Reduction potentials phosphorus

As is seen, in the NaPOs-NaCl system similar to Mo(V) and W(V) polyhedra of the same composition and structure are formed that predetermines possible similarity of their electrochemical behavior. Indeed, in the system studied the values of tungsten and molybdenum reduction potentials were proved to be almost identical and more positive as compared to the phosphorus reduction potential (Fig.4). In addition, solubility of molybdenum and tungsten trioxides was found to be fairly high and the binary system metaphosphate-sodium chloride rather low-melting. 

White phosphorus reduction. White phosphorus, and indeed sodium or potassium thiocyanate, are fast reducers. Chloroauric acid is boiled under reflux with white phosphorus (6) dissolved in diethylether. Boiling is continued until the solution turns from a brownish shade to red—this usually takes about 5 mm. This method produces gold particles m the smaller size range (2-12 nm) Accurate production of the particle size range is not easy, and, since the procedure is potentially highly dangerous, it is not commonly used... 

Electrochemical experiments on bidentate phosphorus ligands indicate that ligands with reduction potentials more positive than - IV (versus SCE) form long-lived 19-electron species with cobalt carbonyls, whereas ligands with more negative potentials form reactive species. For example, with a reduction potential of -0.7 V, bis(diphenylphosphino)maleic anhydride was expected to form a stable species with cobalt carbonyls, a prediction confirmed by its synthesis. ... 

Of the many published procedures for the synthesis of WCLt, the two most commonly employed methods are reduction of WCle with red phosphoras in a sealed tube, or reduction of WClg with W(CO>6 in refluxing chlorobenzene. The suitability of WCLj for some chemical uses is dependent on its preparative route because of associated impurities. For example, tungsten phosphides and phosphorus are potential contaminants in WCI4 that is derived from reduction with red phosphorus. Tungsten hexacarbonyl, W(CO)e, is an expensive reductant, toxic CO is liberated, and chlorobenzene can be difficult to remove. 

Akiba investigated the electrochemical behavior of a variety of phosphorus octaethylporphyrin derivatives all compounds showing a single reversible oxidation wave [91]. The absolute difference in potential between the first ring-centered oxidation and reduction varies from 2.19 to 2.36 V in dichloromethane. These values are within the range of the HOMO-LUMO gap observed for most metalloporphyrins. 

---