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Ruthenium Complexes with Strongly Electron‐Donating Terpyridine Ligands: Effect of the Working Electrode on Electrochemical and Spectroelectrochemical Properties
Author(s) -
Klein Johannes,
Stuckmann Alexandra,
Sobottka Sebastian,
Suntrup Lisa,
van der Meer Margarethe,
Hommes Paul,
Reissig HansUlrich,
Sarkar Biprajit
Publication year - 2017
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.201701431
Subject(s) - terpyridine , electrochemistry , ruthenium , redox , supramolecular chemistry , chemistry , electrode , glassy carbon , working electrode , ligand (biochemistry) , crystallography , photochemistry , combinatorial chemistry , inorganic chemistry , cyclic voltammetry , metal , catalysis , crystal structure , organic chemistry , biochemistry , receptor
The combination of 2,2′:6′,2′′‐terpyridines (tpy) and Ru II is known to deliver molecular and supramolecular assemblies with remarkable properties. Here new Ru II complexes, with modified tpy ligands substituted with varying numbers of dimethlyamino groups, are presented. Electrochemistry shows that the incorporation of the strongly electron‐donating groups on the tpy ligands leads to a negative shift of the Ru II oxidation potential by close to 1 V. The reductive electrochemical responses are strongly dependent on the nature of the working electrode, with glassy carbon and gold working electrodes showing the best results. These observations led to the development of a modified Optically Transparent Thin Layer Electrochemical (OTTLE) cell, based on a gold working electrode. The use of UV/Vis/NIR spectroelectrochemical methods with that OTTLE cell, together with simulations of the cyclic voltammograms, allowed the characterization of four reduction steps in these complexes, the final two of which lead to bond activations at the ruthenium center. This observation is to the best of our knowledge unprecedented in coordinatively saturated complexes of type [Ru(tpy) 2 ] 2+ . The various redox states of the complexes were characterized by EPR spectroelectrochemistry and through DFT calculations. The results presented here establish these substituted tpy ligands as highly attractive ligands in coordination chemistry, and display the utility of a gold‐based OTTLE cell for spectroelectrochemical measurements.