Ruthenium Tetraammines as a Model of Nitric Oxide Donor Compounds

✍ Scribed by José Carlos Toledo; Hildo A. S. Silva; Marciela Scarpellini; Vânia Mori; Ademir J. Camargo; Mauro Bertotti; Douglas W. Franco

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 147 KB
• Volume: 2004
• Category: Article
• ISSN: 1434-1948
• DOI: 10.1002/ejic.200300683

✦ Synopsis

Abstract

The nitric oxide liberation from trans‐[Ru(NH~3~)~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 Ru^II^(NO^+^) species and the reduction site is located on the NO ligand. The E° for the trans‐[Ru^II^(NH~3~)~4~(L)(NO^+^)]^3+^/trans‐[Ru^II^(NH~3~)~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‐[Ru^II^(NH~3~)~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 [Ru^II^NO^+^/Ru^II^NO^0^] 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)