Significant O–H Bond Weakening in CpMn(CO)2(CH3OH): Evidence for the Generation of the CpMn(CO)2(CH3O) Radical upon H Atom Abstraction by O2

The UV–visible photolysis of CpMn(CO)3 in methanol generates CpMn(CO)2(CH3OH), which upon H atom abstraction using either O2, dpph, or H2O2 gives the CpMn(CO)2(CH3O) radical complex. The radical with a lifetime of 10 to 20 min has been mainly characterized using FTIR and ESR spectroscopy and chemical oxidation studies. Together with density functional theory calculations, it is shown that the O–H bond is significantly weakened in the CpMn(CO)2(CH3OH) complex compared to free methanol. NBO spin density analysis suggests that the bond cleavage is facilitated by the formation of the CpMn(CO)2(CH3O) radical in which the electron spin is localized at the metal center rather than at the oxygen atom.