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

Abstract

Utilizing a hexadentate ligand platform, a trinuclear manganese complex of the type ((H)L)Mn(3)(thf)(3) was synthesized and characterized ([(H)L](6-) = [MeC(CH(2)N(C(6)H(4)-o-NH))(3)](6-)). The pale-orange, formally divalent trimanganese complex rapidly reacts with O-atom transfer reagents to afford the μ(6)-oxo complex ((H)L)(2)Mn(6)(μ(6)-O)(NCMe)(4), where two trinuclear subunits bind the central O-atom and the ((H)L) ligands cooperatively bind both trinuclear subunits. The trimanganese complex ((H)L)Mn(3)(thf)(3) rapidly consumes inorganic azide ([N(3)]NBu(4)) to afford a dianionic hexanuclear nitride complex [((H)L)(2)Mn(6)(μ(6)-N)](NBu(4))(2), which subsequently can be oxidized with elemental iodine to ((H)L)(2)Mn(6)(μ(6)-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.