Helicity inversion and redox chemistry of chiral manganese(ii) cubanesElectronic supplementary information (ESI) available: UV-visible spectra of compounds 4 and 6, CD spectra of compounds 4 and 6, IR-spectra for Mn4(S-2-H)4 cubanes with various capping ligands, comparison of [Mn4(S-3-H)4]4+ cores in 8 and 9. Bond distances in [Mn4(1-H)4(OH)2(MeCN)2](ClO4)4MeCN(EtOH)2, 4, hydrogen bonds. CCDC 1003579-1003583. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4

The chiral ligand S -1,2-bis(1 H -benzimidazol-2-yl)ethanol, 1 , reacts with manganese( ii ) salts to form cubanes which readily undergo oxidation reactions leading either to a tetranuclear manganese( ii , iii ) mixed valence complex 4 or to a tetranuclear complex of ligand 5 where the secondary alcohol has been oxidised to an enolate. N-methylation of ligand 1 slows the oxidation reaction and stable manganese( ii ) cubanes may be isolated. The fully methylated ligand 2 gives a cubane of opposite helicity to that found previously for 1 with cobalt. The inversion may be explained by conformational analysis. Cyclic voltammetry suggests that the manganese cubanes reported here are insufficiently robust to store oxidising equivalents as in the oxygen evolving system of photosystem II. N-methylation of a benzimidazole ligand switches the helicity of a tetranuclear manganese complex and changes the redox behavior.