Chapter 3 - Organobismuth(V) Compounds

Abstract

Oxidation of triarylbismuthines to pentavalent triarylbismuth dihalides is accomplished using a variety of halogenating agents such as molecular halogens, sulfur dichloride, disulfur dichloride, thionyl chloride, sulfuryl chloride, phenyliodine dichloride, xenon difluoride, iodine pentafluoride, and iodine trichloride. Lead tetraacetate, benzoyl peroxide, and benzoyl nitrate can convert triarylbismuthines to the corresponding triarylbismuth(V) dicarboxylates or dinitrates. Metathetical reaction of triarylbismuth dihalides and their derivatives is widely used for the preparation of triarylbismuth(V) compounds of the type Ar3BiX2, where X denotes an anionic group. Triphenylbismuthine is oxidized by N-bromosuccinimide, lead tetraacetate, or benzoyl nitrate to give triphenylbismuth bromo(succinimide), diacetate, and dinitrate, respectively. Triphenylbismuthine reacts irreversibly with sulfur dioxide within 5 minutes to give crystalline precipitates of composition Ph3BiS2O4. Most triarylbismuth(V) compounds of the type Ar3BiX2 are crystalline, nonhygroscopic solids, which are soluble in benzene, chloroform, dichloromethane, dioxane, THF, and acetone; slightly soluble in alcohols and diethyl ether; and insoluble in hexane. Tris(hydroxyphenyl)bismuth dichlorides are soluble in methanol, but hardly soluble in water. Triphenylbismuth carbonate is insoluble in most organic solvents, suggesting that the polymeric structure of the Ph3Bi units is linked by the carbonate anions. The thermal stability of these compounds is highly dependent on the nature of the anionic groups attached.