Cyclopentaphosphine

Cyclopentaphosphine
Names
	IUPAC name pentaphospholane
	Other names Cyclopentaphosphane, pentaphosphole
Identifiers
CAS Number	6798-45-4 ;
3D model (JSmol)	Interactive image;
ChemSpider	546991;
EC Number	235-633-3;
PubChem CID	629880;
CompTox Dashboard (EPA)	DTXSID50924646 ;
	InChI InChI=1S/H5P5/c1-2-4-5-3-1/h1-5H Key: MSVKYECZFNAJJY-UHFFFAOYSA-N;
	SMILES P1PPPP1;
Properties
Chemical formula	H5P5
Molar mass	159.909 g/mol
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Cyclopentaphosphine is the inorganic compound with the formula (PH)₅. It is prepared by the hydrolysis of cyclo-[PSiMe₃]₄ (Me = methyl). Although only of theoretical interest, (PH)₅ is parent of many related cyclic polyphosphines that are the subject of research.

Organic cyclophosphines

Structure of (2-pyridylP)₅.^[1] Color code: maroon = P, black = C, white = H, blue = N.

Organic cyclophosphanes are a family of organophosphorus compounds with the formula (RP)_n where R is an organic substituent. Many examples are known. They are white, air-sensitive solids which have good solubility in organic solvents. Well-characterized examples are known for ring sizes 3–6. The three-membered rings feature bulky substituents, e.g., [tert-BuP]₃.

The cyclophosphines can be prepared by several methods, one involves reductive coupling of dichlorophosphines:^[2]

5 PhPCl₂ + 5 Mg → [PhP]₅ + 5 MgCl₂

Isomerism

The structures are complicated by the slow pyramidal inversion at phosphorus(III). In principle, many isomers are possible for cyclo-P₅R₅, but usually only one is observed.^[3] All phenyl substituents are equatorial in cyclo-P₆(C₆H₅)₆.^[4]

References

^ Schoemaker, Robin; Schwedtmann, Kai; Franconetti, Antonio; Frontera, Antonio; Hennersdorf, Felix; Weigand, Jan J. (2019). "Controlled Scrambling Reactions to Polyphosphanes via Bond Metathesis Reactions". Chemical Science. 10 (48): 11054–11063. doi:10.1039/C9SC04501E. PMC 7066665. PMID 32190255.
^ Marianne Baudler, Klaus Glinka (1993). "Monocyclic and Polycyclic Phosphines". Chem. Rev. 93: 1623–1667. doi:10.1021/cr00020a010.
^ Hoffman, P. R.; Caulton, K. G. (1975). "Conformational Stability and Ring-Size Integrity of Cyclic Polyphosphines". Inorganic Chemistry. 14 (8): 1997–1999. doi:10.1021/ic50150a051.
^ Schmutzler, Reinhard; Heuer, Lutz; Schomburg, Dietmar (1993). "Transformations of Difluorophosphines: The Influence of Solvent on the Reaction Pathway and Ring Size in Cyclopolyphosphines". Phosphorus, Sulfur, and Silicon and the Related Elements. 83 (1–4): 149–156. doi:10.1080/10426509308034357.

[1] Schoemaker, Robin; Schwedtmann, Kai; Franconetti, Antonio; Frontera, Antonio; Hennersdorf, Felix; Weigand, Jan J. (2019). "Controlled Scrambling Reactions to Polyphosphanes via Bond Metathesis Reactions". Chemical Science. 10 (48): 11054–11063. doi:10.1039/C9SC04501E. PMC 7066665. PMID 32190255.

[2] Marianne Baudler, Klaus Glinka (1993). "Monocyclic and Polycyclic Phosphines". Chem. Rev. 93: 1623–1667. doi:10.1021/cr00020a010.

[3] Hoffman, P. R.; Caulton, K. G. (1975). "Conformational Stability and Ring-Size Integrity of Cyclic Polyphosphines". Inorganic Chemistry. 14 (8): 1997–1999. doi:10.1021/ic50150a051.

[4] Schmutzler, Reinhard; Heuer, Lutz; Schomburg, Dietmar (1993). "Transformations of Difluorophosphines: The Influence of Solvent on the Reaction Pathway and Ring Size in Cyclopolyphosphines". Phosphorus, Sulfur, and Silicon and the Related Elements. 83 (1–4): 149–156. doi:10.1080/10426509308034357.

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