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A Gas‐Phase Ca n Mn 4− n O 4 + Cluster Model for the Oxygen‐Evolving Complex of Photosystem II
Author(s) -
Mauthe Silvia,
Fleischer Irene,
Bernhardt Thorsten M.,
Lang Sandra M.,
Barnett Robert N.,
Landman Uzi
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201903738
Subject(s) - chemistry , deprotonation , density functional theory , cluster (spacecraft) , photosystem ii , reactivity (psychology) , molecule , hydroxylation , ligand (biochemistry) , ion , crystallography , photochemistry , stereochemistry , computational chemistry , medicine , biochemistry , photosynthesis , alternative medicine , enzyme , organic chemistry , receptor , pathology , computer science , programming language
One of the fundamental processes in nature, the oxidation of water, is catalyzed by a small CaMn 3 O 4 ⋅MnO cluster located in photosystem II (PS II). Now, the first successful preparation of a series of isolated ligand‐free tetrameric Ca n Mn 4− n O 4 + ( n =0–4) cluster ions is reported, which are employed as structural models for the catalytically active site of PS II. Gas‐phase reactivity experiments with D 2 O and H 2 18 O in an ion trap reveal the facile deprotonation of multiple water molecules via hydroxylation of the cluster oxo bridges for all investigated clusters. However, only the mono‐calcium cluster CaMn 3 O 4 + is observed to oxidize water via elimination of hydrogen peroxide. First‐principles density functional theory (DFT) calculations elucidate mechanistic details of the deprotonation and oxidation reactions mediated by CaMn 3 O 4 + as well as the role of calcium.