Tertiary phosphine selenides

Tertiary phosphine selenides, RjPSe, can be prepared by direct addition of selenium to the appropriate phosphine, using an inert solvent. Aromatic tertiary phosphine selenides can be prepared by reaction (9.653) which appears to be specific for seleninm derivatives. 

Exchange can be used to obtain selenides (9.654) if R jP is more basic than R3P [14]. 

The formal P=Se linkage is believed to have less it character than P=S, but several addition complexes are known, for example, Eqnation 9.655 (Table 9.8). 

3 Orcanohalides AND Esters Selenohalides can be obtained by direct addition. 

Direct addition can be used to obtain other derivatives (9.660) and (9.661), while halides can be obtained from these with sulphuryl chloride (9.662). 

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Tertiary phosphine selenides have been prepared either by direct fusion of the tertiary phosphine with elemental selenium1 or by refluxing the phosphine with selenium in an inert solvent.2 In the case of a solid phosphine, such preparations often require numerous and time-consuming extractions to obtain the pure phosphine selenide. 

Tertiary phosphine sulfides are generally stable compounds and are not easily oxidised by air, although they can be oxidised by hydrogen peroxide or dilute nitric acid. The analogous tertiary phosphine selenides and tellurides are however, more reactive to oxidation. Similar to the sulfides they can be prepared from the direct reaction of elemental chalcogen with a tertiary phosphine (Equation 1). Tertiary phosphine selenides are also accessible from tertiary phosphines using KSeCN as the selenium source instead of the element itself. 

In particular, the reaction of tertiary phosphine selenides with metal carbonyl complexes " provided a simple, one-step synthetic procedure for the formation of selenido clusters through oxidative transfer of selenium atoms to low-valent metal centers, taking advantage of the reactivity of the P=Se bond. 

L. Maier, Tertiary phosphine selenides-, in G.M. Kosolapoff and L. Maier, Eds., Organic Phosphorus... 

Includes bibliographical references and indexes. Contents v. 1. Primary, secondary, and tertiary phosphines, polyphosphines, and heterocyclic organo-phosphorus(III) compounds—v. 2. Phosphine oxides, sulphides, selenides, and tellurides—v. 3. Phosphonium salts, ylides, and phosphoranes. 

All the tertiary phosphines are highly refractive liquids, lighter than and insoluble in water. Those of low molecular weight readily absorb oxygen from the air, yielding oxides they also have indescribably unpleasant odours. The compounds combine with sulphur, selenium and carbon disulphide, forming respectively sulphides, selenides and compounds of the type... 

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