Formation of a Cluster with the M4^IIM2^III Metal Core upon the Oxidation of Manganese(II) Cymantrenecarboxylate Adduct with Air Oxygen in Tetrahydrofuran

The reaction of manganese(II) acetate hydrate with cymantrenecarboxylic acid under inert atmosphere gave the complex [Mn(Thf)2(OH2)4][OOCC5H4Mn(CO)3]2 (I), which was highly unstable to air oxygen and temperature of the adduct, in which the anions occupy the outer-sphere positions. The oxidation of the mother liquor after isolation of the single crystals of I afforded the complex Mn6(µ4-O)2[µ,η2-OOCC5H4Mn(CO)3]2[µ-OOCC5H4Mn(CO)3]8(OH2)4·5C6H6·THF·3H2O (II). According to X-ray diffraction data, the metal core of II was a hexanuclear cluster $${\text{Mn}}_{4}^{{{\text{II}}}}{\text{Mn}}_{2}^{{{\text{III}}}}$$ containing mixed-valence metal atoms. Apart from X-ray diffraction, the obtained unstable complexes were characterized by elemental analysis and IR spectroscopy (powders).