Pentaphenylantimony

Chemical compound From Wikipedia, the free encyclopedia

Pentaphenylantimony is an organoantimony compound containing five phenyl groups attached to one antimony atom. It has formula Sb(C6H5)5 (or SbPh5).

Quick facts Names, Identifiers ...
Pentaphenylantimony
Names
Preferred IUPAC name
Pentaphenyl-λ5-stibane
Identifiers
3D model (JSmol)
ChemSpider
  • InChI=1S/5C6H5.Sb/c5*1-2-4-6-5-3-1;/h5*1-5H;
    Key: XJQGITRIKZCKRF-UHFFFAOYSA-N
  • C1=CC=C(C=C1)[Sb](C2=CC=CC=C2)(C3=CC=CC=C3)(C4=CC=CC=C4)C5=CC=CC=C5
Properties
C30H25Sb
Molar mass 507.290 g·mol−1
Appearance Colorless crystals[1]
Related compounds
Other cations
 PPh5
AsPh5
BiPh5
Related compounds
 Pentamethylantimony
Pentaethylantimony
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Structure

The structure of pentaphenylantimony has been the subject of several studies, and a definite ground state remains uncertain. The molecule adopts a roughly square pyramidal shape in the unsolvated crystal. In crystals of the solvate with cyclohexane or tetrahydrofuran, the compound adopts a trigonal bipyramidal shape.[2] When dissolved, molecules are also trigonal bipyramidal.[2] According to solution NMR measurements, the phenyl groups all appear to be equivalent, indicating fluxionality.[3]

Solid pure pentaphenylantimony forms triclinic crystals in the P1 space group. The unit cell has a=10.286 b=10.600 and c=13.594 Å, α=79.20° β=70.43° γ=119.52°. The basal Sb-C bond length is 2.216 Å whereas the apex Sb-C length is 2.115 Å.[1]

Reactions

Pentaphenylantimony reacts with a variety of protic reagents (hydrogen halides, carboxylic acids, methanol, etc). Benzene is one product as well as a tetraphenylantimony(V) compound:[4]

Ph5Sb + HOR → PhH + Ph4SbOR
Ph5Sb + HX → PhH + Ph4SbX

Halogens also cleave one Sb-phenyl bond:

Ph5Sb + X2 → Ph4SbX + PhX

When heated, pentaphenylantimony forms triphenylstibine, biphenyl and p-quaterphenyl.[5]

A reaction with carbon tetrachloride yields tetraphenylstibonium chloride, chlorobenzene, and benzene. Some of these reactions may proceed by radical pathways.[5]

Formation

Pentaphenylantimony can be formed by reacting dichlorotriphenylantimony with phenyl lithium.[1]

SbPh3Cl2 + 2 LiPh → SbPh5 + 2 LiCl

References

Further reading

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