Diboron tetrachloride

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Diboron tetrachloride
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Names
Preferred IUPAC name
Diboron tetrachloride
Systematic IUPAC name
Tetrachlorodiborane(4)
Identifiers
3D model (JSmol)
ChemSpider
PubChem CID
UNII
  • InChI=1S/B2Cl4/c3-1(4)2(5)6
    Key: LCWVIHDXYOFGEG-UHFFFAOYSA-N
  • InChI=1S/B2Cl4/c3-1(4)2(5)6
    Key: LCWVIHDXYOFGEG-UHFFFAOYAN
  • ClB(Cl)B(Cl)Cl
Properties
B2Cl4
Molar mass 163.42 g·mol−1
Appearancecolorless liquid
Density 1.5 g/cm3 (0 °C)
Melting point −92.6 °C (−134.7 °F; 180.6 K)
Boiling point 65.5 °C (149.9 °F; 338.6 K)
Thermochemistry
137.7 J/mol K
Std molar
entropy (S⦵298)
232.3 J/mol K
−523 kJ/mol
−468.8 kJ/mol
Related compounds
Related compounds
 Diboron tetrafluoride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Diboron tetrachloride is a tetrahalodiborane chemical compound with the formula B2Cl4. It is a colorless liquid. [1]

Contents

Synthesis

The modern synthesis involves dechlorination of boron trichloride using copper. [2] [ better source needed ]

It can also be formed by the electrical discharge procedure of boron trichloride at low temperatures: [1] [3]

BCl3 → BCl2 + Cl
Cl + Hg (electrode) → Hg2Cl2 or HgCl2
2 BCl2 → B2Cl4

The most efficient synthesis technique uses no dechlorinating metal, instead passing radio-frequency AC current through gaseous boron trichloride. [4]

Reactions

The compound is used as a reagent for the synthesis of organoboron compounds. For instance, diboron tetrachloride adds to ethylene: [5]

CH2=CH2 + B2Cl4 → Cl2B–CH2–CH2–BCl2

Diboron tetrachloride absorbs hydrogen quickly at room temperature: [3]

3 B2Cl4 + 3 H2 → B2H6 + 4 BCl3

With boranes, it replaces a hydrogen to form dichloroborane(3) and a polyhedral dichloroborane. Heat induces disproportionation back to boron trichloride and a polyhedral boron(I) chloride. [4]

References

  1. 1 2 P. L. Timms (1972). "Low Temperature Condensation". Advances in Inorganic Chemistry and Radiochemistry. Academic Press. p. 143. ISBN   0-12-023614-1.
  2. ↑ Timms, Peter L. (1979). "Tetrachlorodiborane(4) (Diboron Tetrachloride)". Inorganic Syntheses. Vol. 19. pp. 74–78. doi:10.1002/9780470132500.ch14. ISBN   9780470132500.
  3. 1 2 Urry, Grant; Wartik, Thomas; Moore, R. E.; Schlesinger, H. I. (1954). "The Preparation and Some of the Properties of Diboron Tetrachloride, B2Cl4". Journal of the American Chemical Society. 76 (21): 5293–5298. doi:10.1021/ja01650a010. ISSN   0002-7863.
  4. 1 2 Morrison, John A. (1991-01-01). "Chemistry of the polyhedral boron halides and the diboron tetrahalides". Chemical Reviews. 91 (1): 35–48. doi:10.1021/cr00001a003. ISSN   0009-2665.
  5. ↑ Urry, Grant; Kerrigan, James; Parsons, Theran D.; Schlesinger, H. I. (1954). "Diboron Tetrachloride, B2Cl4, as a Reagent for the Synthesis of Organo-boron Compounds. I. The Reaction of Diboron Tetrachloride with Ethylene". Journal of the American Chemical Society. 76 (21): 5299–5301. doi:10.1021/ja01650a011. ISSN   0002-7863.


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