Related Experiment Video
Updated: Jul 13, 2025
The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes
Published on: April 10, 2015
Configurationally Nonselective Aquation of a Mononuclear Ru(II) Chloro Complex to Aquo Complex Isomers with
Yuta Tsubonouchi1, Keisuke Inaba1, Norihisa Hoshino1
1Department of Materials Science and Technology, Faculty of Engineering, Niigata University, 8050 Ikarashi-2, Niigata 950-2181, Japan.
Abstract:
distal-[Ru(EtOtpy)(pynp)Cl]+ (d-EtO1Cl) (EtOtpy = 4'-ethoxy-2,2':6',2″-terpyridine, pynp = 2-(2-pyridyl)-1,8-naphthyridine), and distal/proximal-[Ru(EtOtpy)(pynp)OH2]2+ (d/p-EtO1HO) complexes were newly synthesized to investigate the synergistic influence of the geometric configuration coupled with substituent introduction of an ethoxy (EtO) group on the physicochemical properties and reactions of the Ru(II) complexes. Configurationally nonselective aquation of d-EtO1Cl was uniquely observed to form d/p-EtO1HO isomers in water, in contrast to configurationally selective aquation of distal-[Ru(tpy)(pynp)Cl]+ (d-1Cl, tpy = 2,2':6',2″-terpyridine) without the EtO group [Yamazaki, H. . J. Am. Chem. Soc. 2011, 133, 8846-8849].The kinetic profiles of the aquation reactions of d-EtO1Cl were well analyzed using a sequential reversible reaction model assuming the reversible interconversion between d/p-EtO1HO isomers via d-EtO1Cl. The observed equilibrium constant (Kiso) of isomerization between p/d-EtO1HO was calculated from the kinetic analysis as Kiso = 0.45, which is consistent with the final concentration ratio (1:0.43) of p/d-EtO1HO generated in the aquation reaction of d-EtO1Cl. The irreversible photoisomerization from d-EtO1HO to p-EtO1HO was observed in water with an internal quantum yield (Φ) of 0.44% at 520 nm. Electrochemical measurements showed that d-EtO1HO undergoes a 2-step oxidation reaction of 1H+-coupled 1e- processes of RuII-OH2/RuIII-OH and RuIII-OH/RuIV═O at pH 1.3-9.7, whereas p-EtO1HO undergoes a 1-step oxidation reaction of a 2H+-coupled 2e- process of RuII-OH2/RuIV═O in the pH range of 1.8-11.5. Any redox potential of d/p-EtO1HO isomers was decreased by the electro-donating EtO substitution, compared with distal/proximal-[Ru(tpy)(pynp)OH2]2+ (d/p-1HO). The turnover frequency (kO = 1.7 × 10-2 s-1) of d-EtO1HO for water oxidation catalysis is higher than that (3.5 × 10-4 s-1) of p-EtO1HO by a factor of 48.6. The kO value (1.7 × 10-2 s-1) for d-EtO1HO is 4.5-fold higher than those of d-1HO (3.8 × 10-3 s-1). The higher kO value of d-EtO1HO compared with d-1HO could be explained by the fast oxidation rate from RuIV═O to RuV═O involved in the rate-determining step due to the electron-donating EtO group.
More Related Videos
Related Concept Videos
01:26Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
02:17Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
02:34Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
01:25Radical Anti-Markovnikov Addition to Alkenes: Overview
02:34Structural Isomerism
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...