Feb. 20, 1958
COMMUNICATIONS TO THE EDITOR
1011
the trans complex, which is formed by the direct action of hydrogen peroxide on cobalt(I1) glycinate, and an unstable yellow-brown substance After correcting for the presence of the trans complex, the absorption spectrum of the yellow-brown material was found to be nearly identical to that of tetrakis- (glycylglycinate)-p-peroxodicobalt(111) in both visible and ultraviolet regions (no rnax. or min.). The corresponding compounds of valine and leucine can be extracted into butanol, indicating a neutral molecule. THELILLYRESEARCH LABORATORIES The formation of a peroxo complex is indicated PAVLF. WILEY ELI LILLYA N D COMPANY IXDIANAPOLIS G , INDIANA MAX V. SEAL,JR. by the evolution of oxygen from the catalase RECEIVED JANUARY 33, 1955 treated amber solutions upon the addition of potassium triiodide,7 acidification or standing. Using manometric methods the rate constant for PEROXODICOBALT(II1) COMPLEXES, the decomposition of the peroxo complex was found INTERMEDIATES IN THE CATALYTIC min.-' a t 0'. to be 9 X DECOMPOSITION OF HYDROGEN PEROXIDE The formation of a peroxo complex is also shown Sir. by the reduction of the catalase treated amber Cobalt(I1) complexes of neutral amino acids are solutions a t the dropping mercury electrode. only slowly oxidized by oxygen.' However, they Half-waves were observed a t -0.11, -0.96 and catalyze the decomposition of hydrogen peroxide -1.48 volts us. S.C.E. The first wave is due to and, a t the same time, they are rapidly oxidized to the reduction of cobalt(II1) while the second is due stable red-violet cobalt(II1) c o n i p l e x e ~ . ~We - ~ have to the reduction of liberated hydrogen peroxide. also observed the transient appearance of amber The second wave is broad and disappears as the and red solutions. The similarity of the amber amber solutions turn red. The rate constant for colors to those of solutions of peroxodicobalt(II1) the simultaneous decrease in the diffusion current complexes4 prompted this investigation of the is 7.5 X min.-l a t 0". reaction between hydrogen peroxide and the Although several reactions may be responsible cobalt(I1) complexes of the glycinate ion. for the decomposition of hydrogen peroxide by the The stable red-violet solutions contain an equi- cobalt(I1) glycinate ion, a satisfactory mechalibrium mixture of cis and tram-hydroaquobis- nism should include the formation and decom(g!ycinate)-cobalt(II1). Identical solutions are ob- position of a peroxodicobalt(II1) complex, probtained by treating chloraquobis-(g1ycinate)-cobalt- ably diaquo tetrakis- (glycinate)-p-peroxodicobalt(111) with silver oxide. These solutions were (111). The decomposition of the hydrogen peroxseparated into two fractions by means of a cation- ide soon stops because of the simultaneous forexchange resin and the two fractions were identi- mation of trans-hydroxoaquobis-(g1ycinate)-cobaltfied by comparing their absorption spectra with (111),a stable complex. The results of a more dethose of cis- and tra,ns-hydroxoaquobis-(ethylene- tailed study will be reported in a later publication. diamine)-cobalt(II1) at 0". The assignment of the Future investigations include a study of the mechacis and trans configurations is also in agreement with nisms of the formation of the peroxo complexes. traits effect on the strength of diaquo acids.6 The authors wish to thank the Fels Foundation The color of the transient red solutions is due to and the Kettering Foundation for the use of the the trans-cobalt(II1) complex which undergoes an Warburg Apparatus and Sargent Model X X I intramolecular rearrangement to form the red- Polarograph, respectively. This work was supviolet equilibrium mixtures. Spectrophotometric ported by a grant from the National Institutes of studies showed that the amber solutions contained Health (PHS).
point and X-ray diffraction pattern. Concentration of the methanol used for trituration gave a syrup which furnished the rnethylphenylhydrazone of n-talose. A sample of the 0.5 N acid hydrolysate of hygromycin B was subjected to paper chromatography using pyridine-ethyl acetate ( 2 :5 ) saturated with water as the moving phase. The only reducing sugar found to be present had an Kr value identical with that of D-talose.
(1) H. Ley a n d 11. Winkler, B e y . 42, 3S9.4 (1909); 46, 372 (1912). (2) J Hearon, 13. Rurk and A. L . Sclioole, J . N u l . Cancer I n s t . , 9,
337 (1949). (3) V. I. Avvakurnov a n d G. A. Dobren'kov, T r n d y Kaean. K h i i n . Tcrhnol. I n s f . i m S. A f . Kirova, 19-20, 229 (1054-55). (4) L. Michaelis, Fedevofion Proc., 7, 509 (1948). (5) J. Rjerrum a n d L. Rasmussen, Acta Chenr. Scand., 6, 1265 (1952).
DEPARTMENT OF CHEMISTRY AKTIOCHCOLLEGE YELLOW SPRINGS, OHIO
R I C H A R D (3. YALMAN MARGARET B. WARGA RECEIVED DECEMBER 7, 1957
(6) C. Tanford, D. C. Kirk, J r , , and M. K. Chantoont, Jr., '76, 5325 (1954). (7) R. G. Yalman. A n a l . Chem., 28, 01 (1956).
JOURNAL,
THfS
