A Comprehensive Treatise on Inorganic and Theoretical Chemistry

PLATINUM 371
mass by water, a little platinous bromide remains undissolved.- L. Wohler and
F. Miiller obtained the anhydrous tetrabromide by heating bromoplatinic acid in a
current of bromine at 300° ; at 370° the tribromide is formed, and at 405° to 410°,
the dibromide. The dibromide is thus difficult to prepare because it is stable over
a temp, range of 5°. A. Gutbier observed that platinous bromide is formed when
platinic bromide is heated to 180° ; and W. Halberstadt, and H. Topsoe, when
hydrobromoplatinic acid is heated to 100°, or more rapidly at 200°. W. Halberstadt
observed that the bromide is formed in the electrolysis of a cone. soln. of platinic
bromide ; and M. Katayama, during the working of the cell : Pb|PbBrsoiid|Br
(and platinum).
W. Pullinger observed that platinous bromide is black if it has not been heated
over 180°, and dark brown if prepared at 250°. W. Halberstadt, and H. Topsoe
said that the bromide forms a greenish-brown powder. R. Klement gave 6*652 for
the sp. gr. at 25°/4°, and 53*4 for the mol. vol. H. Topsoe showed that platinous
bromide does not lose weight at 100°, but if heated at 200° for a long time a small
proportion is decomposed, and if heated for a short time at 240° no decomposition
can be detected. The salt is insoluble in water ; it forms a brownish-red soln. with
bromine water ; and a yellow liquid with a soln. of potassium bromide. J. Thomsen
gave (Pt, O, 4HBr, Aq.)=43*44 CaIs. for the heat of formation of hydrobromoplatinous
acid, H2PtBr4. W. Manchot and G. Lchmann observed that the halogen
is eliminated more quickly in a current of carbon monoxide better than it is in an
indifferent gas, and no carbonyl bromide is formed. W. Rosenheim and W. Levy
described a complex with phosphorous bromide, namely, platinous dibromobisphosphorotribromide,
[Pt(PBr3) 2Br2] ; and also platinous dibromophosphorotribromide,
[Pt(PBr3)Br2J2.
J. Reiset obtained platinous tetramminobromide* [Pt(NH3)4]Br2.nH20, by
the action of barium bromide on a soln. of the tetramminosulphate. The cubic;
crystals are not decomposed by boiling water ; and P. T. Cleve added that if the
mixed soln. is evaporated over sulphuric acid, and the crystals are pressed between
bibulous paper, four-sided prisms or plates of the hemitrihydrate are formed. The
crystals effloresce in dry air ; they lose water at 100° ; and they dissolve freely in
water. C. Nogareda, and A. A. Grinberg and B. V. Ptitsin studied the thermal
decomposition, and formation of the bromide from its elements. E. Biilmann and
A. C. Anderson prepared green platinous tetramniinobromoplatinate, [Pt(NH3)4J-
PtBr4, sparingly soluble in -water ; and they also obtained a complex platinous allylalcoholtetramminobromoplatinite,
[Pt(NHg)4][Pt(C3H5OH) Br3]2. L. A. Tschugaeff
and 1.1. Tscherniaeff prepared platinous aquotriamminobromoplatinite, [Pt(NH3J3-
(H2O)]PtBr4, by adding potassium bromoplatinite to a soln. of the chloride.
The green needles are converted by hydrobromic acid or a soluble bromide into
platinous bromotriamminobromoplatinite, [Pt(NHg)3BrJ2PtBr4. L. A. Tschugaefi
prepared this salt by the method employed for the corresponding chloro-salt.
P. T. Cleve prepared platinous trans-dibromodiammine, [Pt(NH3)2Br2], by the
action of potassium bromide on the corresponding chloride, and drying the product
at 100°. The pale yellow, crystalline powder is sparingly soluble in hot water, and
the soln. on cooling deposits the original salt ; he also obtained in an analogous
manner, platinous Cis-dibromodiammine in golden-yellow needles. H. D. K. Drew
and co-workers prepared the three isomerides of platinous dibromodiammine,
[Pt(NHg)2Br2], analogous with the corresponding chlorides (q.v.), by the action
of an excess of a soln. of alkali bromide on the corresponding chloride, or of hydrobromic
acid on the corresponding base. The a-salt forms sulphur-yellow, prismatic
needles, which give no coloration with phenoxtellurine dibisulphate ; a fS-salt
forms orange needles which give an orange -y el low coloration with phenoxtellurine
dibisulphate ; and tihey-salt occurs in clusters of dark orange prisms. H. Alexander
prepared platinous tetrahydroxylaniinebroniide, [Pt(NH2OH)4]Br2, in colourless
needles, by the action of hydrobromic acid on the corresponding chloride.