dppm (Bis(diphenylphosphino)methane) | CAS 2071-20-7 | 98%

dppm (1,1-bis(diphenylphosphino)methane; methylenebis(diphenylphosphine)) is a classical diphosphine ligand in which a single methylene unit links the two phosphorus donor atoms. This short backbone gives dppm a small natural bite angle of about 73°, so chelation to a single metal forms a strained four-membered ring. Its defining behaviour, however, is bridging two metal centres and holding them in close proximity, making dppm a classic ligand for binuclear and cluster chemistry. The methylene group between the two phosphorus atoms is mildly acidic, especially in coordinated complexes, and can be deprotonated or further functionalised.

Bridging ligand for bimetallic and A-frame complexes

dppm is one of the defining short-bridge diphosphines for assembling binuclear complexes in which two metal centres are held face-to-face by one or more μ-dppm ligands. It is closely associated with A-frame complexes, where a pair of square-planar metal centres is spanned by two bridging dppm ligands and a single bridging atom or group such as carbonyl, hydride, chloride, or a related small bridging ligand. Such systems are documented for metals that favour square-planar geometry, including rhodium, iridium, nickel, palladium, platinum, and gold, and are used to study metal–metal cooperativity, bridging-ligand chemistry, and two-centre reactivity.

Cluster synthesis and di- and polynuclear coordination chemistry

As a short-bite ligand, dppm is used to prepare di- and polynuclear coordination compounds and metal clusters, including palladium, platinum, silver, and gold assemblies. The rigid single-carbon bridge enforces close metal–metal contact, supporting the study of bimetallic cooperativity and two-centre reactivity. It is also used as a supporting ligand in homogeneous catalysis where small bite angle or bimetallic proximity is relevant.

Coinage-metal assemblies and Au(I) luminescence

dppm is used to construct polynuclear coinage-metal assemblies, with Au(I) systems especially prominent in studies of aurophilic interactions and luminescence. Binuclear and polynuclear gold(I) complexes bridged by dppm can hold gold centres at close range, giving rise to Au···Au interactions and associated emission behaviour. These systems are studied for structure–emission relationships, aurophilic interactions, and supramolecular solid-state behaviour.

Reference small-bite-angle diphosphine

Because of its well-defined short backbone, dppm is often used as a small-bite-angle comparator when probing the influence of bite angle on the structure, stability, and reactivity of metal complexes. It can act either as a strained chelate at a single metal or as a bridge between two metals, allowing the same ligand to serve in both roles across comparative studies.

Handling note

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