Pentaphenylbismuth is an organobismuth compound with formula , often abbreviated as , where Ph stands for phenyl. It is a violet crystalline solid. A molecule of pentaphenylbismuth consists of five phenyl groups attached to one bismuth atom. In this compound, bismuth is hypervalent.
Pentaphenylbismuth was prepared by Georg Wittig et al. and his coworker K. Clauss in 1952.
Pentaphenylbismuth can be synthesized by reaction of triphenylbismuth dichloride with phenyllithium.
Triphenylbismuth dichloride itself can be synthesized by oxidation of triphenylbismuth by sulfuryl chloride.
A strong violet color and strong dichroism of pentaphenylbismuth are very unusual for a compound of a main-group element. Bismith's lighter congeners, like antimony, never displays such behavior, nor when the bismuth's symmetry is D<sub>3h</sub>. The X-ray structure analysis done at shows that has a square pyramidal molecular geometry and is thus very similar to the colorless , which also has the same molecular geometry.
Pentaphenylbismuth is a useful reagent for the ortho-phenylation of phenols under mild conditions.
Pentaphenylbismuth reacts with sulfur dioxide to give diphenylsulfone under mild conditions in high yield.
Pentaphenylbismuth easily forms a bismuthonium cation, for example by reaction with p-toluenesulfonic acid:
Pentaphenylbismuth forms an ate complex upon reaction with phenyl lithium: