Oxygen‐Atom Transfer Chemistry and Thermolytic Properties of a Di‐tert‐Butylphosphate‐Ligated Mn₄O₄ Cubane

Abstract

[Mn4O4{O2P(OtBu)2}6] (1), an Mn4O4 cubane complex combining the structural inspiration of the photosystem II oxygen-evolving complex with thermolytic precursor ligands, was synthesized and fully characterized. Core oxygen atoms within complex 1 are transferred upon reaction with an oxygen-atom acceptor (PEt3), to give the butterfly complex [Mn4O2{O2P(OtBu)2}6(OPEt3)2]. The cubane structure is restored by reaction of the latter complex with the O-atom donor PhIO. Complex 1 was investigated as a precursor to inorganic Mn metaphosphate/pyrophosphate materials, which were studied by X-ray absorption spectroscopy to determine the fate of the Mn4O4 unit. Under the conditions employed, thermolyses of 1 result in reduction of the manganese to Mn(II) species. Finally, the related butterfly complex [Mn4O2{O2P(pin)}6(bpy)2] (pin = pinacolate) is described.

Jahn‐Teller Effects in a Vanadate‐Stabilized Manganese‐Oxo Cubane Water Oxidation Catalyst

“…[15,68] However, when changing to six bis(p-methoxyphenyl)phosphinate ligands, [7,68] the Mn3444 oxidation state showed one JT axis and the Mn3344 oxidation state showed two antiparallel JT axes (compare Figure 4). The same antiparallel JT arrangement for Mn3344 was reported for a complex with six di(t-butyl) phosphate ligands [69] and another complex with six dimethylarsinate ligands. [23] This might indicate that in homoleptic Mn 4 O 4 cubanes, antiparallel JT arrangements might be energetically favorable.…”

Stabilization of reactive Co 4 O 4 cubane oxygen-evolution catalysts within porous frameworks

“…Furthermore, the local environment and charge state of the cobalt for the [Co 4 O 4 ] building units are the same in all of the materials under study, as indicated by the X-ray absorption near edge structure (XANES). This technique has been used for the photosystem II active site (44)(45)(46)(47)(48), the cobalt oxide wateroxidation catalyst (49,50), and Mn-oxo cubanes (9,(51)(52)(53).…”

Structural models of the biological oxygen-evolving complex: achievements, insights, and challenges for biomimicry

“…), showed almost equivalent Mn-O bond lengths, which was attributed to valence delocalization at elevated temperature (298 K). Lowering the temperature to 150 K led to a small differentiation of Mn-O bonds 147 and the bond length inequivalence was also shown to depend on the ligand L. 148,149 The crystal structure of the singly oxidized product of the complex [Mn 4 O 4 ] 7+ demonstrates a trigonal distortion compared to the tetragonal symmetry of the parent complex, i.e. [Mn 4 O 4 ] 6+ .…”