Structural chemistry of peroxo compounds of group VI transition metals: I. Peroxo complexes of chromium (a review)

The specific features revealed in the structure of the d3 Cr(III), d2 Cr(IV), d1Cr(V), and d0 Cr(VI) peroxo complexes with the ratios M:O2 = 1:1, 1:2, and 1:4 are considered. It is noted that, in eleven compounds of the general formula Cr(O2)nOmAp (n = 1, 2, 4; m = 0, 1; p = 0-4), the metal atoms can be in four oxidations states: +3 (d3), +4 (d4), +5 (d1), and +6 (d0). This property distinguishes chromium peroxo compounds from molybdenum and tungsten dioxygen complexes, which, with one exception, are represented by the d0M(VI) compounds