Oxidative Atom-Transfer to a Trimanganese Complex To Form Mn6(μ6-E) (E = O, N) Clusters Featuring Interstitial Oxide and Nitride Functionalities

Utilizing a hexadentate ligand platform, a trinuclear manganese complex of the type (HL)Mn3(thf)3 was synthesized and characterized ([HL]6– = [MeC(CH2N(C6H4-o-NH))3]6–). The pale-orange, formally divalent trimanganese complex rapidly reacts with O-atom transfer reagents to afford the μ6-oxo complex (HL)2Mn6(μ6-O)(NCMe)4, where two trinuclear subunits bind the central O-atom and the (HL) ligands cooperatively bind both trinuclear subunits. The trimanganese complex (HL)Mn3(thf)3 rapidly consumes inorganic azide ([N3]NBu4) to afford a dianionic hexanuclear nitride complex [(HL)2Mn6(μ6-N)](NBu4)2, which subsequently can be oxidized with elemental iodine to (HL)2Mn6(μ6-N)(NCMe)4. EPR and alkylation of the interstitial light atom substituent were used to distinguish the nitride from the oxo complex. The oxo and oxidized nitride complexes give rise to well-defined Mn(II) and Mn(III) sites, determined by bond valence summation, while the dianionic nitride shows a more symmetric complex, giving rise to indistinguishable ion oxidation states based on crystal structure bond metrics.