1,1-Bis(diphenylphosphino)methane (dppm), is an
organophosphorus compound
Organophosphorus chemistry is the scientific study of the synthesis and properties of organophosphorus compounds, which are organic compounds containing phosphorus. They are used primarily in pest control as an alternative to chlorinated hydrocarbo ...
with the formula CH
2(PPh
2)
2. Dppm, a white, crystalline powder, is used in inorganic and organometallic chemistry as a ligand. It is more specifically a
chelating ligand
Chelation () is a type of bonding of ions and their molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a Denticity, polydentate (multiple bonded) ligand and a single central metal atom ...
because it is a ligand that can bond to metals with two phosphorus donor atoms. The natural
bite angle
In coordination chemistry, the bite angle is the angle on a central atom between two bonds to a bidentate ligand. This ligand–metal–ligand geometric parameter is used to classify chelation, chelating ligands, including those in organometallic ...
is 73°.
Synthesis and reactivity
1,1-Bis(diphenylphosphino)methane was first prepared by the reaction of
sodium diphenylphosphide (Ph
2PNa) with dichloromethane:
:Ph
3P + 2 Na → Ph
2PNa + NaPh
:2NaPPh
2 + CH
2Cl
2 → Ph
2PCH
2PPh
2 + 2 NaCl
The methylene group (CH
2) in dppm (and especially its complexes) is mildly acidic. The ligand can be oxidized to give the corresponding oxides and sulfides CH
2 (E)Ph2sub>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 MP
2C. The ligand promotes the formation of bimetallic complexes that feature five-membered M
2P
2C rings. In this way, dppm promotes the formation of bimetallic complexes. One such example is the dipalladium chloride, Pd
2Cl
2(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 complex
In organometallic chemistry, A-frame complexes are coordination compounds that contain two bridging ligand, bridging bidentate ligands and a single atom bridge. They have the formula , where ''bd'' is a bidentate ligand like 1,1-bis(diphenylphosp ...
es.
References
{{reflist
Diphosphines
Phenyl compounds