A monomeric manganese(II) catecholato complex: Synthesis, crystal structure, and reactivity toward molecular oxygen

[Display omitted] •A monomeric manganese(II) catecholato complex was synthesized and characterized.•The catecholato complex reacted with O2 to give a semiquinonato complex.•The manganese(II) semiquinonato complex was also structurally characterized. A monomeric manganese(II) catecholato complex with hydrotris(3-tert-butyl-5-isopropyl-1-pyrazolyl)borate (TptBu,iPr) was synthesized and characterized. X-ray analysis of the compound shows a tetrahedral manganese coordinated to one oxygen atom of the catecholato ligand and three nitrogen atoms of the TptBu,iPr ligand. The MnO distance (1.952(5) Å) is longer than the corresponding FeO distance (1.874(7) Å) in the analogous iron(II) TptBu,iPr complex due to the weaker Lewis acidity of manganese(II). Upon reacting of the manganese(II) complex with molecular oxygen, a manganese(II) semiquinonato complex was obtained, thus serving as an important model for catechol dioxygenase. This differs from the reaction of the iron(II) analog, which generates an iron(III) catecholato complex.