Potassium tetracyanonickelate

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Potassium tetracyanonickelate
Potassium tetracyanonickelate.svg
Potassium tetracyanonickelate.jpg
Names
Other names
Potassium tetracyanonickelate(II); dipotassium tetracyanonickelate
Identifiers
  • 14220-17-8
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.034.605 Edit this at Wikidata
EC Number
  • 238-082-7
UNII
  • InChI=1S/4CN.2K.Ni/c4*1-2;;;/q4*-1;2*+1;+2
    Key: LXWJYIBQIPSFSE-UHFFFAOYSA-N
  • [C-]#N.[C-]#N.[C-]#N.[C-]#N.[K+].[K+].[Ni+2]
Properties
K2Ni(CN)4
Appearance yellow solid
Hazards
GHS labelling:
GHS06: ToxicGHS09: Environmental hazard
Signal word
 Danger
H300, H310, H330, H410
P260, P262, P264, P270, P271, P273, P280, P284, P301+P310, P302+P350, P304+P340, P310, P320, P321, P322, P330, P361, P363, P391, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Potassium tetracyanonickelate is the inorganic compound with the formula K2Ni(CN)4. It is usually encountered as the monohydrate but the anhydous salt is also known. Both are yellow, water-soluble, diamagnetic solids. The salt consists of potassium ions and the tetracyanonickelate coordination complex, which is square planar.[1]

Preparation[]

Ball-and-stick model of the tetracyanonickelate ion

Potassium tetracyanonickelate is prepared by treating aqueous solutions of nickel(II) salts with potassium cyanide. The synthesis is often conducted stepwise, precipitating the nickel dicyanide coordination polymer first. This route allows removal of excess potassium salts:[2]

Ni2+ + 2 KCN → Ni(CN)2 + 2 K+
Ni(CN)2 + 2 KCN → K2[Ni(CN)4]

This procedure yields the monohydrate. That solid dehydrates at 100 °C.

Reactions[]

The N-terminus of the cyanide ligand is basic and nucleophilic. The complex binds four equivalents of boron trifluoride:

K2[Ni(CN)4] + 4 BF3 → K2[Ni(CNBF3)4]

Cyanide is a sufficient pi-acceptor ligand to allow reduction of K2Ni(CN)4 to the Ni(0) derivative. Thus, potassium in anhydrous ammonia affords the tetraanionic, tetrahedral Ni(0) derivative [Ni(CN)4]4-.[3]

K2[Ni(CN)4] + 2 K → K4[Ni(CN)4]

An intermediate in this conversion is K4[Ni2(CN)6], which features an Ni-Ni bond.[4]

References[]

  1. ^ Vannerberg, Nils Gosta (1964). "The Crystal Structure of K2Ni(CN)4" (PDF). Acta Chemica Scandinavica. 18 (10): 2385–2391. doi:10.3891/acta.chem.scand.18-2385. Retrieved 29 April 2016. ICSD number 24099.
  2. ^ Fernelius, W. C.; Burbage, Joseph J. (1946). "Potassium Tetracyanonickelate(II)". Inorganic Syntheses. Inorganic Syntheses. 2. pp. 227–228. doi:10.1002/9780470132333.ch73. ISBN 9780470132333.
  3. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 426. ISBN 978-0-08-037941-8.
  4. ^ Jarchow, O.; Schulz, H.; Nast, R. (1970). "Structure of the Anion in Solid K4[Ni2(CN)6]". Angewandte Chemie International Edition in English. 9: 71. doi:10.1002/anie.197000711.
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