trans-[Ru(NO)(NH_3)P(O~-)(OEt)_2]~(2+): A new and robust NO/HNO-donor in aqueous media

摘要

This study describes the synthesis and reactivity in aqueous media of a new potential NO/HNO-donor: trans-[Ru(NO)(NH_3)_4P(O~-)(OEt)_2](PF_6)_2. This compound exhibits a remarkable robustness over a wide range of pH relative to other similar ruthenium phosphorus nitrosyl complexes. At pH 3.0 and 25 ℃, trans-[Ru(NO)(NH_3)_4P(O~-)(OEt)_2](PF_6)_2 decays, yielding free diethyl phosphite with a half-life of 9 days(k = 8.9 × 10~(-7) s~(-1)). At pH 7.5 and 25 ℃, this complex is competitively consumed by diethyl phosphite dissociation (k = 5.15 × 10~(-5) s~(-1)) and nucleophilic attack at the nitrosyl group (k = 7.25 × 10~(-5) s~(-1)). Nevertheless, the trans-[Ru(NO)(NH_3)_4P(O~-)(OEt)_2](PF_6)_2 exhibits a half-life of 1.5 h (pH 7.5 and 25 ℃) for delivering NO/HNO by electrochemical activation at potentials of-0.50 and-0.80 V versus SCE. The NO liberation from trans-[Ru(NO)(NH_3)_4P(O~-)(OEt)_2]~+ ion occurs with k_(-NO) = 0.24 ± 0.01 s~(-1), and electrochemical data indicate that k_(-HNO)k_(-NO).