Oxygen, electronic spectra

Solutions of CrCl2-2CH3CN and the wet solid are extremely sensitive to oxygen. When dried, however, the complex remains unchanged in air for several minutes before oxidation becomes apparent. It is virtually insoluble in acetonitrile but quite soluble in ethanol. The room-temperature magnetic moment (4.8 B.M.) and electronic spectrum are consistent with a high-spin distorted octahedral Cr2+ ion.15... 

The electronic spectrum (36) of the pol5uner is dominated by a very broad ultraviolet band, with shoulders at 280 and 470 m/t, which tails into the visible region and is responsible for the deep brown color of the polymer. Very weak crystal field excitations are found at 640 and 880 m. From the latter transition one can estimate that for high-spin Fe +, Dq = 1100 cm i. This value is typical of Fe3+ in octahedral coordination with oxygen ligands, but the X-ray evidence (see below) indicates that the coordination is tetrahedral, so that Dq seems anomalously high. However, the coordination symmetry is actually lower than tetrahedral, since both hydroxide and oxide ligands are involved. 

Figure 2.11 Potential energy diagrams for molecular oxygen electronic energy states and the absorption spectrum of oxygen molecule.

Fig. 36. Conversion electron spectrum of an iron film after treatment in oxygen at 620 K for 5 min. Figure according to Simmons et al. 235).

Figure 6. Sulfur 2p electron spectrum from wool yarn exposed to oxygen plasma (top) and to a nitrogen plasma (bottom).

Figure 39. Electron spectrum from phosphine anchored rhodium containing catalyst after 30-min exposure to oxygen plasma etching.

---