Chemical elements
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      Platinum Difluoride
      Platinum Tetrafluoride
      Platinum Dichloride
      Tetrachlor~platinous Acid
      Tetrachlor-platinites
      Potassium Tetrachlor-platinite
      Trichlor-hydroxy-platinous Acid
      Silver Trichlor-hydroxy-platinite
      Platinum Trichloride
      Caesium Pentachlor-platinite
      Platinum Tetrachloride
      Ammonium Chlor-platinate
      Caesium Chlor-platinate
      Potassium Chlor-platinate
      Rubidium Chlor-platinate
      Silver Chlor-platinate
      Sodium Chlor-platinate
      Pentachlor-hydroxy-platinic Acid
      Barium Pentachlor-hydroxy-platinate
      Silver Pentachlor hydroxy-platinate
      Tetrachlor-dihydroxy-platinic Acid
      Dichlor-tetrahydroxy-platinic Acid
      Monochlor-pentahydroxy-platinic Acid
      Platinum Dibromide
      Brom platinous Acid
      Brom-platinic Acid
      Platinum Di-iodide
      Platinum Tetra-iodide
      Iodo-platinic Acid
      Ammonium Iodoplatinate
      Potassium Iodo-platinate
      Sodium Iodo-platinate
      Tetra-iodo-dihydroxy-platinic Acid
      Platinum Monoxide
      Triplatinum Tetroxide
      Platinum Sesquioxide
      Platinum Dioxide
      Hexahydroxy-platinic Acid
      Platinum Trioxide
      Platinum Monosulphide
      Platinum Sesquisulphide
      Platinum Disulphide
      Potassium Thio-platinate
      Platinum Oxysulphide
      Platinum Disulphate
      Platinum Monoselenide
      Platinum Triselenide
      Platinum Subtelluride
      Platinum Monotelluride
      Platinum Ditelluride
      Ammonium Platinonitrite
      Potassium Platinonitrite
      Silver Platinonitrite
      Platinum Subphosphide
      Platinum Monophosphide
      Platinum Diphosphide
      Platinum Arsenide
      Platinum Di-antimonide
      Monocarbonyl Platinum Dichloride
      Sesquicarbonyl Platinum Dichloride
      Dicarbonyl Platinum Dichloride
      Diphosgene Platinum Dichloride
      Carbonyl Platinum Dibromide
      Monocarbonyl Platinum Di-iodide
      Carbonyl Platinum Monoxide
      Carbonyl Platinum Monosulphide
      Carbonyl Platinum Thiocyanate
      Platinous Cyanide
      Cyanoplatinous Acid
      Platinocyanides
      Aluminium Platinocyanide
      Ammonium Platinocyanide
      Barium Platinocyanide
      Calcium Platinocyanide
      Cerium Platinocyanide
      Copper Platinocyanide
      Hydrazine Platinocyanide
      Hydroxylamine Platinocyanide
      Indium Platinocyanide
      Lead Platinocyanide
      Magnesium Platinocyanide
      Potassium Platinocyanide
      Radium Barium Platinocyanide
      Rubidium Platinocyanide
      Sodium Platinocyanide
      Sodium Potassium Platinocyanide
      Strontium Platinocyanide
      Uranyl Platinocyanide
      Dichlorcyanoplatinic Acid
      Cyanoplatinic Acid
      Lithium Platinicyanide
      Potassium Platinicyanide
      Silver Platinicyanide
      Potassium Thiocyanoplatinite
      Ammonium Thiocyanoplatinate
      Potassium Thiocyanoplatinate
      Potassium Selenocyanoplatinate
      Platinum Subsilicide
      Platinum Monosilicide
    Catalyst
    PDB 1a2e-2bho
    PDB 2ch8-3un9
    PDB 3vdk-5bna

Barium Platinocyanide, BaPt(CN)4






Barium Platinocyanide, BaPt(CN)4.4H2O, is one of the most useful platinocyanides, inasmuch as it may be conveniently used in preparing other salts of hydrogen platinocyanide. Quadrat was the first to prepare it by boiling the copper derivative with barium hydroxide solution. Schafarik obtained it by decomposing barium carbonate with free platinocyanic acid. Martius boiled platinous cyanide with barium cyanide solution and obtained the salt, but recommended the following method as superior: Pulverised platinous chloride, PtCl2, is added little by little to a boiling solution of barium cyanide in such a manner that no fresh chloride is added until the previous amount has completely dissolved and the solution become colourless. On crystallisation the salt is obtained in a very pure condition.

By electrolysis of a solution of barium cyanide between platinum electrodes, using an alternating current, a solution of barium platino-cyanide has been obtained which, upon concentration, crystallised out in yellow, slightly dichroic crystals, exhibiting a slight fluorescence under radium.

The salt may also be obtained by passing gaseous hydrogen cyanide into a pasty mixture of two parts of platinum dichloride and three of freshly precipitated barium carbonate with ten of water, maintained at nearly the boiling-point. The passage of gas is continued until effervescence ceases, and the solution is then boiled and filtered whilst hot. On cooling, the barium platinocyanide crystallises out in golden yellow, transparent crystals, exhibiting a purple sheen. The crystals frequently exhibit red and green colours on the edges, this effect being particularly noticeable when they are immersed in water. The crystals belong to the monoclinic system, the crystallographic elements being:

a: b: с = 0.86928: 1: 0.47928. β = 103° 54'

At 100° C. the salt loses two molecules of water, and becomes anhydrous at 140°-150° C., a yellowish blue powder remaining, which readily absorbs moisture on exposure to the air. The salt readily dissolves in hot water, but is insoluble in absolute alcohol.

Barium platinocyanide tetrahydrate can exist in two isomeric forms, which, however, are crystallographically identical. They differ in colour, density, and in fluorescence, as indicated in the following table:

α-saltβ-salt
ColourGolden yellowApple-green
Density at 17° C2.0762.085
FluorescenceFeebleIntense
StabilityLess stable at the ordinary temperatureMore stable at the ordinary temperature
Crystalline characterSame as β-saltSame as α-salt


When a solution of barium platinocyanide is allowed to crystallise after adding a trace of barium cyanide or barium hydroxide to it, crystals of th,e green β-salt are obtained. If, on the other hand, a trace of hydrogen cyanide, hydrogen chloride, tartaric or acetic acid, or cyanoplatinous acid is present instead, crystals of the yellow α-salt are deposited.

The β-salt appears to be the more stable at ordinary temperatures.

The dihydrate and the anhydrous salt have also been prepared. The former is brick-red in colour and non-fluorescent. The latter is white and but feebly fluorescent.

Barium platinocyanide, after prolonged exposure to radiation from radium compounds, becomes brown or red and loses its fluorescent properties. The only way to completely restore the red crystals to their fluorescent state is by solution and recrystallisation, although gentle heating will partially restore them. This is well illustrated by the following table:

Fluorescent Value
1Fresh crystals100
2Fresh crystals after exposure to β-rays from radium for eight hours8
3Fresh crystals after exposure to β-rays from radium for forty-eight hours8
4Red crystals (No. 3 above) after heating to 110° C. in open tube27
5Red crystals after heating to 120° C. in sealed tube33


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