Synthesis, characterization, and reactivity of [Ru(bpy)(CH3CN)3(NO2)]PF6, a synthon for [Ru(bpy)(L3)NO2] complexes

We report a high yield, two-step synthesis of fac-Ru(bpy)(CH3CN)3NO2]PF6 from the known complex (p-cym)Ru(bpy)Cl]PF6 (p-cym = eta(6)-p-cymene). (p-cym)Ru(bpy)NO2]PF6 is prepared by reacting (p-cymene)Ru(bpy)Cl]PF6 with AgNO3/KNO2 or AgNO2. The 15NO2 analogue is prepared using K15NO2. Displacement of p-cymene from (p-cym)Ru(bpy)NO2]PF6 by acetonitrile gives Ru(bpy)(CH3CN)3NO2]PF6. The new complexes (p-cym)Ru(bpy)NO2]PF6 and fac-Ru(bpy)(CH3CN)3NO2]PF6 have been fully characterized by 1H and 15N NMR, IR, elemental analysis, and single-crystal structure determination. Reaction of Ru(bpy)(CH3CN)3NO2]PF6 with the appropriate ligands gives the new complexes Ru(bpy)(Tp)NO2] (Tp = HB(pz)3-, pz = 1-pyrazolyl), Ru(bpy)(Tpm)NO2]PF6 (Tpm = HC(pz)3), and the previously prepared Ru(bpy)(trpy)NO2]PF6 (trpy = 2,2',6',2' '-terpyridine). Reaction of the nitro complexes with HPF6 gives the new nitrosyl complexes Ru(bpy)TpNO]PF6]2 and Ru(bpy)(Tpm)NO]PF6]3. All complexes were prepared with 15N-labeled nitro or nitrosyl groups. The nitro and nitrosyl complexes were characterized by 1H and 15N NMR and IR spectroscopy, elemental analysis, cyclic voltammetry, and single-crystal structure determination for Ru(bpy)TpNO]PF6]2. For the nitro complexes, a linear correlation is observed between the nitro 15N NMR chemical shift and 1/nu(asym), where nu(asym) is the asymmetric stretching frequency of the nitro group.