1,3-Bis(diphenylphosphino)propane (dppp) is an organophosphorus compound with the formula PhP(CH)PPh. The compound is a white solid that is soluble in organic solvents. It is slightly air-sensitive, degrading in air to the phosphine oxide. It is classified as a diphosphine ligand in coordination chemistry and homogeneous catalysis.
The diphosphine can be prepared by the reaction of lithium diphenylphosphide and 1,3-dichloropropane (Ph = CH): 2 PhPLi + Cl(CH)Cl → PhP(CH)PPh + 2 LiCl
However, it can be synthesised via a much more controllable (and cheaper) route, via metal-halogen exchange and then metathesis: Br(CH)Br + 2 BuLi → Li(CH)Li + 2 BuBr Li(CH)Li + 2 PCl → ClP(CH)PCl + 2 LiCl ClP(CH)PCl + 4 PhLi → PhP(CH)PPh + 4 LiCl
Coordination chemistry and use as co-catalyst The diphosphine serves as a bidentate ligand forming six-membered CPM chelate ring with a natural bite angle of 91°. For example, the complex dichloro(1,3-bis(diphenylphosphino)propane)nickel is prepared by combining equimolar portions of the ligand and nickel(II) chloride hexahydrate. This nickel complex serves as a catalyst for the Kumada coupling reaction. Dppp is also used as a ligand for palladium(II) catalysts to co-polymerize carbon monoxide and ethylene to give polyketones. Dppp can sometimes be used in palladium-catalyzed arylation under Heck reaction conditions to control regioselectivity.Cabri, Walter; Candiani, Ilaria; Bedeschi Angelo; Penco, Sergio"α-Regioselectivity in Palladium-Catalyzed Arylation of Acyclic Enol Ethers" journal= Journal of Organic Chemistry, 1991, volume 57, p. 1481.
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