Effect of second-sphere coordination 13. Consideration of factors affecting adduct formation of ruthenium–ammine complexes with crown ethers based on the stability constants

Effect of second-sphere coordination 14. Adduct formation of ruthenium complexes with protic ligands of different types

“…Upon adduct formation with 15C5, the stability of hydrogen bonding is greater at the ammine sites than at the imine site, even though the hydrogen bond at the imine is stronger than those at the ammine sites. The effect of steric compatibility is superior to that of Dd in this case though steric compatibility between crown ether and protic ligand and Dd affect the stability of the crown ether adduct [13].…”

“…Ruthenium complexes with protic ligands form adducts with crown ethers through hydrogen bonding, and several factors affect the adduct formation [12][13][14][15]. In the case of the complexes containing protic ligands of different configurations, the steric compatibility may preferentially or selectively affect hydrogen bonding depending on the ring size of the crown ether.…”

“…Upon adduct formation, hydrogen bonding was established at the qdiH + site of high p-electronacceptor ability as well as at the ammine ligand. The change in redox potential upon adduct formation of ruthenium-ammine complexes with crown ethers is affected by the strength of the hydrogen bonds formed and the p-electronacceptor ability of the aromatic ligand [12,13]. The ligand qdiH + in the complex has strong p-electronacceptor ability.…”

“…This change in redox potential is akin to that caused by displacement of a ligand from the complex. The change in redox potential is due to several factors, which have been elucidated by determining stability constants of crown ether adducts with rutheniumammine complexes [13]. The acidity of protic ligands and the steric compatibility between a protic ligand and a crown ether may be among the most important factors for selective interaction with a certain protic ligand site of the complex.…”

“…Furthermore, qdiH + shows better compatibility with crown ethers, 18-crown-6 ether or 15-crown-5 ether. Thus, it was of interest to determine the change in redox potential caused by hydrogen bonding to qdiH + because of its stronger p-electron acceptor ability [13].…”