lithium diphenylphosphide
{{Chembox
|ImageFile = LiPPh2.png
|ImageSize = 120
|PIN = Lithium diphenylphosphanide
|Section1={{Chembox Identifiers
|CASNo = 4541-02-0
|PubChem = 3478053
|ChemSpiderID = 2719164
|DTXSID = DTXSID80392839
|StdInChI=1S/C12H10P.Li/c1-3-7-11(8-4-1)13-12-9-5-2-6-10-12;/h1-10H;/q-1;+1
|StdInChIKey = WKUYEGHEUWHKIU-UHFFFAOYSA-N
|SMILES = [Li+].C1=CC=C(C=C1)[P-]C2=CC=CC=C2
}}
|Section2={{Chembox Properties
|C=12|H=10|Li=1|P=1
|Appearance = pale yellow solid
|Solubility = Reacts with water
|SolubleOther = Ethers, hydrocarbons}}
|Section3={{Chembox Hazards
|GHSPictograms = {{GHS05}}{{GHS07}}{{GHS09}}
|GHSSignalWord = Danger
|HPhrases = {{H-phrases|302|312|314|332|410}}
|PPhrases = {{P-phrases|260|261|264|270|271|273|280|301+312|301+330+331|302+352|303+361+353|304+312|304+340|305+351+338|310|312|321|322|330|363|391|405|501}}
}}
}}
Lithium diphenylphosphide contains lithium and the organophosphorus anion with the formula {{chem2|(C6H5)2PLi}}. It is a red, air-sensitive solid that is used in the preparation of diphenylphosphino compounds.
Synthesis and reactions
The lithium, sodium, and potassium salts are prepared by reduction of chlorodiphenylphosphine,{{Cite encyclopedia |title=Inorganic Syntheses |date=1972 |editor-last=Cotton |editor-first=F. A. |volume=13 |pages=26–32 |doi=10.1002/9780470132449.ch7 |isbn=9780470132449 |last2=Cohn |first2=Kim |last3=Hawthorne |first3=M. F. |last4=Dunks |first4=G. B. |last5=Wilson |first5=R. J. |chapter=Diphenyl(trimethylsilyl)phosphine and Dimethyl(trimethylsilyl)‐phosphine |first1=R. |last1=Goldsberry}} triphenylphosphine,{{Cite encyclopedia |title=Inorganic Syntheses |date=1977 |editor-last=MacDiarmid |editor-first=Alan G. |volume=17 |pages=186–188 |doi=10.1002/9780470132487.ch51 |isbn=9780470132487 |last2=Beyerle |first2=Gordon |last3=Cox |first3=Daniel |last4=Cohn |first4=Kim |chapter=Lithium Diphenylphosphide and Diphenyl(Trimethylsilyl)Phosphine |first1=George W. III |last1=Luther}}{{Cite encyclopedia |title=Inorganic Syntheses |date=1976 |editor-last=Basolo |editor-first=Fred |volume=16 |pages=161–188 |doi=10.1002/9780470132470.ch43 |isbn=9780470132470 |last2=Doronzo |first2=S. |last3=Chan |first3=J. |last4=Bennett |first4=M. A. |chapter=Diphenylphosphine |first1=V. D. |last1=Bianco}} or tetraphenyldiphosphine with alkali metals (M):
: {{chem2|(C6H5)2PCl + 2 M → (C6H5)2PM + MCl}}
: {{chem2|(C6H5)3P + 2 M → (C6H5)2PM + MC6H5}}
: {{chem2|(C6H5)4P2 + 2 M → 2 (C6H5)2PM}}
They can also be obtained by deprotonation of diphenylphosphine.
With water, the salts convert to diphenylphosphine:
: {{chem2|(C6H5)2PLi + H2O → (C6H5)2PH + LiOH}}
With halocarbons, the salts react to give tertiary phosphines:{{Cite encyclopedia |title=Inorganic Syntheses |date=1976 |editor-last=Basolo |editor-first=Fred |volume=16 |pages=188–192 |doi=10.1002/9780470132470.ch50 |isbn=9780470132470 |last2=Mcauliffe |first2=C. A. |last3=Barth |first3=R. C. |last4=Grim |first4=S. O. |chapter=Cis‐2‐Diphenylarsinovinyldiphenylphosphine and 2‐Diphenylarsinoethyldiphenylphosphine |first1=W. |last1=Levason}}
: {{chem2|(C6H5)2PM + RX → (C6H5)2PR + MX}}
When treated with metal halides, lithium diphenylphosphide gives transition metal phosphido complexes.
Structure and physical properties
Although treated as salts, alkali diphenylphosphides are highly aggregated in solution. They adopt polymeric structures as solids.
{{Gallery |mode=packed |align=center |height=300
|File:DOXDUP.png|Part of the polymeric structure of {{chem2|LiPPh2(Et2O)}}.{{Cite journal |last1=Bartlett |first1=Ruth A. |last2=Olmstead |first2=Marilyn M. |last3=Power |first3=Philip P. |author-link3=Philip P. Power |date=1986 |title=Structural Characterization of the Solvate Complexes of the Lithium Diorganophosphides [{Li(Et2O)PPh2}∞], [{Li(THF)2PPh2}∞], and [{Li(THF)P(C6H11)2}∞] |journal=Inorg. Chem. |volume=25 |pages=1243–1247 |doi=10.1021/ic00228a034}}
}}
As an ether complex, the lithium salt is dark red.{{cite blog|url=https://labphoto.tumblr.com/post/90581200077/the-reaction-of-triphenylphosphine-with-lithium|title=The reaction of triphenylphosphine with lithium....|date=12 Dec 2012|first=Kristof|last=Hegedüs|publisher=Tumblr|access-date=6 January 2025|archive-url=http://web.archive.org/web/20201112030941/https://labphoto.tumblr.com/post/90581200077/the-reaction-of-triphenylphosphine-with-lithium|archive-date=12 November 2020|website=Pictures from an Organic Chemistry Laboratory|url-status=live}}
Related compounds
- Sodium diphenylphosphide (CAS RN 4376-01-6)
- Potassium diphenylphosphide (CAS RN 15475-27-1)