Bis(diphenylphosphino)methane

Synthesis and reactivity

1,1-Bis(diphenylphosphino)methane was first prepared by the reaction of sodium diphenylphosphide (Ph2PNa) with dichloromethane: :Ph3P + 2 Na → Ph2PNa + NaPh :2NaPPh2 + CH2Cl2 → Ph2PCH2PPh2 + 2 NaCl

The methylene group (CH2) in dppm (and especially its complexes) is mildly acidic. The ligand can be oxidized to give the corresponding oxides and sulfides CH2[P(E)Ph2]2 (E = O, S). The methylene group is even more acidic in these derivatives.

Coordination chemistry

As a chelating ligand, 1,1-bis(diphenylphosphino)methane forms a four-membered ring with the constituents MP2C. The ligand promotes the formation of bimetallic complexes that feature five-membered M2P2C rings. In this way, dppm promotes the formation of bimetallic complexes. One such example is the dipalladium chloride, Pd2Cl2(dppm)2. In this complex, the oxidation state for the Pd centres are I. Bis(diphenylphosphino)methane gives rise to a family of coordination compounds known as A-frame complexes.

References

References

1. (1993). "Mixed-Metal Cluster Chemistry". [[Organometallics]].
2. (2009). "Bite angle effects of diphosphines in C–C and C–X bond forming cross coupling reactions". Chemical Society Reviews.
3. W. Hewertson. (1962). "The preparation of di- and tri-tertiary phosphines". [[J. Chem. Soc.]].
4. {{cite encyclopedia. (2006). Albéniz, Ana C.
5. G. Besenyei. (January 2002). "Crystallographic characterization of the palladium(I) dimers, ''syn''-Pd₂Cl₂(dppmMe)₂ and Pd₂Cl₂(dppm)₂; solution conformational behavior of ''syn''- and ''anti''-Pd₂Cl₂(dppmMe)₂ and their (μ-Se) adducts [dppmMe=μ-1,1-bis(diphenylphosphino)ethane, and DPPM=μ-bis(diphenylphosphino)methane]". Inorg. Chim. Acta.