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Three‐Way Cooperativity in d 8 Metal Complexes with Ligands Displaying Chemical and Redox Non‐Innocence
Author(s) -
Deibel Naina,
Hohloch Stephan,
Schweinfurth David,
Weisser Fritz,
Grupp Anita,
Sarkar Biprajit
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201403276
Subject(s) - protonation , chemistry , electron transfer , redox , proton , proton coupled electron transfer , metal , ligand (biochemistry) , cooperativity , non innocent ligand , photochemistry , inorganic chemistry , organic chemistry , ion , biochemistry , physics , receptor , quantum mechanics
Reversible proton‐ and electron‐transfer steps are crucial for various chemical transformations. The electron‐reservoir behavior of redox non‐innocent ligands and the proton‐reservoir behavior of chemically non‐innocent ligands can be cooperatively utilized for substrate bond activation. Although site‐decoupled proton‐ and electron‐transfer steps are often found in enzymatic systems, generating model metal complexes with these properties remains challenging. To tackle this issue, we present herein complexes [(cod −H )M(μ‐L 2− ) M (cod −H )] (M=Pt II , [ 1 ] or Pd II , [ 2 ], cod=1,5‐cyclooctadiene, H 2 L=2,5‐di‐[2,6‐(diisopropyl)anilino]‐1,4‐benzoquinone), in which cod acts as a proton reservoir, and L 2− as an electron reservoir. Protonation of [ 2 ] leads to an unusual tetranuclear complex. However, [ 1 ] can be stepwise reversibly protonated with up to two protons on the cod −H ligands, and the protonated forms can be stepwise reversibly reduced with up to two electrons on the L 2− ligand. The doubly protonated form of [ 1 ] is also shown to react with OMe − leading to an activation of the cod ligands. The site‐decoupled proton and electron reservoir sources work in tandem in a three‐way cooperative process that results in the transfer of two electrons and two protons to a substrate leading to its double reduction and protonation. These results will possibly provide new insights into developing catalysts for multiple proton‐ and electron‐transfer reactions by using metal complexes of non‐innocent ligands.