Platinum (IV) oxide

Crystal structure
__ Pt 4+      __ O 2−
General
Surname	Platinum (IV) oxide
other names	Platinum dioxide Adam's catalyst
Ratio formula	PtO 2
Brief description	black solid (anhydrous)
External identifiers / databases
CAS number 1314-15-4 (anhydrous) 52785-06-5 (hydrate) EC number 215-223-0 ECHA InfoCard 100,013,840 PubChem 345198 ChemSpider 306130 Wikidata Q1851782
properties
Molar mass	227.077 g mol −1
Physical state	firmly
density	11.8 g cm −3
Melting point	450 ° C (decomposes to PtO )
solubility	almost insoluble in water and alkalis
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 272-319 P: 220-305 + 351 + 338
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Platinum (IV) oxide , also known as platinum dioxide , is a chemical compound of the elements platinum and oxygen . It is a black solid, and decomposes at 450 ° C in platinum (II) oxide .

Because of its use as a catalyst in organic chemistry, it is also known as the Adams catalyst, according to Roger Adams .

Extraction and presentation

Depending on the experimental conditions, platinum dioxide is obtained as a dark brown PtO ₂ · H ₂ O containing hydrate or as a black crystalline solid PtO ₂ . Hexachloridoplatinic acid H ₂ [PtCl ₆ ] or ammonium hexachloridoplatinate (IV) (NH ₄ ) ₂ [PtCl ₆ ] serves as the starting substance for the representation . These substances are converted into the desired product in a sodium nitrate melt:

${\displaystyle \mathrm {H_{2}PtCl_{6}+6\ NaNO_{3}\longrightarrow \ PtO_{2}+4\ NO_{2}+6\ NaCl+2\ HNO_{3}} }$

properties

Physical Properties

Platinum dioxide crystallizes in the trigonal crystal system with the space group P 3 m 1 (space group no. 164) and the lattice parameters a = 310.0 pm, and c = 414.0 pm (2H type of CdI ₂ structure), in the unit cell is a formula unit . A β form of platinum dioxide has an orthorhombic crystal structure of the CaCl ₂ type, which is close to the tetragonal rutile type (see figure; space group Pnnm (No. 58) ).

Chemical properties

When heated, platinum dioxide gives off oxygen and changes to platinum monoxide at 450 ° C , which in turn breaks down into the elements at 950 ° C.

${\displaystyle \mathrm {2\ PtO_{2}\ \ {\xrightarrow[{-O_{2}}]{450^{\circ }C}}\ \ 2\ PtO\ \ {\xrightarrow[{-O_{2}}]{950^{\circ }C}}\ \ 2\ Pt} }$

use

Platinum dioxide hydrate is used as a hydrogenation catalyst .

Individual evidence

1. ↑ ^{a b c} David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Properties of the Elements and Inorganic Compounds, pp. 4-81.
2. ^ ^{A b} A. F. Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , pp. 1732-1733.
3. ↑ ^{a b} Datasheet Platinum (IV) oxide from Sigma-Aldrich , accessed on April 21, 2011 ( PDF ).
4. ↑ Georg Brauer (ed.) U. a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume III, Ferdinand Enke, Stuttgart 1981, ISBN 3-432-87823-0 , pp. 1717-1718.
5. ^ Jean D'Ans, Ellen Lax: Pocket book for chemists and physicists. 3. Elements, inorganic compounds and materials, minerals, Volume 3. 4. Edition, Springer, 1997, ISBN 978-3-540-60035-0 , p. 678 ( limited preview in the Google book search).