title: Unexpected NO transfer reaction between trans-[Ru(II)(NO+)(NH3)4(L)]3+ and Fe(III) species: observation of a heterobimetallic NO-bridged intermediate.
abstract: The reaction between trans-[Ru(II)(NO(+))(NH3)4(L)](3+), L = ImN, IsN, Nic, P(OMe)3, P(OEt)3, and P(OH)(OEt)2, and the Fe(III) species [Fe(III)(TPPS)], metmyoglobin, and hemoglobin was monitored by UV-vis, EPR, and electrochemical techniques (DPV, CV). No reaction was observed when L = ImN, IsN, Nic, and P(OH)(OEt)2. However, when L = P(OMe)3 and P(OEt)3, the reaction was quantitative and the products were trans-[Ru(III)(H2O)(NH3)4(P(OR)3)](3+) and [Fe(II)(NO(+))] species. Reaction kinetics data and DFT calculations suggest a two-step reaction mechanism with the initial formation of a bridged [Ru-(μNO)-Fe] intermediate, which was confirmed through electrochemical techniques (E(0)' = -0.47 V vs NHE). The calculated specific rate constant values for the reaction were in the ranges k1 = 1.1 to 7.7 L mol(-1) s(-1) and k2 = 2.4 × 10(-3) to 11.4 × 10(-3) s(-1) for L = P(OMe)3 and P(OEt)3. The oxidation of the ruthenium center (Ru(II) to Ru(III)) containing the nitrosonium ligand suggests that NO can act as an electron transfer bridge between the two metal centers.
authors.affiliation: Instituto de Química de São Carlos, Universidade de São Paulo , Avenida Trab. São-Carlense 400, São Carlos, SP, Brazil.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Metzker
authors.forename: Pietro P
authors.initials: PP
authors.lastname: Lopes
authors.forename: Augusto C H
authors.initials: AC
authors.lastname: da Silva
authors.forename: Sebastiao C
authors.initials: SC
authors.lastname: da Silva
authors.forename: Douglas W
authors.initials: DW
authors.lastname: Franco
mesh_terms: D004563:Electrochemistry; D004578:Electron Spin Resonance Spectroscopy; D005290:Ferric Compounds / Q000737:chemistry*; D007700:Kinetics; D008786:Metmyoglobin / Q000737:chemistry; D009569:Nitric Oxide / Q000737:chemistry*; D017975:Ruthenium Compounds / Q000737:chemistry*
chemical_list: D005290:Ferric Compounds; D017975:Ruthenium Compounds; D008786:Metmyoglobin; D009569:Nitric Oxide