Bismuthines tertiary

A number of tertiary bismuthines have been prepared by the iateraction of a sodium diaryl- or dialkylbismuthide and an alkyl or aryl haUde (50) ... 

This method is of particular value for the preparation of unsymmetrical tertiary bismuthines. 

There have been several reports of the formation of tertiary bismuthines by the action of free radicals on metallic bismuth. One method of generating the radicals iavolves cleavage of ethane or hexafluoroethane ia a radiofrequeacy glow discharge apparatus the radicals thus formed are allowed to oxidize the metal at — 196°C (53). Trimethylbismuthiae and tris(trifluoromethyl)bismuthine [5863-80-9], C BiF, have been obtained by this procedure. 

Other methods of preparing tertiary bismuthines have been used only to a limited extent. These methods iaclude the electrolysis of organometaUic compounds at a sacrificial bismuth anode (54), the reaction between a sodium—bismuth or potassium—bismuth alloy and an alkyl or aryl haUde (55), the thermal elimination of sulfur dioxide from tris(arenesulfiaato)bismuthines (56), and the iateraction of ketene and a ttis(dialkylainino)bismuthine (57). 

All three carboa—bismuth boads of trihen zylhismuthine [99715-52-3], C2 H2 Bi, (64) and triphenylbismuthine (65) can be cleaved by alkafl metals. Under some conditions, however, tertiary bismuthines react with sodium or potassium to yield secondary bismuthides. Thus a number of sodium dialkylbismuthides have been obtained by the iateraction of a trialkylbismuthine and sodium ia Hquid ammonia (66—69) ... 

The secondary bismuthides discussed herein are useful for preparing several types of organobismuth compounds, eg, tertiary bismuthines and dibismuthines. 

Although trialkyl- and triarylbismuthines are much weaker donors than the corresponding phosphoms, arsenic, and antimony compounds, they have nevertheless been employed to a considerable extent as ligands in transition metal complexes. The metals coordinated to the bismuth in these complexes include chromium (72—77), cobalt (78,79), iridium (80), iron (77,81,82), manganese (83,84), molybdenum (72,75—77,85—89), nickel (75,79,90,91), niobium (92), rhodium (93,94), silver (95—97), tungsten (72,75—77,87,89), uranium (98), and vanadium (99). The coordination compounds formed from tertiary bismuthines are less stable than those formed from tertiary phosphines, arsines, or stibines. 

Tertiary bismuthines appear to have a number of uses in synthetic organic chemistry (32), eg, they promote the formation of 1,1,2-trisubstituted cyclopropanes by the iateraction of electron-deficient olefins and dialkyl dibromomalonates (100). They have also been employed for the preparation of thin films (qv) of superconducting bismuth strontium calcium copper oxide (101), as cocatalysts for the polymerization of alkynes (102), as inhibitors of the flammabihty of epoxy resins (103), and for a number of other industrial purposes. 

Halobismuthines, Dihalobismuthines, and Related Compounds. Chloro-, dichloro-, bromo-, and dibromobismuthines are best prepared by the reaction of a tertiary bismuthine and bismuth trichloride or tribromide (7,43,45,46,104—107) ... 

There is a report154 of Ph2Bi being formed from Ph2BiI and Na/liq. NH3, but instability complicates synthetic utility. Very little is known about tertiary bismuthines, although Ph3Bi is available. 

Due to the low nucleophilicity of the lone pair, tertiary bismuthines have found little use in the construction of onium salts and transition metal complexes. Trimethylbismuthine reacts with methyl triflate in acetonitrile to yield tetramethylbismuthonium triflate, which has so far been the only known example of tetraalkylbismuthonium salts [94AG(E)976]. Some transition metal complexes coordinated by tertiary bismuthine have been reported. They are described in Section 2.4. 

The second class of compounds, namely RgBiX, although represented by solid products, is a decidedly unstable class. The compounds are prepared by the halogenation of the tertiary bismuthines ... 

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