Silver cyanate

Structural formula
General
Surname	Silver cyanate
other names	cyanate silver Silver (I) cyanate
Molecular formula	AgOCN
Brief description	beige to gray powder
External identifiers / databases
CAS number 3315-16-0 EC number 222-006-4 ECHA InfoCard 100.020.007 PubChem 516935 Wikidata Q1429870
properties
Molar mass	149.88 g mol −1
Physical state	firmly
density	4.0 g cm −3 (25 ° C)
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 302-312-332 P: 280
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Silver cyanate is the cyanate salt of silver with the formula AgOCN; it is isomeric with silver fulminate (AgONC), the salt of acidic acid . Justus Liebig and Friedrich Wöhler discovered isomerism in these two connections in the 1820s .

Extraction and presentation

Silver cyanate can be obtained by reacting potassium cyanate or urea with silver nitrate .

${\displaystyle \mathrm {AgNO_{3}+KOCN\longrightarrow AgOCN\downarrow +\ KNO_{3}} }$

${\displaystyle \mathrm {AgNO_{3}+H_{2}N{\text{-}}C(O){\text{-}}NH_{2}\longrightarrow } }$ ${\displaystyle \mathrm {AgOCN\downarrow +\ NH_{4}NO_{3}} }$

The second reaction equation corresponds to the reverse reaction of the first synthesis of urea in 1828 by Friedrich Wöhler.

properties

Silver cyanate is a beige to gray powder. It crystallizes in the monoclinic crystal system in the space group P 2 ₁ / m with the lattice parameters a = 547.3  pm , b = 637.2 pm, c = 341.6 pm and β = 91 °. In the unit cell contains two formula units . According to this crystal structure, the nitrogen atoms of the cyanate anion bridge two silver atoms, resulting in a zigzag chain with linearly coordinated silver atoms. The Ag-N distance is 211.5 pm. The oxygen atoms coordinate only weakly with the silver atoms of the next zigzag chain. The Ag-O distance is correspondingly long at 299.6 pm. For comparison: the Ag-O distance in silver (I) oxide is 205 pm.

Silver cyanate is decomposed by the action of acids, producing carbon dioxide and the corresponding ammonium salt:

${\displaystyle \mathrm {AgOCN+2HNO_{3}+H_{2}O\longrightarrow } }$

${\displaystyle \mathrm {AgNO_{3}+CO_{2}\uparrow +\ NH_{4}NO_{3}} }$

Individual evidence

1. ↑ ^{a b c d} data sheet Silver cyanate, 99% from Sigma-Aldrich , accessed on December 13, 2011 ( PDF ).
2. ↑ Willy Kühne: Textbook of Physiological Chemistry . 1868 ( page 470 in the Google book search).
3. ^ D. Britton, JD Dunitz: The crystal structure of silver cyanate , Acta Cryst. (1965). 18, 424-428, doi : 10.1107 / S0365110X65000944
4. ^ LE Sutton: Interatomic Distances. , London: The Chemical Society (1958).
5. ↑ J. Milbauer: Determination and separation of cyanates, cyanides, rhodanides and sulfides in Fresenius' Journal of Analytical Chemistry 42 (1903) 77-95, doi : 10.1007 / BF01302741 .