Effect of the Metal on Disulfide/Thiolate Interconversion: Manganese versus Cobalt. Issue 51 (9th November 2015)

• Record Type: Journal Article
• Authors: Gennari, Marcello; Brazzolotto, Deborah; Yu, Shengying; Pécaut, Jacques; Philouze, Christian; Rouzières, Mathieu; Clérac, Rodolphe; Orio, Maylis; Duboc, Carole
• Is Part Of: Chemistry. Volume 21:Issue 51(2015)
• Page Start: 18770
• Page End: 18778
• Publication Date: 2015-11-09
• Subjects: cyclic voltammetry -- manganese -- molecular devices -- redox chemistry -- UV/Vis spectroscopy; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201502996
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: 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 complexMn 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. TheMn II 2 SS complex slowly reacts with Bu4 NI in CH2 Cl2 to afford the mononuclear Mn III thiolate complexMn 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 ofCo II 2 SS intoCo 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 +, theM II 2 SS complexes are regenerated, albeit much slower for Mn than for Co systems. Abstract : Molecular ON/OFF switch : The first disulfide (see scheme, left)/thiolate (see scheme, right) molecular switch based on manganese is reported and compared to the parent cobalt‐based system. Coordination of iodide to the metal ions stabilizes the oxidized form, as the disulfide is reduced to the thiolate, whereas the reverse process requires the release of iodide.