1,2-Bis(diphenylphosphino)ethane

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1,2-Bis(diphenylphosphino)ethane
DPPE structure.svg
dppe
Names
IUPAC name
Ethane-1,2-diylbis(diphenylphosphane)
Other names
1,2-Bis(diphenylphosphino)ethane
Diphos
Dppe
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.015.246
Properties
C26H24P2
Molar mass 398.42 g/mol
Melting point 140 to 142 °C (284 to 288 °F; 413 to 415 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

1,2-Bis(diphenylphosphino)ethane (dppe) is a commonly used bidentate ligand in coordination chemistry. Dppe is almost invariably chelating, although there are examples of monodentate (e.g., W(CO)5(dppe)) and of bridging behavior.[1]

Preparation[edit]

The preparation of dppe is conducted via the alkylation of NaPPh2 which is typically prepared from triphenylphosphine (P(C6H5)3) as follows:[2][3]

P(C6H5)3 + 2 Na → NaP(C6H5)2 + NaC6H5

NaP(C6H5)2, which is readily air-oxidized, is treated with 1,2-dichloroethane (ClCH2CH2Cl) to give dppe:

2 NaP(C6H5)2 + ClCH2CH2Cl → (C6H5)2PCH2CH2P(C6H5)2 + 2 NaCl

Reactions[edit]

The reduction of dppe by lithium to give PhHP(CH2)2PHPh has been reported.[4]

Ph2P(CH2)2PPh2 + 4 Li → PhLiP(CH2)2PLiPh + 2 PhLi

Hydrolysis gives the bis(secondaryphosphine):

PhLiP(CH2)2PLiPh + 2 PhLi + 4H2O → PhHP(CH2)2PHPh + 4 LiOH + 2 C6H6
The bis(dppe) complex HFeCl(dppe)2 is one of the most accessible transition metal hydrides.

Treatment of dppe with conventional oxidants such as hydrogen peroxide (H2O2), aqueous bromine (Br2), etc., produces dppeO in low yield (e.g., 13%) as a result of non-selective oxidation.[5] Selective mono-oxidation of dppe can be achieved by reaction with PhCH2Br to give dppeO.

Ph2P(CH2)2PPh2 + PhCH2Br → Ph2P(CH2)2PPh2(CH2Ph)+Br

 

 

 

 

(2.3.)

Ph2P(CH2)2PPh2(CH2Ph)+Br + NaOH + H2O → Ph2P(CH2)2P(O)Ph2

 

 

 

 

(2.4.)

Hydrogenation of dppe gives the ligand bis(dicyclohexylphosphino)ethane.

Many coordination complexes of dppe are known, and some are used as homogeneous catalysts.

References[edit]

  1. ^ Cotton, F.A.; Wilkinson, G. Advanced Inorganic Chemistry: A Comprehensive Text, 4th ed.; Wiley-Interscience Publications: New York, NY, 1980; p.246. ISBN 0-471-02775-8
  2. ^ W. Hewertson and H. R. Watson (1962). "283. The preparation of di- and tri-tertiary phosphines". J. Chem. Soc.: 1490–1494. doi:10.1039/JR9620001490. 
  3. ^ Girolami, G.; Rauchfuss, T.; Angelici, R. Synthesis and Technique in Inorganic Chemistry, 3rd ed.; University Science Books: Sausalito, CA, 1999; pp. 85-92. ISBN 0-935702-48-2
  4. ^ Dogan, J.; Schulte, J.B.; Swiegers, G.F.; Wild, S.B. (2000). "Mechanism of Phosphorus-Carbon Bond Cleavage by Lithium in Tertiary Phosphines. An Optimized Synthesis of 1, 2-Bis (phenylphosphino) ethane". J. Org. Chem. 65 (4): 951–957. doi:10.1021/jo9907336. 
  5. ^ Encyclopedia of Reagents for Organic Synthesis 2001 John Wiley & Sons, Ltd