Preparation, Characterization, Electrochemistry, and Infrared Spectroelectrochemistry of Ruthenium Nitrosyl Porphyrins Containing η1-O Bonded Axial Carboxylates

The synthesis, characterization and redox behavior of eight low-spin nitrosyl carboxylate compounds (por)Ru(NO)(η1-OC(=O)R) (por = T(p-OMe)PP: R = Me (1), i-Pr (2), t-Bu (3), p-C6H4NO2 (4), Fc (5), CF3 (8); por = TTP: R = Fc (6)) and (T(p-OMe)PP)Ru(NO)(OC6HF4) (7) are reported. The compounds are moderately stable in air as solids. Their IR (KBr) spectral data show ʋNO\u27s in the 1839-1861 range cm-1. The X-ray crystal structures of compounds 1, 2, 5-7, and 8 have been determined, and reveal linear RuNO linkages for these formally {RuNO}6 complexes. The redox behavior of the compounds at a Pt working electrode were studied in CH2Cl2 with NBu4PF6 as supporting electrolyte. The compounds display reversible first oxidations. IR spectroelectrochemistry of compounds 1-4, 7 and 8 revealed porphyrin centered oxidations, whereas the ferrocenylcarboxylate compounds revealed first oxidations at the ferrocenyl moiety followed by second oxidations at the porphyrin macrocycles. Reductions of these compounds are accompanied by loss of the axial ligands