Selenides of phosphorus

Five selenides of phosphorus are known, viz. P4Se, P2Se, P4Se3, P2Se3 and P2Se5. 

Sulphoselenides.—When the selenides of phosphorus are melted with sulphur, products are obtained which have the composition P4SSe2 (m.pt. 225° to 230° C.) and P4S2Se (m.pt. 190° to 200° C.).s ... 

A"-Ray structure determinations (see Chapter 11 for details) have been reported for triphenylphosphine oxide, tri-o-tolylphosphine oxide, sulphide, and selenide, and for cw-2,2,3,4,4-pentamethyl-l-phenylphos-phetan-1-oxide (5). Electron spectroscopic studies of phosphorus oxychloride and thiophosphoryl chloride in the gaseous state, and n.m.r., i.r., and u.v. spectra of phosphine sulphides have appeared. Dipole moments have been used to define the stereochemistry of 2-cyanoethylphosphine oxides, such as (6), which is shown in its preferred conformation. 

The analogous selenium and tellurium species are best formed directly as their alkali-metal or ammonium salts, since the acids themselves tend to be much more unstable towards decomposition than the dithio-phosphorus acids, and are hence difficult to store and handle. Diselenophosphates can be prepared from refluxing a suspension of phosphorus(V) selenide in alcohol followed by treatment with potassium hydroxide or ammonia gas to give the... 

Thiotraamidophosphoric acids (35) are isoelectronic with phosphoric acids and were initially reported from the reaction of phosphorus pentasulfide with primary amines at high temperatures.62 Subsequently, an improved synthesis for 35 with increased yields and milder conditions has been reported involving the room temperature reaction of thiophosphoryl chloride and primary amines (Equation 50).63 The most convenient route to the analogous selenium derivatives SeP(NHPh)3 is from the oxidation of P(NHPh)3 with elemental selenium (Equation 51).63 Also isoelectronic with phosphoric acids are dithio wamido-phosphoric acids (36), which can be prepared from the reaction of phosphorus pentasulfide with an excess of primary amine at 30°C in toluene (Equation 52).62 The selenium derivatives of 36 can be prepared in a similar reaction from phosphorus (V) selenide, although due to their increased acidity... 

Diselenophosphates have been much less investigated than the analogous dithiophosphates, but some interesting chemistry was revealed. The reactions of phosphorus(V) selenide, P2Se5, with alcohols and phenols produce diseleno-phosphoric acid diesters, (RO)2P(Se)SeH, the parent compounds of di-selenophosphato anionic ligands. The free acids are not stable and should be immediately converted to metal salts or complexes. 

Further examples of deoxygenation of epoxides by phosphine sulphides or selenides have appeared,41 as shown in Scheme 6 for simple epoxides (50). Incorporation of phosphorus into a five-membered ring appears to be responsible for the relatively rapid deoxygenations by the phosphole and A3-phospholen derivatives.41... 

Diselenophosphate complexes are prepared from the interaction of metal salts and complexes with appropriate diselenophosphoric acid or its salt. The acids are obtained from the reaction of phosphorus(V) selenide with alcohols 229). The preparation of phosphorus(V) selenide and its reactions with alcohols 229) and amines 22°) have been described and a variety of complexes reported (Table 4). The biological activity of these compounds does not seem to have described but the exercise of extreme caution when handling these materials is recommended. Zingaro and his coworkers 229-232) thoroughly characterized the thermal and spectroscopic properties of a number of compounds. 

Many metallic selenides yield the gas when treated with dilute mineral acids. For example, when aluminium or magnesium selenide is dropped slowly into the acid a continuous stream of hydrogen selenide is generated, which can be dried by means of phosphorus pentoxide. If required in a high degree of purity, the dried gas can be liquefied, e.g. by means of a mixture of ether and solid carbon dioxide, and obtained pure by re-vaporisation.6... 

Selenium monochloride behaves as a strong chlorinating agent towards metals, metallic selenides and hydrocarbons.3 Phosphorus displaces selenium from the chloride with formation of phosphorus trichloride.4 Chlorine converts it into the tetrachloride. 

Baudrimont7 obtained the tetrachloride by the action of phosphorus pentachloride vapour on lead selenide. 

By the addition of iodine to a solution of phosphorus selenide, P4Se3, in carbon disulphide Mai5 lias obtained as a solid substance, tetraphosphorus di-iodide triselenide, PJ Sej, which on rapid heating melts at 154° to 155° C. 

Phosphorus Monoselenide, P2Se, may be obtained by heating one atomic proportion of selenium with two atomic proportions of phosphorus in a current of hydrogen. It is formed with incandescence as a clear red solid, which is combustible and slightly soluble in carbon disulphide. It is decomposed by boiling alkalis witli liberation of phosphine. With metal selenides it forms double selenides. 

Phosphorus Triselenide or Phosphorous Selenide, P2Se3.— This compound may be obtained by heating together phosphorus and selenium in the requisite atomic proportions. The reaction is accompanied by a great evolution of heat. The product is a ruby-red solid, which is combustible on heating. It is insoluble in carbon disulphide. With metal selenides it forms double selenides of the typeP2Se3.2MSe.2... 

Selenophosphates and Oxyselenophosphates.—By the action of phosphorus pentaselenide on aqueous solutions of the selenides of... 

Diphenyl-EGaAS -dithia-O-selenapentalene has been prepared by two different methods (a) reaction of phosphorus pentaselenide with2-phenyl-(5-phenyl-l,2-dithiol-3-ylidene)ethanal86 and (b) reaction of sodium hydrogen selenide with the Vilsmeier salt (70).49... 

As was the case for the basic hydrolysis of phosphorus, tracing the path of basic hydrolysis of the chalcogens is a formidable task the reactions are two-phase reactions and proceed through a series of steps of which the first step is probably the slowest (making the isolation of intermediates difficult). Note that as with hydrolyses of the halogens, the reaction is reversible—that is, that acidification of a solution containing sulfide and sulfite (or selenide and selenite) yields the elementary chalcogen. 

Reaction of the -hydroxy selenides with phosphorus triiodide or A. A -carbonyl-diimidazole leads to elimination of both the hydroxy and selanyl moieties, and, as with the / -hydroxy silanes, to formation of alkylidenecyclopropanes (see Section 5.2.2.7.3.). 

Interdependence of phosphorus-selenium couplings in bicyclic phosphorus selenide compounds has been studied by Tattershall and Sandham. " The knowledge of the rules which govern this parameter facilitates considerably an analysis of the spectra of new compounds, in particular symmetrical ones. 

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