“…Early work brought evidence for this spectroscopically, [1,2] and in the late 1990s the first chromium(IV) oxo complexes were structurally characterized. [3,4] Within the last years it has been shown, in particular by Nam and Theopold, that molecular chromium(II) centers, ligated by nitrogen donors, in contact with dioxygen formed reactive species featuring superoxido, peroxido, and oxido ligands. [5][6][7][8][9] We believed that siloxide surroundings could lead to novel reactivity in this regard, as chromium(II) sites embedded in a silica matrix are known to have rather special electronic properties, that therefore guarantee the activity of the Phillips catalyst [10,11] employed for the industrial polymerization of ethylene.…”