1,2-Bis(diphenylphosphino)ethane

1,2-Bis(diphenylphosphino)ethane (dppe) is an organophosphorus compound with the formula (Ph₂PCH₂)₂ (Ph = phenyl). It is a common symmetrical bidentate ligand in coordination chemistry. It is a white solid that is soluble in organic solvents.

1,2-Bis(diphenylphosphino)ethane

dppe
Names
Preferred IUPAC name (Ethane-1,2-diyl)bis(diphenylphosphane)
Other names 1,2-Bis(diphenylphosphino)ethane Diphos Dppe
Identifiers
CAS Number	1663-45-2 Y
3D model (JSmol)	Interactive image Interactive image
Beilstein Reference	761261
ChEBI	CHEBI:30669 Y
ChEMBL	ChEMBL68683 Y
ChemSpider	66873 Y
ECHA InfoCard	100.015.246
EC Number	216-769-2
Gmelin Reference	9052
PubChem CID	74267
UNII	KL33QE52I4
CompTox Dashboard (EPA)	DTXSID2061858
InChI InChI=1S/C26H24P2/c1-5-13-23(14-6-1)27(24-15-7-2-8-16-24)21-22-28(25-17-9-3-10-18-25)26-19-11-4-12-20-26/h1-20H,21-22H2 Y Key: QFMZQPDHXULLKC-UHFFFAOYSA-N Y InChI=1/C26H24P2/c1-5-13-23(14-6-1)27(24-15-7-2-8-16-24)21-22-28(25-17-9-3-10-18-25)26-19-11-4-12-20-26/h1-20H,21-22H2 Key: QFMZQPDHXULLKC-UHFFFAOYAX
SMILES P(c1ccccc1)(c2ccccc2)CCP(c3ccccc3)c4ccccc4 c1ccc(cc1)P(CCP(c2ccccc2)c3ccccc3)c4ccccc4
Properties
Chemical formula	C26H24P2
Molar mass	398.42 g/mol
Melting point	140 to 142 °C (284 to 288 °F; 413 to 415 K)
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H302, H315, H319, H332, H335, H410
Precautionary statements	P261, P264, P270, P271, P273, P280, P301+P312, P302+P352, P304+P312, P304+P340, P305+P351+P338, P312, P321, P330, P332+P313, P337+P313, P362, P391, P403+P233, P405, P501
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

Preparation

The preparation of dppe entails the alkylation of NaP(C₆H₅)₂ with 1,2-dichloroethane:^[1][2]

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

Reactions

The reduction of dppe by lithium give the disecondary phosphine:^[3]

(C₆H₅)₂PCH₂CH₂P(C₆H₅)₂ 4 Li → Li(C₆H₅)PCH₂CH₂P(C₆H₅)Li + 2 C₆H₅Li

Hydrolysis gives the bis(secondary phosphine).

Li(C₆H₅)PCH₂CH₂P(C₆H₅)Li + 2 H₂O → H(C₆H₅)PCH₂CH₂P(C₆H₅)H + 2 LiOH

The bis(dppe) complex HFeCl(dppe)₂ is one of the most accessible transition metal hydrides.

Treatment of dppe with hydrogen peroxide produces the phosphine oxides (C₆H₅)₂P(O)CH₂CH₂P(C₆H₅)₂ and (C₆H₅)₂P(O)CH₂CH₂P(O)(C₆H₅)₂.^[4] Selective mono-oxidation of dppe can be achieved by benzylation followed by hydrolysis:

(C₆H₅)₂PCH₂CH₂P(C₆H₅)₂ + C₆H₅CH₂Br → (C₆H₅)₂PCH₂CH₂P(C₆H₅)₂(CH₂C₆H₅)]Br

(C₆H₅)₂PCH₂CH₂P(C₆H₅)₂(CH₂C₆H₅)]Br + NaOH → (C₆H₅)₂PCH₂CH₂P(O)(C₆H₅)₂ + C₆H₅CH₃ + NaBr

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

Coordination complexes

Many coordination complexes of dppe are known, and some are used as homogeneous catalysts. Dppe is almost invariably chelating, although there are examples of monodentate (e.g., W(CO)₅(dppe)) and of bridging behavior.^[5] The natural bite angle is 86°.^[6]

Related compounds

• 1,2-Bis(dimethylphosphino)ethane
• Bis(diphenylphosphino)methane

References

1. 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.
2. 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
3. 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. PMID 10814038.
4. Encyclopedia of Reagents for Organic Synthesis 2001 John Wiley & Sons, Ltd
5. 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
6. Birkholz (née Gensow), Mandy-Nicole; Freixa, Zoraida; van Leeuwen, Piet W. N. M. (2009). "Bite angle effects of diphosphines in C–C and C–X bond forming cross coupling reactions". Chemical Society Reviews. 38 (4): 1099–1118. doi:10.1039/B806211K. PMID 19421583.