Ruthenium Tetraammines as a Model of Nitric Oxide Donor Compounds

• Published in: European journal of inorganic chemistry 2004-05, Vol.2004 (9), p.1879-1885
• Main Authors: Toledo, José Carlos, Silva, Hildo A. S., Scarpellini, Marciela, Mori, Vânia, Camargo, Ademir J., Bertotti, Mauro, Franco, Douglas W.
• Format: Article
• Language: English
• Subjects: N-heterocyclic ligands; Nitric oxide; NO donor; Ruthenium
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.200300683

The nitric oxide liberation from trans‐[Ru(NH3)4(L)(NO)]3+ (where L = py, 4‐pic, isn, nic, L‐His, 4‐Clpy, imN) after one‐electron‐chemical or electrochemical reduction was investigated through spectroscopic and electrochemical techniques, reaction‐product analysis and quantum‐mechanic calculations. These complexes can be formally viewed as a RuII(NO+) species and the reduction site is located on the NO ligand. The E° for the trans‐[RuII(NH3)4(L)(NO+)]3+/trans‐[RuII(NH3)4(L)(NO)]2+ redox process ranges from 0.072 V vs. NHE (nic) to −0.118 V vs. NHE (imN). The specific rate constants for NO dissociation from trans‐[RuII(NH3)4(L)(NO)]2+, evaluated through double‐step chronoamperometry, range from 0.025 s−1 (nic) to 0.160 s−1 (ImN) at 25 °C. The [RuIINO+/RuIINO0] redox potential and the specific rate constant (k‐NO),key steps for designing nitrosyl complexes as NO‐donor drug prototypes, proved to be controlled by a judicious choice of the ligand (L) trans to NO. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)