Pentaphenylantimony

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

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
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).
Infobox references

Properties

The solid is colourless and melts at 169-170°C.[1]

As a solid the pure form crystallises with a roughly square pyramidal shape. It can also form solvate complexes with cyclohexane or tetrahydrofuran—but not with diethyl ether—which form crystals with a trigonal bipyramid shape.[2] When dissolved, molecules are also trigonal bipyramidal.[2] However with nuclear magnetic resonance, in solution, the phenyl groups all appear to be equivalent. This is probably because the molecule is not stable in shape and orientation of phenyl changes rapidly.[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 reagents that replace one or more phenyl groups with a different substituent. Reagents with acidic hydrogen give benzene as byproduct, whereas dihalogens (or synthons of them) give the analogous halobenzene as byproduct:

Ph5Sb + HOR → PhH + Ph4SbOR
Ph5Sb + HX → PhH + Ph4SbX
Ph5Sb + X2 → PhX + Ph4SbX

For example, pentaphenylantimony reacts with dicarboxylic acids in solution, by substituting a phenyl group with the acid hydrogen. This yields a tetraphenyl antimony or bis(tetraphenyl antimony) compound.[4][5][6][7]

When heated, pentaphenylantimony forms triphenylstibine, biphenyl and p-quaterphenyl.[8]

Pentaphenylantimony reacts with bromine to make bromobenzene and tetraphenylstibonium bromide. With hydrogen bromide, tetraphenylstibonium bromide along with benzene is the result. Pentaphenylantimony reacts with methanol to make methoxytetraphenylantimony and dimethoxytriphenylantimony. A reaction with carbon tetrachloride yields tetraphenylstibonium chloride, chlorobenzene, and benzene. All these reactions appear to involve forming the phenyl radical.[8]

Formation

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

References
  1. Beauchamp, A. L.; Bennett, Michael J.; Cotton, F. Albert (November 1968). "A reinvestigation of the crystal and molecular structure of pentaphenylantimony". Journal of the American Chemical Society. 90 (24): 6675–6680. doi:10.1021/ja01026a020.
  2. Lindquist-Kleissler, Brent; Weng, Monica; Le Magueres, Pierre; George, Graham N.; Johnstone, Timothy C. (2021-06-21). "Geometry of Pentaphenylantimony in Solution: Support for a Trigonal Bipyramidal Assignment from X-ray Absorption Spectroscopy and Vibrational Spectroscopic Data". Inorganic Chemistry. 60 (12): 8566–8574. doi:10.1021/acs.inorgchem.1c00496. ISSN 0020-1669. PMID 34087066. S2CID 235346648.
  3. Beattie, I. R.; Livingston, K. M. S.; Ozin, G. A.; Sabine, R. (1972). "The shape of pentaphenylantimony and pentaphenylarsenic in solution". Journal of the Chemical Society, Dalton Transactions (7): 784. doi:10.1039/DT9720000784.
  4. Sharutin, Vladimir V.; Sharutina, Olga K.; Pakusina, Antonida P.; Belsky, Vitaly K. (May 1997). "Reactions of pentaphenylantimony with dicarboxylic acids". Journal of Organometallic Chemistry. 536–537: 87–92. doi:10.1016/S0022-328X(96)06463-7.
  5. Sharutin, V. V.; Sharutina, O. K.; Gubanova, Yu. O.; El'tsov, O. S. (September 2019). "Specific Features of the Reaction between Pentaphenylantimony and Bifunctional Acids: Structures of Bis(tetraphenylantimony) Glutarate, Benzene Solvate of Bis(tetraphenylantimony) 1,4-Cyclohexanedicarboxylate, Dioxane Solvate of Triphenylantimony Hydroxybenzoate, and Triphenylantimony 3-Hydroxybenzoate Adduct with Tetraphenylantimony Tetraphenylstiboxybenzaote and Toluene". Russian Journal of Inorganic Chemistry. 64 (9): 1138–1145. doi:10.1134/S0036023619090195. S2CID 203852991.
  6. Sharutin, Vladimir V.; Sharutina, Olga K.; Gubanova, Yulia O.; Bregadze, Vladimir I.; Glazun, Sergey A. (December 2015). "Interaction of pentaphenylantimony with carboranedicarboxylic acid". Journal of Organometallic Chemistry. 798: 41–45. doi:10.1016/j.jorganchem.2015.09.002.
  7. Razuvaev, G.; Sharutin, V (2015). "Some reactions of bis(cyclopentadienyl)diferrocenyltitan". "Bulletin of the South Ural State University Series "Chemistry"". 15 (4): 9–12. doi:10.14529/chem150403.
  8. Shen, Kei-Wei; McEwen, William E.; Wolf, Alfred Peter (March 1969). "Photolysis and thermolysis of pentaphenylantimony in benzene". Journal of the American Chemical Society. 91 (6): 1283–1288. doi:10.1021/ja01034a003.

Extra reading
  • Smirnova, N.N.; Letyanina, I.A.; Larina, V.N.; Markin, A.V.; Sharutin, V.V.; Senchurin, V.S. (January 2009). "Thermodynamic properties of pentaphenylantimony Ph5Sb over the range from T→0K to 400K". The Journal of Chemical Thermodynamics. 41 (1): 46–50. doi:10.1016/j.jct.2008.08.002.
  • Brock, C. P.; Ibers, J. A. (1976-01-01). "The role of crystal packing forces in the structure of pentaphenylantimony". Acta Crystallographica Section A. 32 (1): 38–42. Bibcode:1976AcCrA..32...38B. doi:10.1107/S0567739476000065.
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