Zirconium (IV) borohydride

Structural formula
General
Surname	Zirconium (IV) borohydride
other names	Zirconium (IV) borohydride Zirconium boronate
Molecular formula	Zr (BH 4 ) 4
External identifiers / databases
CAS number 23840-95-1 Wikidata Q25393302
properties
Molar mass	150.59 g mol −1
Physical state	solid to liquid
Melting point	28.7 ° C
boiling point	123 ° C
safety instructions
GHS hazard labeling no classification available
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Zirconium (IV) borohydride is a chemical compound from the group of zirconium compounds and boranes .

Extraction and presentation

The synthesis takes place through the reaction of lithium borohydride with zirconium (IV) chloride .

${\displaystyle \mathrm {4\,LiBH_{4}+ZrCl_{4}\rightarrow Zr(BH_{4})_{4}+4\,LiCl} }$

properties

Structure of Zr (BH ₄ ) ₄

Zirconium (IV) borohydride is a low-melting solid and a volatile liquid above its melting point. The low melting point at 28.7 ° C and the low boiling point at 123 ° C indicate a complex compound instead of an ionic salt compound. The determination of the crystal structure revealed a highly coordinated structure, three of the hydrogen atoms of the boronate units being coordinated with the central ion. The thermal decomposition of the compound above 250 ° C. gives a product with the composition ZrB _2.76-3.74 , the crystalline phase consisting of zirconium diboride and the remainder of amorphous boron . In the gas phase, the decomposition takes place according to:

${\displaystyle \mathrm {Zr(BH_{4})_{4}\rightarrow ZrB_{2}+B_{2}H_{6}+5\,H_{2}} }$

The compound is pyrophoric , it self-ignites in the presence of air, whereby the ignition can be delayed with an explosion. Rapid hydrolysis occurs in the presence of water.

use

The compound serves as a starting material for the production of zirconium diboride ZrB ₂ , which can be used for high-temperature ceramics or for coating glass or metal surfaces. It is used as an effective reducing agent in organic chemistry. The compound has also been proposed as a hydrogen storage material.

Web links

Commons : Zirconium borohydride  - collection of images, videos and audio files

Individual evidence

1. ↑ ^{a b c d e f} Roth / Weller: Hazardous chemical reactions , ecomed SECURITY, Hüthig Jehle Rehm publishing group, edition 08/2011.
2. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
3. ↑ ^{a b} Rice, GW; Woodin, RL: Zirconium Borohydride as a Zirconium Boride Precursor in J. Am. Ceramic Soc. 71 (1988) c181-c183, doi : 10.1111 / j.1151-2916.1988.tb05867.x .
4. ↑ Bird, PH; Churchill, MR: The crystal structure of zirconium (IV) borohydride (at -160 °) in Chem. Commun. (London), 1967, 403, doi : 10.1039 / C19670000403 .
5. ↑ Andrievskii, RA; Kravchenko, SE; Shilkin, SP: Preparation and some properties of ultrafine zirconium boride and titanium boride powders in Inorganic Materials (Translation of Neorganicheskie Materialy) 31 (1995) 965-968.
6. ↑ ^{a b} Jensen, J A .; Gozum, JE; Pollina, DM; Girolami, GS: Titanium, zirconium, and hafnium tetrahydroborates as "tailored" CVD precursors for metal diboride thin films in J. Am. Chem. Soc. 110 (1988) 1643-1644, doi : 10.1021 / ja00213a058 .
7. ↑ Narasimhan, S .; Balakumar, R .: Zirconium Borohydride - a Versatile Reducing Agent for the Reduction of Electrophilic and Nucleophilic Substrates in Synth. Comm. 30 (2000) 4387-4395, doi : 10.1080 / 00397910008087061 .
8. ↑ Soloveichik, GL: Metal Borohydrides as Hydrogen Storage Materials in Material Matters 2007, 2.2, 11.