Reversible Binding of Dioxygen to Ruthenium(II) Porphyrins
Farrell, N., David DolphinH., and James, B.R.
J. Am. Chem. Soc.
Solutions of porphyrin (H2L) complexes, RuL(MeCN)2, in MeCONMe2, DMF, or pyrrole, bind 1.0 mol of O2 per Ru reversibly at 20 oC and 1 atm pressure. The MeCN complexes are prepared by photolysis of the corresponding RuL(CO)(EtOH), complexes in MeCN. In PhMe solution, the O2 reaction leads only to a slow irreversible oxidation to Ru(III). Related complexes with more strongly coordinated axial ligands, such as pyridine and N-methylimidazole, also give only oxidation products. Electrolysis of the bisacetonitrile complex brings about a reversible 1-electron oxidation to give a Ru(III) cation.