Detection of the EPR Spectra of NO^• in Ruthenium(II) Complexes

Abstract

The EPR of NO. can be detected in the liquid and solid states when crystal fields are sufficient to remove the axial symmetry and separate the (pi*)x and (pi*)y orbitals by a few hundred reciprocal centimeters. The theory of the EPR spin Hamiltonian of bound NO. is reviewed, further developed, and then applied to the observed frozen-liquid spectra of NO. bound to Ru(II) obtained from RuIINO+ complexes by reduction. Comparisons to earlier reports on the observation of the EPR spectra of NO. are made.

Ruthenium Tetraammines as a Model of Nitric Oxide Donor Compounds

“…Considering the structural and chemical similarities among all title complexes, such behavior is expected to be general for the whole series. A similar EPR spectrum [28] was also observed for the oneelectron reduced species of trans-[RuPP (Cl)…”

“…Thus, the one-electron reduction of these complexes is expected to generate [Ru II NO 0 ] species. Indeed, the coordinated NO radical have been detected through electron paramagnetic-resonance spectroscopy [28] for the reduced form of the trans-…”

Synthesis, Spectra and Electrochemistry of Dinitro-bis-{1-alkyl-2-(arylazo) imidazole} Ruthenium(II). Nitro-nitroso Derivatives and Reactivity of the Electrophilic {Ru-NO}6System

“…The similar complex with diimine system, [Ru(NO 2 )(py)(bpy) 2 ] + displays the Ru(III)/Ru(II) couple at $1.0 V vs SCE [20,21]. The stronger p-acidic nature of RaaiR¢ compared to adiimine system leads to better stabilisation of Ru(II) in the present series of complexes.…”

Reatividade química e fotoquímica de complexos nitrosilos de rutênio do tipo [Ru(terpy)(L)NO]n+

“…amplamente investigados por Franco e colaboradores (GORELSKY et al, 2000;TOLEDO et al, 2005;BORGES et al, 1998 , 4, 8, 11-tetraazaciclotetradecano (LANG et al, 2000;McGARVEY et al, 2000), e trans-[RuCl(imcyclen)(NO)] 2+ (FERREIRA et al, 2004).…”