Evaluation of Manganese Cubanoid Clusters for Water Oxidation Catalysis: From Well‐Defined Molecular Coordination Complexes to Catalytically Active Amorphous Films. Issue 21 (28th September 2021)

• Record Type: Journal Article
• Authors: Hosseinmardi, Soosan; Scheurer, Andreas; Heinemann, Frank W.; Kuepper, Karsten; Senft, Laura; Waldschmidt, Pablo; Ivanović‐Burmazović, Ivana; Meyer, Karsten
• Is Part Of: ChemSusChem. Volume 14:Issue 21(2021)
• Page Start: 4741
• Page End: 4751
• Publication Date: 2021-09-28
• Subjects: cubanes -- electrocatalysis -- electrodeposition -- manganese -- water splitting; Green chemistry -- Periodicals; Sustainable engineering -- Periodicals; Chemistry -- Periodicals; Chemical engineering -- Periodicals; 660
• DOI: 10.1002/cssc.202101451
• Languages: English
• ISSNs: 1864-5631

Abstract

Abstract: With a view to developing multimetallic molecular catalysts that mimic the oxygen‐evolving catalyst (OEC) in Nature's photosystem II, the synthesis of various dicubanoid manganese clusters is described and their catalytic activity investigated for water oxidation in basic, aqueous solution. Pyridinemethanol‐based ligands are known to support polynuclear and cubanoid structures in manganese coordination chemistry. The chelators 2, 6‐pyridinedimethanol (H2 L 1 ) and 6‐methyl‐2‐pyridinemethanol (HL 2 ) were chosen to yield polynuclear manganese complexes; namely, the tetranuclear defective dicubanes [Mn II 2 Mn III 2 (HL 1 )4 (OAc)4 (OMe)2 ] and [Mn II 2 Mn III 2 (HL 1 )6 (OAc)2 ] (OAc)2 ⋅2 H2 O, as well as the octanuclear‐dicubanoid [Mn II 6 Mn III 2 (L 2 )4 (O)2 (OAc)10 (HOMe/OH2 )2 ]⋅3MeOH⋅MeCN. In freshly prepared solutions, polynuclear species were detected by electrospray ionization mass spectrometry, whereas X‐band electron paramagnetic resonance studies in dilute, liquid solution suggested the presence of divalent mononuclear Mn species with g values of 2. However, the magnetochemical investigation of the complexes' solutions by the Evans technique confirmed a haphazard combination of manganese coordination complexes, from mononuclear to polynuclear species. Subsequently, the newly synthesized and characterized manganese molecular complexes were employed as precursors to prepare electrode‐deposited films in a buffer‐free solution to evaluate and compare their stability and catalytic activity for water oxidation electrocatalysis. Abstract : Film star : Cubanoid tetranuclear and octanuclear manganese complexes are synthesized and electrodeposited on an active surface to compare their electrocatalytic activity for the water oxidation reaction. A simple, direct relationship is derived between the manganese content in the precursor and the oxygen evolution activity of the deposited films.