1,1-Bis(diphenylphosphino)methane (dppm), is an organophosphorus compound with the formula CH<sub>2</sub>(PPh<sub>2</sub>)<sub>2</sub>. Dppm, a white, crystalline powder, is used in inorganic and organometallic chemistry as a ligand. It is more specifically a chelating ligand because it is a ligand that can bond to metals with two phosphorus donor atoms. The natural bite angle is 73ð.
1,1-Bis(diphenylphosphino)methane was first prepared by the reaction of sodium diphenylphosphide (Ph<sub>2</sub>PNa) with dichloromethane:
The methylene group (CH<sub>2</sub>) in dppm (and especially its complexes) is mildly acidic. The ligand can be oxidized to give the corresponding oxides and sulfides CH<sub>2</sub>[P(E)Ph<sub>2</sub>]<sub>2</sub> (E = O, S). The methylene group is even more acidic in these derivatives.
As a chelating ligand, 1,1-bis(diphenylphosphino)methane forms a four-membered ring with the constituents MP<sub>2</sub>C. The ligand promotes the formation of bimetallic complexes that feature five-membered M<sub>2</sub>P<sub>2</sub>C rings. In this way, dppm promotes the formation of bimetallic complexes. One such example is the dipalladium chloride, Pd<sub>2</sub>Cl<sub>2</sub>(dppm)<sub>2</sub>. 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.