A Comprehensive Treatise on Inorganic and Theoretical Chemistry

PLATINUM
the cold soln. from the platinous diamminodichloride ; added potassium chloroplatinite
and filtered from the platinous tetramminochloroplatinite and evaporated
the soln., and obtained a yield of 2*70 grms. of platinous chlorotriamminochloroplatinite
in rose-red, lustrous plates or scales. The general methods depend on
adding ammonia to the dichlorodiammine, or removing ammonia from the tetramminochloride.
L. Tschugaeff prevented the ammonation of the dichlorodiammine
being carried too far, by employing potassium cyanate which evolves ammonia
gradually when hydrolyzed :
One grm. of platinous cis-dichlorodiammine (Peyrone's chloride) is boiled with 0-7 grm.
of potassium cyanato and 18 to 20 c.c. of water. After soln. is complete the boiling is
continued for one minute. Several portions prepared in this "way are combined, and
heated with an excess of hydrochloric acid, sp. gr. 1-19 (4 c.c. for each portion) ; the
whole is then heated to boiling, and cooled. After collecting the unchanged dichlorodiammine
which separates, an excess of potassium chloroplatmite is added to the filtrate,
whereby a mixture of platmotis tetramminochloroplatinite and of platinous ehlorotriamminochloroplatinito
is formed. This mixture is then separated by taking advantage of
the fact that the latter compound is fairly readily soluble in hot water. The yiold of ehloroplatinite
thus obtained is about 50 per cent, of the theoretical, calculated on tho dichlorodiammine
which enters into reaction.
"K. Gr. Cox and co-workers found that the pink salt of Magnus is formed only
under special conditions, and that the salt usually called the pink salt of Magnus
is really Cleve's salt. The X-radiograms of the two salts are very similar. The
c-axes of the two are equal, and the a-axis of Cleve"s salt is probably 3 or 3/\/2
times that of the te tram mine salt.
A. R. Klien studied the action of water, acids, and alkalies on the salt. Platinous
chlorotriamminochloroplatinite is soluble in cold water, and freely soluble in
boiling water ; it is not decomposed by boiling water ; ammonia transforms it
into platinous tetramminochloroplatinite ; nitric acid yields platinic chlorodinitratotriamminochloride
; silver nitrate precipitates silver chloroplatinite, and
forms a soln. of platinous nitratotriamminonitrate ; silver sulphate forms platinous
sulphatotriammine ; potassium permanganate in a boiling soln. forms platinous
chlorotriamminochloroplatinate, [Pt(NH3)4Cl IPtCl6, with sodium chloroplatinate.
A. Cossa observed that there is formed platinous chlorotriamminochloroplatinate.
M. Peyrone prepared platinous cMorotriamminotrichloroamminoplatinite,
I Pt(NH3)aCl J[Pt(NH3)Cl3J.
W. Odlmg « prepared yellow platinous //aw,s dichlorodiammine, [Pt(NH3)2Cl2],
by the action of hydrochloric acid on the corresponding hydroxide, Kciset's second
base ; and also by the action of ammonia on platinous chloride. This salt has
also been called Reiset 9 s chloride, and platinous a-dichlorodiammine. J. Reiset,
M. Peyrone, P. T. Cleve, and L. Ramberg prepared it by heating platinous tetrammhiochloride
to 250° as long as ammonia is evolved, and until a white cloud of
ammonium chloride appears. The residue can be crystallized twice from hot water,
or transformed into the nitrate, by treatment with silver nitrate, and the filtrate
treated with hydrochloric acid. Just as J. Reiset obtained the salt by heating
platinous dinitrato- or sulphato-diammine with hydrochloric acid or alkali chloride,
M. Peyrone evaporated to dryness a mixture of platinous tetramminochloride and
an excess of cone, hydrochloric acid, and extracted the ammonium chloride with
water ; and J. Reiset, also, by boiling platinous tetramminochloroplatinite for a long
time with a soln. of ammonium nitrate, sulphate, or chloride, and cooling the
liquid. A. Cossa observed that some [Pt(NHg)4][Pt(NH3)CIg)2, previously described,
is formed. S. M. Jorgensen found that dichlorodiammine is formed in the thermal
decomposition of ammonium chloroplatinite at 170°. H. and W. Biltz recommended
the following process :
Heat about 0*3 grm. of platinous tetramminochloride to 250° in a test-tube immersed
in a paraffin bath. If any •water is given off, stop the heating to remove tho drops, condensed
on the upper walls of the test-tube, by a strip of filter-paper. Continue tho heating
until ammonia is evolved, the substance becomes dark coloured, and a brittle platinum
261