English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT

Released

Journal Article

Spin State as a Marker for the Structural Evolution of Nature’s Water-Splitting Catalyst

MPS-Authors
/persons/resource/persons237626

Krewald,  Vera
Research Department Neese, Max Planck Institute for Chemical Energy Conversion, Max Planck Society;

/persons/resource/persons237685

Retegan,  Marius
Research Department Neese, Max Planck Institute for Chemical Energy Conversion, Max Planck Society;

/persons/resource/persons216825

Neese,  Frank
Research Department Neese, Max Planck Institute for Chemical Energy Conversion, Max Planck Society;

/persons/resource/persons237637

Lubitz,  Wolfgang
Research Department Lubitz, Max Planck Institute for Chemical Energy Conversion, Max Planck Society;

/persons/resource/persons216826

Pantazis,  Dimitrios A.
Research Department Neese, Max Planck Institute for Chemical Energy Conversion, Max Planck Society;

/persons/resource/persons237557

Cox,  Nicholas
Research Department Lubitz, Max Planck Institute for Chemical Energy Conversion, Max Planck Society;

External Resource
No external resources are shared
Fulltext (restricted access)
There are currently no full texts shared for your IP range.
Fulltext (public)
There are no public fulltexts stored in PuRe
Supplementary Material (public)
There is no public supplementary material available
Citation

Krewald, V., Retegan, M., Neese, F., Lubitz, W., Pantazis, D. A., & Cox, N. (2016). Spin State as a Marker for the Structural Evolution of Nature’s Water-Splitting Catalyst. Inorganic Chemistry, 55(2), 488-501. doi:10.1021/acs.inorgchem.5b02578.


Cite as: https://hdl.handle.net/21.11116/0000-0007-45FF-D
Abstract
In transition-metal complexes, the geometric structure is intimately connected with the spin state arising from magnetic coupling between the paramagnetic ions. The tetramanganese–calcium cofactor that catalyzes biological water oxidation in photosystem II cycles through five catalytic intermediates, each of which adopts a specific geometric and electronic structure and is thus characterized by a specific spin state. Here, we review spin–structure correlations in Nature’s water-splitting catalyst. The catalytic cycle of the Mn4O5Ca cofactor can be described in terms of spin-dependent reactivity. The lower “inactive” S states of the catalyst, S0 and S1, are characterized by low-spin ground states, SGS = 1/2 and SGS = 0. This is connected to the “open cubane” topology of the inorganic core in these states. The S2 state exhibits structural and spin heterogeneity in the form of two interconvertible isomers and is identified as the spin–switching point of the catalytic cycle. The first S2 state form is an open cubane structure with a low-spin SGS = 1/2 ground state, whereas the other represents the first appearance of a closed cubane topology in the catalytic cycle that is associated with a higher-spin ground state of SGS = 5/2. It is only this higher-spin form of the S2 state that progresses to the “activated” S3 state of the catalyst. The structure of this final metastable catalytic state was resolved in a recent report, showing that all manganese ions are six-coordinate. The magnetic coupling is dominantly ferromagnetic, leading to a high-spin ground state of SGS = 3. The ability of the Mn4O5Ca cofactor to adopt two distinct structural and spin-state forms in the S2 state is critical for water binding in the S3 state, allowing spin-state crossing from the inactive, low-spin configuration of the catalyst to the activated, high-spin configuration. Here we describe how an understanding of the magnetic properties of the catalyst in all S states has allowed conclusions on the catalyst function to be reached. A summary of recent literature results is provided that constrains the sequence of molecular level events: catalyst/substrate deprotonation, manganese oxidation, and water molecule insertion.