Bis(diphenylphosphino)methane

1,1-Bis(diphenylphosphino)methane (dppm), is an organophosphorus compound with the formula CH₂(PPh₂)₂. Dppm, a white, crystalline powder, is used in inorganic and organometallic chemistry as a ligand.^[1] 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 73°.^[2]

1,1-bis(diphenylphosphino)­methane

Names
Preferred IUPAC name Methylenebis(diphenylphosphane)
Other names Methylenebis(diphenylphosphine) dppm
Identifiers
CAS Number	2071-20-7 Y
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL307780 Y
ChemSpider	67509 Y
ECHA InfoCard	100.016.541
EC Number	218-194-2
PubChem CID	74952
UNII	I5O2HZR38V Y
CompTox Dashboard (EPA)	DTXSID10174766
InChI InChI=1S/C25H22P2/c1-5-13-22(14-6-1)26(23-15-7-2-8-16-23)21-27(24-17-9-3-10-18-24)25-19-11-4-12-20-25/h1-20H,21H2 Y Key: XGCDBGRZEKYHNV-UHFFFAOYSA-N Y InChI=1/C25H22P2/c1-5-13-22(14-6-1)26(23-15-7-2-8-16-23)21-27(24-17-9-3-10-18-24)25-19-11-4-12-20-25/h1-20H,21H2 Key: XGCDBGRZEKYHNV-UHFFFAOYAH
SMILES P(c1ccccc1)(c2ccccc2)CP(c3ccccc3)c4ccccc4
Properties
Chemical formula	C25H22P2
Molar mass	384.399 g·mol−1
Appearance	White crystalline powder
Melting point	118 to 122 °C (244 to 252 °F; 391 to 395 K)
Solubility in water	Insoluble in water
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319, H335
Precautionary statements	P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501
Safety data sheet (SDS)	External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Synthesis and reactivity

1,1-Bis(diphenylphosphino)methane was first prepared by the reaction of sodium diphenylphosphide (Ph₂PNa) with dichloromethane:^[3]

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.^[4]

Ball-and-stick model of [Pd₂Cl₂(dppm)₂].^[5]