Hafnium (IV) chloride

Crystal structure
__ Hf 4+      __ Cl -
General
Surname	Hafnium (IV) chloride
other names	Hafnium tetrachloride
Ratio formula	HfCl 4
Brief description	white solid
External identifiers / databases
CAS number 13499-05-3 EC number 236-826-5 ECHA InfoCard 100.033.463 PubChem 37715 ChemSpider 34591 Wikidata Q2628977
properties
Molar mass	320.30 g mol −1
Physical state	firmly
Melting point	432 ° C (enclosed under own pressure)
Sublimation point	315 ° C
Vapor pressure	1 hPa (190 ° C)
solubility	reacts with water
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 314 P: 280-305 + 351 + 338-310
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Hafnium (IV) chloride is an inorganic chemical compound of hafnium from the group of chlorides .

Extraction and presentation

Hafnium (IV) chloride can be obtained by chlorinating hafnium with chlorine at 320 ° C.

${\displaystyle \mathrm {Hf+2\ Cl_{2}\longrightarrow HfCl_{4}} }$

Hafnium (II) hydride can also be obtained by reacting with hydrogen chloride .

${\displaystyle \mathrm {HfH_{2}+4\ HCl\longrightarrow HfCl_{4}+3\ H_{2}} }$

Another possibility is the representation by reacting the oxide with gaseous carbon tetrachloride (in a nitrogen stream) at 450 ° C to 500 ° C:

${\displaystyle {\ce {HfO2 + 2 CCl4 -> HfCl4 + 2 COCl2}}}$

properties

Hafnium (IV) chloride is a hygroscopic, white crystalline powder that forms hydrochloric acid mist in moist air and is vigorously decomposed by water, producing hafnium oxychloride .

${\displaystyle \mathrm {HfCl_{4}+H_{2}O\longrightarrow HfOCl_{2}+2\ HCl} }$

It sublimes at 315 ° C and melts under pressure at 432 ° C. The crystal structure of the compound is monoclinic with the space group P 2 / c (space group no. 13) and is composed of slightly distorted HfCl ₆ - octahedra which extended cis-linked HfCl ₂ Cl _4/2 form chains.

use

Hafnium (IV) chloride is used as the starting compound for the chemical vapor deposition of hafnium carbide .

Individual evidence

1. ↑ ^{a b c d} Georg Brauer (Ed.), With the collaboration of Marianne Baudler a . a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume II, Ferdinand Enke, Stuttgart 1978, ISBN 3-432-87813-3 , p. 1358.
2. ↑ ^{a b c d e} data sheet Hafnium (IV) chloride, purified by sublimation, 99.9% trace metals basis from Sigma-Aldrich , accessed on May 3, 2013 ( PDF ).
3. ↑ ^{a b c} W. S. Hummers et al .: Zirconium and hafnium tetrachlorides . In: JC Bailar, Jr. (Ed.): Inorganic Syntheses . tape 4 . McGraw-Hill, Inc., 1953, pp. 121-126 (English).
4. ^ ^{A b} Mark D. Allendorf: Proceedings of the Symposium on Fundamental Gas Phase and Surface Chemistry ... The Electrochemical Society, 1999, ISBN 1-56677-217-6 , pp. 265 ( limited preview in Google Book search).
5. ↑ R. Niewa and H. Jacobs (1995). Crystal structure of hafnium (IV) chloride, HfCl ₄ . Journal of Crystallography - Crystalline Materials: Vol. 210, No. 9, pp. 687-687. doi : 10.1524 / zkri.1995.210.9.687