Selenium, energy levels

Tamao K, Miyaura N (2002) Introduction to Cross-Coupling Reactions. 219 1-9 Tanaka M (2003) Homogeneous Catalysis for H-P Bond Addition Reactions. 232 25-54 Tanner PA (2004) Spectra, Energy Levels and Energy Transfer in High Symmetry Lanthanide Compounds. 241 167-278 Tantillo DJ, see Houk KN (2004) 238 1-22 ten Holte P, see Zwanenburg B (2001) 216 93-124 Thiem J, see Werschkun B (2001) 215 293-325 Thorp HH (2004) Electrocatalytic DNA Oxidation. 237 159-181 Thutewohl M, see Waldmann H (2000) 211 117-130 Tichkowsky I, see Idee J-M (2002) 222 151-171 Tiecco M (2000) Electrophilic Selenium, Selenocyclizations. 208 7-54... 

Fig. 2.5. Schematic electronic energy level diagram for selenium showing, from left to right, valence electron states of the free atom, splittings due to interactions with a second atom, and energy bands in the condensed phases of selenium. The p-electron bonding and antibonding states are denoted

Fig. 2.5 Schematic electronic energy level diagram for selenium showing valence electron states of the free atom, splittings due to interactions with a second atom, and energy bands in the condensed phases of selenium. 19...

The relative energy levels and processes occurring in amorphous selenium and the PNVC/TNF system (from Mott and Emerald 1). HOMO, highest occupied molecular orbital LEMO lowest empty molecular orbital., Electron o, hole... 

Nutritional status can also influence the toxic potency of carbon tetrachloride. Animal studies have clearly demonstrated that brief fasting or consumption of diets low in antioxidants (vitamin E, selenium, methionine) can lead to increased carbon tetrachloride hepatotoxicity. The same may be true for humans, although this is not known for certain. Another aspect of nutritional status affecting carbon tetrachloride toxicity is hepatic energy status. Hepatic ATP levels might influence the ultimate outcome of toxicity (low levels may inhibit recovery mechanisms). 

As in the case of sulphur, XPS was most suitable for studying electron transport on protein bound selenium, especially in those reactions where no magnetic properties or electronic transitions can be measured The chemical shift of the binding energy values of the Se 3 d levels can reach up to 7.5 eV (Table 3). This large shift allows the assignment of the chemical nature of selenium and selenopeptides to be made Measurements of selenotrisulphides, the well known reaction products between selenite and thiols, deserved special attention (Table 4). 

The crown-shaped molecule Se8 has long been known to crystallize in two monoclinic lattices termed a- and jS-Se8, respectively (see Table II). Crystals of various sizes have been obtained from CS2 solutions prepared by dissolution of either red amorphous Se (22) or of vitreous selenium in CS2 and subsequent cooling or evaporation of the solvent (3a,b, 4a, 5). Red amorphous Se is readily soluble in CS2, but since both vitreous and red amorphous Se do not contain more than small amounts of Se8, the dissolution must be accompanied by a chemical interconversion. It has, however, been reported (26) that the dissolution of red amorphous Se in CS2 requires illumination with photons of energies in excess of 2.3 eV, ambient room light levels being sufficient. 

DOE. 1987. A cathodic stripping technique for the determination of trace levels of arsenic and selenium in waste, organic, and environmental samples. Report to U.S. Department of Energy by Martin Marietta Energy Systems, Inc., Oak Ridge, TN. DOE K/PS-5078. DE88-002257. 

The gas-phase tautomeric equilibrium of the selenium analog, 2,4-diselenouracil 171 (X = Se), was studied at the MP2 level of theory with a basis set of DZP quality. The relative energies, estimated at the MP4(SDQ) level, provided the same order of stability, predicted for 2,4-dithiouracil by the ab initio methods. The di(hydroselenyl) tautomer 171b (X = Se) was found to be less stable than diselenone tautomer 171a by 8.1 kcal/mol (96JST(388)237). 

---