Syntheses and properties of metal-centered mixed-valent [NEt4]{MnII ⊂[MnII3MnIII3Cl6(L)6]} manganese wheels

Upon reaction of N-substituted diethanolamines H2L2-4 (4,6, 7) with cesium carbonate and bis(tetraethylammonium) tetrachloromanganate(II) in acetonitrile in the presence of air, the metal-centered mixed-valent manganese wheels [NEt4]{Mn-II subset of[(Mn3Mn3Cl6)-Mn-II-Cl-III(L2-4)(6)]} (8-10) were generated. X-ray crystallographic structure analyses revealed, that 8-10 are principally isostructural and consist of an alternating ring of three Mn-II and three Mn-III ions, centered by an additional Mn-II ion. The cyclic voltammograms of 8 and 10 displayed three quasi-reversible oxidation processes, which are attributed to the subsequent one electron-oxidations of the three peripheral Mn-II ions to Mn-III. Oxidation of the central Mn-II ion is not observed within the applied potential. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).