Manganese complexes visible spectra

Figure 7.2.7 A salicylaldimine-manganese(III) complex dimerizes and is protonated. The visible spectrum shows a small charge-transfer band close to 600 nm belonging to the dimer. Irradiation with visible light produces some molecular oxygen. Its formation may occur in the way indicated by the given stoichiometric equation. (From Ashmawy et al., 1985, and Awad and Anderson, 1989.)...

The energy difference between the upper and lower sheets is 4Ejj at the position of the minimum po. For copper(II) [5], chromium(II) [6] and manganese(III) [7] complexes, the transition can be readily observed by optical spectroscopy, falling in the near infrared/visible region of the electromagnetic spectrum. 

When manganese(iii) is mixed with the [VO(dtpa)] " ion in an acetate buffer medium, a reaction occurs to form a complex that retains the characteristic visible absorptions of Mn i and but slowly bleaches to Mn and V. The disappearance of and formation of Mn can also be detected by the e.s.r. spectrum. It is proposed that the initial product is the dinuclear complex (5), which slowly undergoes electron transfer and rearrangement to form (6). 

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