A stable manganese(V)-oxo corrolazine complex.

Abstract

The synthesis and characterization of an oxomanganese(V) corrolazine, (TBP)8(Cz)Mn(V)O (2), are reported. This remarkably stable high-valent complex is obtained from the stoichiometric reaction of (TBP)8(Cz)Mn(III) (1) with m-CPBA and is easily purified by standard chromatographic methods on silica gel at room temperature. Complex 2 exhibits a diamagnetic 1H NMR spectrum indicative of a low-spin d2 Mn(V)O species. LDI-TOFMS of 2 shows the predicted isotopic envelope at m/z 1426.8. This envelope shifts to higher mass as expected after the facile exchange of the terminal oxo group with H218O. The resonance Raman spectrum of 2 either in solution or in the solid state shows a strongly enhanced Raman band for the stretching mode of the Mn-oxo bond, which also shifts as expected upon 18O substitution: 2(16O), 979 cm-1; 2(18O), 938 cm-1 (in CH2Cl2). Initial reactivity studies show that 2 rapidly transfers the terminal oxo ligand to PPh3, resulting in the quantitative formation of OPPh3 and concomitant reduction of 2 back to 1. Complex 2 is the first example of an oxomanganese(V)-porphyrinoid complex that can be isolated at room temperature.