, requires the release of iodide. The Mn II 2 SS complex slowly reacts with Bu 4 NI in CH 2 Cl 2 to afford the mononuclear Mn III thiolate complex Mn III I . The process is much slower (ca. 16 h) and much less efficient (ca. 30 % yield) with respect to the instantaneous and quantitative conversion of Co II 2 SS into Co III I under similar conditions. This distinctive behavior can be rationalized by considering the different electrochemical properties of the involved Co and Mn complexes and the DFT‐calculated driving force of the disulfide/thiolate conversion. For both Mn and Co systems, M II disulfide/M III thiolate interconversion is reversible. However, when the iodide is removed with Ag + , the M II 2 SS complexes are regenerated, albeit much slower for Mn than for Co systems.