dppp (1,3-Bis(diphenylphosphino)propane) | CAS 6737-42-4 | ≥97%

Technical Specifications

Product Description & Scientific Applications

dppp (1,3-bis(diphenylphosphino)propane; trimethylenebis(diphenylphosphine); propane-1,3-diylbis(diphenylphosphane)) is a bidentate diphosphine ligand whose three-carbon propane backbone binds a metal through both phosphorus donors in a six-membered chelate ring, giving an intermediate natural bite angle of about 91° — the chelation angle preferred by the ligand backbone itself. This places dppp between the tighter five-membered chelate of dppe and the wider chelate of dppb. Because the bite angle set by the backbone influences the geometry at the metal, and that geometry in turn affects how readily key catalytic steps proceed, dppp occupies a distinct and well-studied position in the dppe–dppp–dppb series used throughout homogeneous catalysis and coordination chemistry.

Bidentate ligand for Ni- and Pd-catalysed cross-coupling

The nickel complex NiCl2(dppp) is a benchmark precatalyst for Kumada–Tamao–Corriu coupling of aryl and vinyl halides with Grignard reagents, and is also applied in Suzuki–Miyaura, Negishi and Miyaura borylation reactions. As a free ligand, dppp supports palladium-mediated Suzuki–Miyaura and Sonogashira chemistry. The bite angle of the diphosphine is a practical handle on coupling efficiency: in palladium catalysis, wider P–M–P angles can favour geometries that facilitate reductive elimination, one of the product-forming steps in cross-coupling. dppp's intermediate angle makes it a standard reference point when screening how diphosphine geometry affects a given coupling.

Catalyst-transfer polymerisation for conjugated polymers

Ni(dppp)Cl2 is a benchmark initiator for Kumada catalyst-transfer polycondensation, a chain-growth route to regioregular conjugated polymers such as poly(3-hexylthiophene). In KCTP, chain control depends on the nickel centre remaining associated with the growing polymer after reductive elimination and transferring intramolecularly to the next carbon–halide terminus rather than dissociating into solution; termination can occur through catalyst dissociation or disproportionation. Comparative mechanistic studies of Ni(dppe)Cl2 and Ni(dppp)Cl2 show that changing the diphosphine bite angle changes the turnover-limiting step, with dppp-associated systems limited by transmetalation and dppe-associated systems limited by reductive elimination. This makes Ni(dppp)Cl2 a well-established precatalyst and mechanistic benchmark in conjugated-polymer synthesis.

Palladium-catalysed carbonylation

dppp is a well-established ligand for palladium-catalysed carbonylation, where carbon monoxide is incorporated into organic products or alternating copolymers. In selected Pd carbonylation systems, changing from an ethylene-bridged to a propylene-bridged diphosphine can change the product pathway, showing how backbone length and bite angle influence carbonylative reactivity. A major example is carbon monoxide–ethylene copolymerisation to alternating polyketones, where a cis-chelating Pd/dppp environment supports repeated CO/alkene insertion. The same ligand supports carbonylative synthesis of chromenone and coumarin scaffolds from salicylic aldehydes and benzyl chlorides, and dearomative carbonylation of indole substrates.

Coordination chemistry and model complexes

dppp forms well-defined chelate complexes with nickel, palladium and platinum, including square-planar M(dppp)X2 species and related bis(diphosphine) complexes. Spanning a single metal through a six-membered ring, dppp favours cis coordination of its two donors, and because its bite angle sits between dppe and dppb, these complexes are standard reference points for relating diphosphine geometry to metal-complex structure.

Handling note

As a tertiary arylphosphine, dppp is mildly air-sensitive and oxidises slowly to the phosphine oxide; minimise air exposure and handle under inert atmosphere where ligand purity is critical.

Further reading: Practical guidance on choosing a phosphine ligand for palladium- and nickel-catalysed cross-coupling in NorrChemica's Lab Journal: Phosphine Ligands for Cross-Coupling.

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