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.
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| Names | |
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| Preferred IUPAC name
(Ethane-1,2-diyl)bis(diphenylphosphane) | |
| Other names
1,2-Bis(diphenylphosphino)ethane
Diphos Dppe | |
| Identifiers | |
3D model (JSmol)
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| 761261 | |
| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| ECHA InfoCard | 100.015.246 |
| EC Number |
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| 9052 | |
PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| C26H24P2 | |
| Molar mass | 398.42 g/mol |
| Melting point | 140 to 142 °C (284 to 288 °F; 413 to 415 K) |
| Hazards | |
| GHS labelling: | |
 
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| Warning | |
| H302, H315, H319, H332, H335, H410 | |
| 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).
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Preparation edit
The preparation of dppe entails the alkylation of NaPPh2 with 1,2-dichloroethane:[1][2]
- 2 NaP(C6H5)2 + ClCH2CH2Cl → (C6H5)2PCH2CH2P(C6H5)2 + 2 NaCl
Reactions edit
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 pproduces 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 edit
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 edit
References edit
- ^ 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.