Abstract
<jats:p>The trinuclear cluster of manganese(III) acetate (1) is widely employed in synthetic carbon functionalization reactions, yet its coordination chemistry and solution-state properties are not well studied. This is primarily due to the low solubility of 1, even when coordinated with pyridine and related neutral N-donor ligands. Herein, we overcome this challenge and report new coordination complexes derived from 1 or mononuclear Mn(III) halide precursors. A family of well-defined and soluble Mn(III) acetate complexes with neutral pnictogen-oxide ylide (PnO) donors (pyridine-N-oxide, triphenylphosphine oxide, and trimethylamine-N-oxide) was prepared. Their structures range from closely resembling the trinuclear motif of 1, linear chains, and higher nuclearity clusters. Critically, we unequivocally demonstrated that acid breaks up the trinuclear cluster into mononuclear MnIII species that can be trapped through coordination of PnO ligands. Substrate-bound intermediates were captured by inclusion of PnO ligands in cyclization reactions between α-methylstyrene with acetylacetone.</jats:p>