1,2-Bis(diphenylphosphino)ethane

1,2-Bis(diphenylphosphino)ethane
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 ;
3D model (JSmol)	Interactive image; Interactive image;
Beilstein Reference	761261
ChEBI	CHEBI:30669 ;
ChEMBL	ChEMBL68683 ;
ChemSpider	66873 ;
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 Key: QFMZQPDHXULLKC-UHFFFAOYSA-N ; 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). verify (what is ?) Infobox references

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

Preparation

The preparation of dppe is by the alkylation of NaPPh₂:[1][2]

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

The reduction of dppe by lithium to give PhHP(CH₂)₂PHPh has been reported.[3]

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

Hydrolysis gives the bis(secondary phosphine):

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.[4] 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.

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

References

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.
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
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.
Encyclopedia of Reagents for Organic Synthesis 2001 John Wiley & Sons, Ltd
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
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.

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[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.

[Encycl1-4] Encyclopedia of Reagents for Organic Synthesis 2001 John Wiley & Sons, Ltd

[Cotton1-5] 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

[vanLeeuwen-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.