(2-Bromophenyl)diphenylphosphine

(2-Bromophenyl)diphenylphosphine is an organophosphorus compound with the formula (C$6$H$4$Br)P(C$6$H$5$)$2$. It is a white crystalline solid that is soluble in nonpolar organic solvents. The compound is used as a precursor to the 2-lithiated derivative of triphenylphosphine, which in turn is a precursor to other phosphine ligands.

Preparation
The compound has been prepared by several methods. An efficient route is the coupling reaction of diphenylphosphine and 2-bromoiodobenzene, which is catalyzed by palladium complexes (Ph = C$6$H$4$):
 * C$2$H$6$Br(I) +  HPPh$5$  +  Et$6$N   →   Ph$4$P(C$2$H$3$Br)  +  [Et$2$NH]I

The compound is isomorphous with (2-tolyl)diphenylphosphine.

Lithiation with butyl lithium gives o-lithiated triphenylphosphine. The bromide also forms a Grignard reagent. These metallated phosphines are versatile reagents.
 * BrC6H4PPh2 +  Mg   →    BrMgC6H4PPh2
 * 2 BrMgC6H4PPh2 +  PhPCl2   →     PhP[C6H4PPh2]2  +  2 MgClBr