Selective Photoproduction of O2 from the Mn4O4 Cubane Core: A Structural and Functional Model for the Photosynthetic Water-Oxidizing Complex

Cores for thought! A new [Mn4O4]6+ “cubane” core complex (L6Mn4O4) with six facially bridging phosphinate chelate ligands (L−=(MePh)2PO2−) was synthesized. Photo-excitation releases molecular O2 by intramolecular coupling of two core oxygen atoms and selective rearrangement to a [Mn4O2]6+ “butterfly” core ([L5Mn4O2]+; see scheme). Thus the Mn4O4 cubane core exhibits unique reactivity in O2 evolution which may account for its presence in the photosynthetic enzyme.