were obtained. The results indicate that PtBrsV2undergoes hydrolysis siniilar to that observed with PtCla-’; values i could not be obhowever, ?? tained by titration of the hydrolyzed solutions with NaOH, apparently because the hydrolysis products were not so acidic as the analogous chloro compounds. The current-potential curves obtained from hydrolyzed KzPtBr6 solutions which were made 1P in bromide displayed only the wave characteristic of PtBr6+ reduction, indicating that bromide ion rapidly converts the products of hydrolysis back into PtBrR-2. The results of potential-step currentintegration experiments with hydrolyzed PtBr6-’ and with PtBr4-’ solutions are summarized in Table IV. The nvalue for P ~ B ~ reduction C-~ is 2 only in 1F Br- solutions. I n both 1F HClO, and 1F NaC104 solutions n is 4. It is interesting (if unexplained) that PtBr4-2 gives a two-electron reduction wave in HC104 while PtC14-2 does not.
-
+ 2e-
or HClOi
The combination of thin layer electrochemical experiments described above has led to the following conclusions:
A. In 1F HC1: 1. The oxidation of PtC14-2 occurs according to HC1
+
ca. ‘/3 Pt(OH)zC14-2 ca. 2 / 3 PtC&-’ 2e-
+
-+ -+
+
2. The reduction of PtC14-2 occurs according to
+ 2e-
PtC14-’
Pt
4C1-
+
Pt(0H) ,c16- m-’ 4ePt mOH-
+ Pt
+ 4Br-
3. The reduction
of Pt(H20),Brs-,m-2 occurs according to
+
P ~ ( H ~ O ) . , B ~ ~ H ,4e~ ~ -+ ~ Pt t (6 - m)Br-
+ mHzO
LITERATURE CITED
(1)
Dreyer, R., el al., 2. Phys. Chem. 224,
199 (1963).
12) Frumkin. A. Tu’.. Trans. Faradaw Soc. 54, 1% (1958). ’ (3) Hubbard, A. T., Anson, F. C., ANAL. CHEM.38, 58 (1966). >
,
p. 1601.
-+.
+ (6 - m)C1-
PtBrs-2 f 2e-
Anson, F. C., Ibid., p. 692. (6) Kleinberg, J., ed., Inorganic Syntheses 7, 240 (1963). (7) Kravtsov, I-. I., Sinakov, B. V., Vestn. Leningr. Unit?. 19 (lo), Ser. Fiz. i Khim 2 , 90 (1964). ( 8 ) .La:imer, W. L., “Oxidation Potentials, 2nd ed., p. 207, Prentice-Hall,
New York, 1952.
(9) Langford, C. I-I., Gray, H. B., “Ligand Substitution Processes,” p. 24, W. A.
Benjamin, New York, 1965.
2. The reduction of PtBr6-2 occurs according to PtBre-’ 2ep t B 1 - 4 ~ ~ 2e-
-
+ 2e-
PtBrd-’
(5) Hubbard, 8.T., Osteryoung, R. A.,
11. PtBre-’ and PtBr4+ A. I n 1F NaBr: 1. The oxidation of PtBr4+ occurs according to
+
+ 6Br-
(4)Hubbard, 8.T., Anson, F. C., Ibid.,
3. The reduction of Pt(OH),Cle- m-2 occurs according to
PtBr4-’
I. PtC16-2 and PtC14-2
+
PtC14-2 2c13. The reduction product of Pt(OH)zC14-2and Pt(OH)4C12-2 (produced by hydrolysis of PtCle-’) is PtCla+ B. In 1F NaC10, solutions: 1. The reduction of PtC&-’ occurs according to PtC16-2 4ePt 6C1-
-+ Pt
2. The reduction of P ~ B I - occurs ~-~ according to
HC1
+
CONCLUSIONS
PtCh-’
PtCle-2
+ 4e-
PtBrs-’
2. The reduction of PtC&-’ occurs according to
+
B. In 1F T\TaC104or 1F HClOd: 1. The reduction of PtBr6-2 occurs according to
(10) Lingane, J. J., J . Electroanal. Chem. 7, 94 (1964).
RECEIVEDfor review June 24, 19G6. Accepted September 19, 1968. This work was supported in part by the U. S. Army Research Office (Durham). -4.T.I-I. held a NSF predoctoral fellowship. F.C.A. is an Alfred P. Sloan Foundation Research Fellow.
Correct ion Chemical Analysis of the Alkali Metal Tungsten Bronzes I n this article by Bruce A. Raby and Charles V. Banks [ANAL.CHEM.36, 1106 (1964)], an error appears on page 1109 column 1, Figure 4. A portion of the figure appears below. On the right side, “5,00% W” should read “5.00% Li.”
I
SAMPLE O F LITHIUM TUNGSTATE
I I
t
METHOD
F I LT RATE
5.00‘10
w
Should be. . . . . . . . ” 5 . 0 0 % ‘Li
VOL. 38, NO. 13, DECEMBER 1966 e
1883
