1,1-Bis(diphenylphosphino)methane

1,1-bis(diphenylphosphino)methane
IUPAC name methylenebis(diphenylphosphane)
Other names Methylenebis(diphenylphosphine) dppm
Identifiers
CAS number	2071-20-7 Y
ChemSpider	67509 Y
ChEMBL	CHEMBL307780 Y
Jmol-3D images	Image 1
SMILES P(c1ccccc1)(c2ccccc2)CP(c3ccccc3)c4ccccc4
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
Properties
Molecular formula	C25H22P2
Molar mass	384.39 g/mol
Appearance	White powder or crystalline powder
Melting point	118-122 °C
Solubility in water	Insoluble in water
Hazards
MSDS	External MSDS
R-phrases	36/37/38
S-phrases	22-24/25
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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 is attached to the central metals (the phosphorus) by bonds from two or more donor atoms.

Synthesis and reactivity

1,1-Bis(diphenylphosphino)methane was first prepared by the reaction of sodium diphenylphosphide (Ph₂PNa) with dichloromethane:^[2]

Ph₃P + 2 Na → Ph₂PNa + NaPh

2NaPPh₂ + CH₂Cl₂ → Ph₂PCH₂PPh₂ + 2 NaCl

The methylene group (CH₂) in dppm (and especially its complexes) are 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.^[3]

Ball-and-stick model of [Pd₂Cl₂(dppm)₂].^[4]

References

1. ^ Humphrey, Mark G.; Lee, Jeanne; Hockless, David C.R.; Skelton, Brian W.; & White, Allan H. (1993). "Mixed-Metal Cluster Chemistry". Organometallics 12 (3468): 3468. doi:10.1021/om00033a017. 
2. ^ W. Hewertson and H. R. Watson (1962). "The preparation of di- and tri-tertiary phosphines". J. Chem. Soc. 12: 1490–1494. doi:10.1039/JR9620001490. 
3. ^ Albéniz, Ana C. and Espinet, Pablo (2006). "Encyclopedia of Inorganic Chemistry". Encyclopedia of Inorganic Chemistry. doi:10.1002/0470862106.ia178. ISBN 0470860782. 
4. ^ G. Besenyei, L. Párkányia, E. Gács-Baitza, B. R. James (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 327 (1): 179–187. doi:10.1016/S0020-1693(01)00682-X.