A Comprehensive Treatise on Inorganic and Theoretical Chemistry

260 INORGANIC AND THEORETICAL, CHEMISTRY
when extracted with water leaves a basic salt undissolved. S. Gr. Hedin reported
the possible existence of platinous difluorobispyridine, [Pt(C5H5N)2F2].
C. Poulenc observed that platinum tetrafluoride or platinic fluoride, PtF4,
cannot be obtained by heating platinum tetrachloride in hydrogen fluoride ; since,
according to W. Jeroch, and O. Ruff and W. Jeroch, only dark brown, anhydrous
platinic chloride is formed below 20O 0 ,. and over 220°, the platinic chloride
decomposes into its constituent elements. Nor was platinum tetrafluoride
obtained by heating platinum tetrachloride with molten potassium hydrofluoride
at 280°. H. Moissan prepared the tetrafluoride by heating a bundle of
platinum wire to dull redness in a platinum or fluorspar tube through which a
current of fluorine is passed. As soon as combination is complete, the product is
transferred to a dry tube. G. Gore observed that some of this salt is formed when
silver fluoride is melted with iodine in a platinum vessel ; and O. Ruff and J. Zedner,
when fluorine is passed over columbium in a platinum vessel.
Platinum tetrafluoride furnishes a deep red, fused mass, or chamois-yellow
crystals resembling those of anhydrous platinum tetrachloride. The salt is
extremely hygroscopic, and cannot be kept for a long time in a dried but corked
tube. It decomposes at a red-heat, forming crystals of platinum ; and when heated
in a glass vessel, the glass is energetically decomposed to form platinum and silicon
tetrafluoride. When treated with a small proportion of water, a tawny coloration
is first produced, then heat is rapidly developed, and the salt is decomposed -with
the formation of hydrofluoric acid and hydrated platinum dioxide. Very dil.
soln. are more stable, but they behave similarly if the liquid is warmed. This
hydrolysis shows why platinic fluoride cannot be prepared by the action of hydrofluoric
acid on hydrated platinum dioxide ; and renders it questionable if
J. J. Berzclius' preparation was what it "was thought to be. The fact that fluorine
containing hydrogen fluoride attacks platinum more vigorously than fluorine alone ;
and the existence of double salts with the alkali metals made H. Moissan suggest that
possibly a platinic hydrofluoride, PtF4.nHF, can be formed. Platinic fluoride forms
crystalline compounds with the fluorides and chlorides of phosphorus and boron.
J. J. Berzelius obtained a dark brown, gummy mass from a mixture of his
platinum fluoride and ammonium fluoride. The product was resolved by water
into a soluble acidic salt, and an insoluble basic salt. It was insoluble in alcohol.
According to C. Poulenc, there is a state of equilibrium between ammonium
fluoride and platinic chloride in the molten state, some ammonium fluoplatinate,
probably (NH4)2PtF6, is formed, but it cannot be separated from the chloroplatinate
-which is associated with it. C. Poulenc obtained it by the action of ammonium
fluoride on hydrated platinum dioxide, and the compound is not decomposed -when
heated to 300° in a current of hydrogen fluoride, but it is decomposed at a higher
temp, to form platinum, platinum tetrafluoride, etc.
J. J. Berzelius obtained potassium fluoplatinate, K2PtF6, by treating a soln.
of potassium fluoride "with less than an eq. quantity of hydrochloroplatinic acid,
decanting the liquid from the precipitated potassium chloroplatinate, and evaporating.
The dark brown, deliquescent salt is insoluble in alcohol. H. I. Schlessinger
and M. W. Tapley obtained it by heating finely-divided platinum with the lead
salt 3KF.HF.PbF4, and they studied the absorption spectra. J. J. Berzelius also
reported sodium fluoplatinate to be a dark brown, gum-like mass which is hydrolyzed
by water into a soluble acidic salt, and an insoluble basic salt.
REFERENCES .
1 J. J. Berzelius, Lehrbuch der Chemie, Dresden, 2. ii, 953, 1826 ; SchiveiggeSs Journ., 7.
65, 1816 ; 34. 81, 1821 ; G. Gore, Ghent. News, 23. 13, 1871 ; S. G. Hedin, Om pyridinens platina,baser,
Lund, 1886 ; JLunds Arsskr., (2), 22. 3, 1887 ; W. Jeroch, Versuche zur Darstellung van
EdelmetaUflttoriden, Berlin, 1906 ; H. Moissan, Cornpt. Rend., 109. 807, 1889 ; Bull. Soc. Chim.,
(3), 5. 454, 1891 ; Ann. Chim. Phys., (6), 24. 282, 1891 ; C. Poulenc, ib.t (7), 2. 74, 1894 ; O. Ruff
and W. Jeroch, Ber., 46. 922, 1913 ; O. Ruff and J. Zedner, ib., 42. 493, 1909 : H. I. Schlessinger
and M. W. Tapley, Journ. Amer. Chem. Soc, 46. 276, 1924.