EPR-ENDOR of the electronic structure from two nitrogenously ligated bis(.mu.-oxo)-manganese(III)-manganese(IV) model complexes spectroscopically relevant to the multi-manganese center of photosystem II

Synthesis, Structure, Electronic, Redox, and Magnetic Properties of a New Mixed-Valent Mn-Oxo Cluster: [Mn2III,IVO2(N,Nbispicen)2]3+ (N,Nbispicen =N,N-bis(2-pyridylmethyl)-1,2-diaminoethane)

“…Another example can be found in the published spectrum of [Mn 2 O 2 (TPA) 2 ] 3ϩ although this was not commented upon by the authors. [16] It should be noted that the topologies of both complexes are similar. A simulation (not shown) with an axial constraint was first achieved with the following parameters:…”

Ligation of D1-His332 and D1-Asp170 to the Manganese Cluster of Photosystem II from Synechocystis Assessed by Multifrequency Pulse EPR Spectroscopy

“…(78) ENDOR studies of such compounds have detected a 14 N HFI on the order of 9–13 MHz that is ascribed to such a coupling mode. (76,79) Also contributing to this large effective HFI is the projection factor of c = +2 for the coordinating Mn(III) ion in the dimer. (80) These projection factors are computed by determining the expectation value of the local electron spin projected onto the total electron spin of the molecule.…”

Two-dimensional 14N HYSCORE spectroscopy of the coordination geometry of ligands in dimanganese di-μ-oxo mimics of the oxygen evolving complex of photosystem II

“…15,[27][28][29][30][31] While masked by field inhomogeneity in the conventional field sweep EPR spectra, weak magnetic interactions with neighboring nuclei have been resolved and characterized by pulsed EPR spectroscopy. 30,[32][33][34][35] In particular, previous studies using ENDOR and ESEEM spectroscopy of mixed valence Mn(III)Mn(IV) di-m-oxo dimers have provided valuable information on nitrogen atoms that are axially coordinated at a Mn(III) ion. 33,[35][36][37][38][39] However, the magnetic parameters of nitrogen atoms coordinated at Mn(IV) ions and nitrogen atoms that are equatorially coordinated at Mn(III) ions remain scarce.…”

“…30,[32][33][34][35] In particular, previous studies using ENDOR and ESEEM spectroscopy of mixed valence Mn(III)Mn(IV) di-m-oxo dimers have provided valuable information on nitrogen atoms that are axially coordinated at a Mn(III) ion. 33,[35][36][37][38][39] However, the magnetic parameters of nitrogen atoms coordinated at Mn(IV) ions and nitrogen atoms that are equatorially coordinated at Mn(III) ions remain scarce.…”