Arsenic pentachloride

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Arsenic pentachloride
Ball-and-stick model of a single molecule
Ball-and-stick model of the crystal structure
Molar mass 252.1866 g/mol
US health exposure limits (NIOSH):
PEL (Permissible)
[1910.1018] TWA 0.010 mg/m3[1]
REL (Recommended)
Ca C 0.002 mg/m3 [15-minute][1]
IDLH (Immediate danger)
Ca [5 mg/m3 (as As)][1]
Trigonal Bipyramidal (D3h)
Related compounds
Related group 5 chlorides
Phosphorus pentachloride
Antimony pentachloride
Related compounds
Arsenic pentafluoride
Arsenic trichloride
Arsenic pentoxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY verify (what is YesYN ?)
Infobox references

Arsenic pentachloride is a chemical compound of arsenic and chlorine.[2] This compound was first prepared in 1976 through the UV irradiation of arsenic trichloride, AsCl3, in liquid chlorine at −105 °C.[3] AsCl5 decomposes at around −50 °C. The structure of the solid was finally determined in 2001.[4] AsCl5 is similar to phosphorus pentachloride, PCl5 in having a trigonal bipyramidal structure where the equatorial bonds are shorter than the axial bonds (As-Cleq = 210.6 pm, 211.9 pm; As-Clax= 220.7 pm).

The pentachlorides of the elements above and below arsenic in group 15, phosphorus pentachloride and antimony pentachloride are much more stable and the instability of AsCl5 appears anomalous. The cause is believed to be due to incomplete shielding of the nucleus in the elements following the first transition series (i.e. gallium, germanium, arsenic, selenium, bromine, and krypton) which leads to stabilisation of their 4s electrons making them less available for bonding. This effect has been termed the d-block contraction and is similar to the f-block contraction normally termed the lanthanide contraction.


  1. ^ a b c "NIOSH Pocket Guide to Chemical Hazards #0038". National Institute for Occupational Safety and Health (NIOSH). 
  2. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9. 
  3. ^ K. Seppelt (1976). "Arsenic Pentachloride, AsCl5". Angew. Chem. Int. Ed. Engl. 15 (6): 377–378. doi:10.1002/anie.197603771. 
  4. ^ Haupt S, Seppelt K (2002). "Solid State Structures of AsCl5 and SbCl5". Zeitschrift für anorganische und allgemeine Chemie. 628 (4): 729–734. doi:10.1002/1521-3749(200205)628:4<729::AID-ZAAC729>3.0.CO;2-E.