High-valent ruthenium(IV) and -(VI) oxo complexes of octaethylporphyrin. Synthesis, spectroscopy, and reactivities

Abstract

Oxidation of [RuII(OEP)(CO)] [H2OEP = octaethylporphyrin] by m-chloroperoxybenzoic acid in methanol gave [RuVI(OEP)(O)2], isolated as air-stable diamagnetic purple solid (μeff ∼ 0 μB). [RuVI(OEP)(O)2] shows one intense IR band at 821 cm-1 assignable to vas(O=Ru=O) stretch. In CH2Cl2, it reacts with olefins to give epoxides and [RuIV(OEP)(OH)]2O in quantitative yields. In alcohols (ROH), the epoxidation reactions give [RuIV(OEP)O(ROH)], which readily dimerizes to [RuIV(OEP)(OH)]2O in noncoordinating solvents. [RuIV(OEP)O(ROH)] is paramagnetic with measured μeff of 3.1 μB. Its 1H NMR spectrum shows three broad singlets, the paramagnetic isotropic shifts of which vary inversely with temperature. The E° for the [RuIV(OEP)O(ROH)]/[RuIII(OEP)O(ROH)]- couple in CH2Cl2/py (py = pyridine) is -0.86 V vs Cp2Fe+/0. In CH2Cl2/py solution, [RuIV(OEP)O(ROH)] reacts with olefins to give [RuII(OEP)(py)2] and epoxides. © 1989 American Chemical Society.