Metal-dioxygen complexes bond lengths

This strategy has deliberately avoided the superoxo/peroxo dichotomy. The extent of electron transfer to dioxygen in these adducts is difficult to assess and is a subject which remains controversial. However, it is convenient to divide the wealth of metal-dioxygen complexes into superoxo-type and peroxo-type upon the basis of structural data from the point of view of ease of discussion. We have done this purely on the basis of bond lengths and IR data and do not intend this to be interpreted as a measurement of the extent of electron transfer from the metal to the dioxygen ligand. 

Bond Lengths in Metal-Dioxygen Complexes and Metal Peroxides... 

Table 1 O—O stretching frequencies and bond lengths of dioxygen and its metal complexes.

Table 2 lists structural data for some representative peroxo complexes. It is interesting to note that for the majority of these complexes there is very little variation in 0-0 bond lengths despite differences in metal, ligands, valence state and structure. Fourteen of the twenty-two complexes listed in Table 2 have 0-0 bond lengths between 1.40 and 1.49 A. In fact, the 0-0 bond length is not greatly affected by whether the dioxygen is coordinated to one or two metal centers [3]. The most... 

X0 complexes [36], Moreover, inconsistencies became apparent as more data accumulated on other monomeric metal-dioxygen species. For instance, the 0-0 bond lengths in [CoTp (j/ -02)] and [Cu(II)Tp ( -02)] are nearly identical, but their v(O-O) differ by around 150 cm. In addition, a DFT study predicted that the 0-0 bond length in [CoTp (j/ -02)] should be longer by almost 0.1 A. This same study also found a linear correlation between the v(O-O) and 0-0 bond lengths for adducts - [CoTp (// -02)] was one of... 

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