Separation of Titanium from Rare Earths, Beryllium ... - ACS Publications

May 1, 2002 - Cation Exchange Separation of Molybdenum, Tungsten, Niobium, and Tantalum from Other Metal Ions. J. S. Fritz and L. H. Dahmer. Analytica...
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it can be applied to lithium. Table VI lists a series of replicEke determinations to indicate the reproducibility of the method when applied GO lithium. ACKNOWLEDGMENT

The authors are indebted to K. J. Kelly of this laboratcry without whose unceasing interest in the problem of determining oxygen in lithium this work would never have been completed. Iliscussions of the problems with J. C. White of Oak Ridge, with D. D. Williams of S a v a l Research Lab, and with Hyman Kirtchik of General Electric have been most helpfL1.

(9) Turovtseva, Z. >I., Litvinova, N. F.,

LITERATURE CITED

( 1 ) Bate, L. C., Leddicotte, G.

W.,U. S.

Atomic Energy Comm. Rept. ORNL-

2453 (1958). (2) Eberle, A. R., Lerner, M. W., Petretic, G. J., ANAL.CHEM.27, 1431 (1955). (3) Gpldberg, G., Zbid., 34, 1343 (1962). (4) Kirtchik, .Hyman, Riedman, George, U S.Atomic Energy Comm. Rept. DM62-124 (1962). ( 5 ) Meyer, A. S., Boyd, C. M., .&SAL. CHEM.31, 215 (1959). ( 6 ) Pepkowitz, L. P., Judd, W. C., Ibid., 22, 1283 (1950). ( 7 ) Potts, J. R., Hobart, E. W., U. S.

Atomic Energy Comm. Rept. TID7606, p. 120 (1960). (8) Sax, N. I., Steinmetz, H., U. S.Atomic Energy Comm. Rept. ORNL-2570 (1958).

Proc. U . N. Intern. Conf. Peaceful Uses At. Energy, 2nd Geneva, 1958 28, 593. (10) White, J. C., Oak Ridge National Laboratory, Oak Ridge, Tenn., private communication (1958). (11) White, J. C., Ross, W. J., Rowan, R., ANAL.CHEM.26, 210 (1954). (12) Williams, D. D., Naval Research Laboratory, Washington, D. C., private communication (1962).

RECEIVED for review Yovember 13, 1962. Accepted May 23, 1963. Work performed under U. S. Atomic Energy Commission Contract AT(30-1)2789. Presented at the Sixth.Conference on Analytical Chemistry in Nuclear Reactor Technology, Gatlinburg, Tenn., October 11. 1962.

Separation of Titanium from Rare Earths, Beryllium, Niobium, Iron, Aluminum, Thorium, Magnesium, Manganese, and Other Elements by Cation Exchange Chromatography F. W. E. STRELOW National Chemical Research laborafory, Soufh African Council for Scientific and Industrial Research, Pretoria, South Africa

b A systematic study o f the absorbabilities o f cations with A G 50W-X8 resin in sulfuric acid indicates that the difference in the equilibrium distribution coefficients o f titanium(lV) and a considerable number o f other ions i s large enough for a good separation. This fact was applied t o develop a cation exchange chromatographic procedure for the separation of titanium from Fe(lll), AI(III), Be(ll), Sc(lll), Y(III), La(lll), Th(lV], Mg(ll), Mn(ll), Co(ll), Cu(ll), Ni(ll), Zn(ll), and Cd(ll). Titanium i s eluted with 1 N HzS04 containing 1% of Hz02 as stabilizing agent to suppress hydrolysis, while the other ions stay on the column. Ions such as Ga(lll), Fe(ll), Hg(ll), Hg(l), TI(I), Ag(l), and &(I) remain on the column as well. Nb(V), V(V), Mo(VI), Ta(V), and W(VI) can b e eluted from the column with 0.5h H2S04 containing 1 H202 before the separation of titanium from the more strongly a b sorbed elements i s started. Ta(V) and W(VI), however tend t o interfere b y hydrolysis. Zr(l\l) and U(VI) accompany titanium. The separations a r e satisfactory wheii up to 5 meq. o f beryllium or 10 meq. o f the other ions are present with titanium. Titanium can b e quantitatively sepaiated from any o f the separated ions in proportions from 1 : l o 0 to 1OO:l and total amounts of 10 meq. and often more. In many cases, coissiderably higher ratios can b e separated with good results.

T

ion exchange separation of titanium from various other elements has received considerable attention during the last decade. Some published cation and anion exchange separation procedures are summarized in Tables I and 11. Many of the procedures use eluting agents containing fluoride or organic reagents. For this reason they often are less attractive when further separations or determinations have to be conducted on the eluates. Furthermore, most of these methods separate titanium from a relatively small number of other elements. A method using an eluent which does not unduly complicate further separation., HE

Table I.

yo

Resin Uonex 50

Cation Exchange Procedures for Separation o f Titanium

Elements separated Zr, Th

Zr KU-2 Sulfonated polystyrene h 1 KU-2 -11 -1G 50 Zr XU-2 Fe SBS Fe Cr SBS KU- 1 lln ;imberlite IR-120H II(IV)

SBS

SBS

and will separate titanium from a fairly large number of elements, would have some advantage. Alimarin (4-6) advocated the use of sulfuric or hydrochloric acid plus hydrogen peroxide as eluting agent for the separation of Xb(V), V(V), and hIo(V1) from Ti(1V) using a Russian cation exchange resin, and Ryabchikov (20) separated tungsten from titanium on a cation exchange column using sulfuric acidhydrogen peroxide mixtures. Fritz ( l a ) separated vanadium from titanium and a number of other elements on a column of Dowex 50W-X8 resin by eluting vanadium with 0.01M H2S04or HClO4 containing 1% H1O?. Titanium is con-

T.', Mo,

Citric acid for Zr, Ti, ammonium citrate for Th I S RCI for Ti: 3N HC1 for Zr EDTA-HzO? niixtures 0 75'2' HCl for Ti 2'2' HC1 for 11 2 4 HCI for TI, 5 5 HC1 for Zr 0 25A' HC1 for Ti 4 S HC1 for Fe 0 4 5 HC1 for Ti 4 t HC1 for Fe EDTA HC1 solutions 0 5 S HC1 for 1\lnO4-: LV HC1 for Ti 2'2' HC1 for Ti: 2 S HgSO, for U(IV) H2S04of pH 5 Hi01 fo; IT7: 3 . 5 s

Ref. (10)

+

lT

SBS Nb Nb KU-2 Sulfonated polystyrene Fe

Eluent

m-

+ +

H&O, for Ti H ~ S07~ p~ ) ~I H>O*for I-, MO, 0 3V HnSO, 5% citric acid for Nb 0 3 5 HC1 H202 for Xb ZV KCN for Fe. 3 5-YH1SO4 for T1

+ +

VOL. 35, NO. 9 , AUGUST 1963

1279

t o 20 em. long. Flow rates were 3.5 =t 0.5 ml. per minute. ;inalytical reagent quality chemicals were used whenever possible. Standard solutions containing about 5 meq. of the ion per 20 nil. in dilute sulfuric acid were prepared and standardized by a triplicate determination using an appropriate analytical method. Titanium solutions of this concentration were unstable a t the concentration of free acid employed (1S). They were stabilized by the addition of H202. Kiobiuni and tantalum were kept in a solution containing a small excess of free KOH and acidified shortly before they were put onto the column. The hydrogen peroxide was Perhydrol, 307, w., 11.

HLh.

mi

E.

Procedure. Composite elution curveq for various cation pairs nertt prepared using a 20-gram resin coluniii as described above, about 5 meq. of the cation, and 1.Y H2SOI containing 1% of hydrogen peroxide as eluent. Twenty-five-milliliter aliquots of the eluate were collected using an automatic fraction collector and the amounts of the elements in the aliquots were determined by an appropriate analytical procedure (Table 111). The elution curves for Ti(1V) He(1I) and Ti(1V) - SIg(I1) are prew i t e d in Figure 1. The curves for Zn(II), Cd(II), Cu(II), Co(II), and Si(I1) are very similar to the c u r m for SIg(I1) giien in Figure 1. SIangane*e(lI) appears in the eluate nhen 700 nil. of the eluent ha1 e been passed through the column. So Fe(III), T h (IY), .il(III), dc(III), 17(III). La(III), Ce(III), Yb(III), or Ga(II1) is eluted in the f i r 4 TOO i d . In 0.5S H2P04,the equilibrium disti ihutioii cocffiriPnt for Ti(1V) is about 45, Thi. wggeits that the elution of titanium n ill he considerably retarded v hen 0.5Y H2SOr containing HJO? i> uyed a- eluent. S h ( Y ) , V(Y), and lIo(T'1) in 0.5-Y H2S01 containing Hs02 haT-e didribution coefficient. smallpr than 5 . Therefore, it h o u l d he possilile to .elmrate theqe element; from titaniinii u-ing 0.5Y HZ901 containing

I'Ti

Figure 1 . Experimental elution curves for titanium-beryllium and titaniummagnesium A b o u t 5 meq. of each present

w i i t i w l y c3luted with 1.Y acid containing 1 e4 H?O? and thus separated from ferric iron \I-hich ataj-q on the colun1n. .sy+wiatie st'udy (23) of t'iie equilibrium diqtribution coefficients of cations in sulfuric acid media suggests that the foregoing method. can be modified and extended to make possible the aeparation of titanium from more than 20 cations. .itlout 1 S sulfuric acid containing hydrogen lieroride is the m o d favorable eluting agent for the separation of titanium froni most di-, tri-, and higher valent cations when -iG 5OW-X8 Bio-Rad or an equivalent cation exchange resin i, used. EXPERIMENTAL

Apparatus, Reagents, a n d Solutions.

Horosilicate glais tubes 50 em. long and 1.9 cni. in diameter with a fusedin glass .;inter of S o . 2 porosity and a buret t a p a t the bottom were used as columns. The columns were fitted with 500-ml. dropping funnels connected hy ground-glass joints. T h e 1280

ANALYTiCAI CHEMISTRY

column, were loaded with 20.0 _t 0.1 grams (oT-rn-tlry weight) of I3io-Rad -4G 50K-X8 re& of 100- to 200-meJ1 particle qiae, in the hydrogen foim. The pretrratment of the resin and the column Iirqiaration ha! P been d r w i h d (21). The resulting resin bed naq 19

Table

II.

Resin

Anion Exchange Procedures for Separation o f Titanium Elemrnt,e

sepnrated

1)ou ('1 1

I., I-c

.4inl,erlite 11iA-4OO

Fe, Cr, Si,:ind

Doa-ex 1 .kmberlite IRA-400

110,IT, S b Fe. Cr. Si. \-. hlo. Co, RIn, W,Sb, Ta S b , Ta I-,110,Zr

EDC-101'

Donex 1 Ilowex 1 Domx 1

Zr, Nb, Ta S b , Ta, W,310, %r

Hilent

1 2 5 HC1 for V : 9>\-HC1 for Ti; 1.Y HC1 for Fe

.Iscorbate solutions

HC1

o

+

(14) (7)

-HHmF,mixtures + lor; S ~ Ffor V,

ill) (16)

+ H F + SH4C1 mixtures + HC1 + HlO? mix-

(16)

hIo, Ti

He1

(19) (16)

0 I.\- H,SO? H?O?for Ti HC1 H F mixtures HC1 H F mixtures for other ions: 3.Y HC1 for Ti

++

Ref.

Zr. 0 layH?SP4

Oxalic acid

tures

+ H?O, for

(8)

H202 as eluent. The higher acid concentration compared rvith that used by Fritz (12) nil1 be falorable when larger amounts of titanium are prezent, because titanium tend: to hydrolyze a t low sulfuric acid concentrations even in the presence of hydrog,en peroxide. Composite elution rurves for Ti(I1‘jS b ( V ) and Ti(IT’)-\Io(VI) are pre.ented in Figure 2 . The elution curve for V(V) is almost fimilar to that of 1\Io(T’I), but the V(Tr) peak appears a little later in the eluate than the 1\10 (VI) peak. Since h b ( V ) , V(V), and lIo(V1) are only verj weaklv or not a t all absorbed, the fra:tions for the esiierimental elution c x v e i were taken from the beginning of the ab-orption step Analysis of Syr thetic Samples. As a result of the foregoing work, a neth hod for t h e separation of titanium w t s elaborated and applied t o t h e analysis of synthetic solution.. . prepared b y measuring out and mixing amounts of stand2 rdized iolutions of titanium a n d v a r i m s cations. The cations were a3sorbed on a resin bed 19 to 20 cm. long and 1.9 em. in diameter from a solution not more than 0 3 5 in free acid. Titanium a a s cluted with 350 nil. of 112’ HzS04containing 1% of H,O? The sulfuric acid was rt’mo1 ed from thcb column by washing 151th 100 ml. of 0 1-2’ HCI, and the other cations nere then eluted with h j drochloric acid of %mountsand concentrations a$ liited in Table IV. The amount. of the different cation< in the eluate- were determined by appropriate analytical procedures (Table 111) The I w i l t s of the deterniinations are i r e wnted in Table V. V(V) and Rlo(T’I), ithen present, were c,luted with 250 nil of 0 . 5 s H,SO4 containing 1% H2C12. For niobium, 360 ml. of the same eluent mas used. Sulfuric acid waq nashed out of the column n i t h 100 ml. of 0.1S HC1. The titanium was then elited with 250 i d . of 2 5 HCl. Because Kb(V), V(V), :nid lIo(V1) pass directly through the column, the eluate v a s collwted from the beginning of the ahiorption -tep. DISCUSSION

Thc de3cribed mrthod pro\ ides a ~ i m p l emeans for qeparating titanium quantitatively from Fe(III), Fe(II), All(III). Be(II), Sc(III), T ( I I I ) , La (111) and the rare earths, Th(IT’j, G a ( I I I ) , 1\Ig(II), lIIl(II), Co(II), cu (II), S i ( I I ) , Zn(II), and Cd(I1). S o t much more than 5 ineq. of beryllium can be qeparated from 5 01 N en 10 nieq. of titanium u h g a c201umn of the described a e . HoneT.er, 10 meq. of aluminum, ferric i r o i , and the other ions named above van be separated from 10 meq. of titanium. Furthermore, titanium can be quantitatively separated from any of these ions in equivalent proportioil- from 1 :IO0 t o

Table 111.

Cation Ti(1V) Fe( I11j Al( 111;

La(III), Y(III), Sc(111) Be Cu(I1j hln(I1j hIg(II), Zn(II), Cd(I1) X(11) Co(I1) Th(1Vj Sb(V) T-( \- I

lIo(V1)

Analytical Methods Used

Method Gravimetrically as Ti02 after precipitation with ammonia or a4 oxinate TiO( CgH60,N)*;colorimetrically as HnO?-coniplex or tiron complex (elution curves) By dichromate titration after reduction with silver reductor colorimetrically as Fe( 11)-o-phenanthroline complex Gravimetrirally as A 1 2 0 3 after precipitation with ammonia or as oxinate A1( CgH60N)8;colorimetrically as alizarin red S complex in presence of calcium Gravimetrically as oxides after precipitation with oxalic. (rid Gravimetrically as oxide after precipitation with amnionin, colorimetrically with Chrome azurol-S Thiosulfate titration of iodine liberated from potassium iodide, colorimetrically xith rubeanic acid Gravimetrically as MnpP?Oi: colorimetrically as l I n 0 4 - after periodate oxidation Titration with EDTA using Eriochrome Black T as indicator Gravimetrically as dimethylglyoxime complex; colorimetrically as dimethylglyoxime complex after bromine oxidation (CNS)?: colorimetrically as Gravimetrically as [Co(C6HjN)4] nitroso R salt complex Gravimetrically as Tho? after precipitation with oxalic avid: colorimetrically nith thorin Gravimetricallv as Nbd.35 after precipitation with tannic acid : colorimetrically as thiocyanatk complex in acetone Titration with ferrous iron using diphenyl amine as indicator; colorimetrically as HaOl-complex Gravimetrically as oxinate 31002 ( C9HaON)2 : colorimetrically as thiocyanate complex

1oO:l easily. Considerably higher raTable IV, Eluents Used for Different tios can often be beparated with good Cations results. Calcium can be separated Eluent ___-__ when concentrations are low enough to HC1 prevent sulfate precipitation. Lead, Cation 111. normality strontium, and barium interfere beFt.(III), Be(II), cause they form insoluble sulfates. m d I I ) , Cu(II), 40[) 2 \Sb(T’), V(V),and Mo(V1) can be eluted 1ln(II), %n(II),> T i ( I I ) , Co(I1) J n i t h 0.5N HzS04 containing H301 before the titanium is eluted, and can thus,)); : ;(: ; ~(IIIj, 400 3\ be separated. Vanadium should be in ~~(111) 500 4 \the fire-valent state because the preyCd(I1) 200 1.\ ence of substantial amounts of fourTh(I\-) Resin xshed

Table V.

Ti 55.1 6 . ,j1

0

55

110.2 55.1 220.4 0.55 55.1 0.55 351 . O 5 i.1 56.4 .i6 4 56 4 36 4 66 4 112 9 0 56 56 4 56 4 56 4 56 4 56 4 56 4 56 4 56 4

Results of Quantitative Separations of Synthetic Mixtures of Cations

Taken, mg. Other Fe(II1) 84 2 Fe(II1j 168 4 Fe(II1) 168 4 Fe(II1) 0 12 AI( I11j 44 7 &41(111) 2 25 AI( I I I ) 89 4La( I11 221 8 I&(111) 413 6 La(II1I 5 5 YIIII 1 146 T Sc.(III) 79 6 BelII) 21 8 ~M g ( 11) Cu( 11) >In(11) ?\In(11) P*ln(II) Zn(I1) Cd( 11) Xi(I1) COiII) Th( IT’) Tb(T7)

v0-1

60 156 151 0 302 153 246 131

1

9 1 38 8

7

2 7 i2I 3 283 8 118 7 124 5 189 6

Found, nig.

Ti 55 5 0 110

2 i0 1 48 i 0 09 54 i 0.01 4 f0 2 .i. 1i i n 1 220 2 i 0 4 0 55 f 0 01 55.0 i 0 . 1 0.54 f 0.01 551 3 f O . i L5.2 i 0 . 2 56.3 f 0 . 2 56.5 f 0 . 1 56 1 f 0 . 1 j6.4 i0.2 .i6.3 i 0 . 2 56.3 i 0 . 2 0 56 f 0 01 563 = t o 1 36 4 3~ 0 1 563 1 0 2 ,56 5 f 0 1 56.4 f 0 . 1 56.4 f 0 . 2 56.5 f 0 . 2 56.5 i 0 . 1

0t h

e

r

84.3 f 0 1 168 3 f 0 2 16S.4 f 0 . 3 0 43 i 0 01 448 1 0 1 2 22 10 03 8Y .ii 0 2 221 7 i 0 2 443 8 f 0 3 5 4 f 0 1 1468 i 0 2 i 9 5 f0 2 24s 1 0 1 600 1 0 1 156 8 10 2 151 6 1 0 3 0 38 i 0 01 246 3 134 6 121 d 284 0 118.9 124 6 189 9

10 4 i0 1 10 3 i0 2 i 0.4 i0 2 & u 5

3Io(T’I) Results are means of triplicate determinations with calculated standard deviation?

VOL. 35, NO. 9, AUGUST 1963

1281

valent vanadium leads to serious bubble formation which may disturb the resin bed. W(V1) behaves like Nb(V) and can be separated. However, the separation is not always reliable because it tends to hydrolyze. Tantalum interferes because its tendency to hydrolyze is much stronger. Ryabchikor (20) separated tungsten by eluting it with H2S04-(NHd) 2SO4-Hz02 mixtures of p H 5. This procedure is not satisfactory when larger amounts of titanium are present, because, at this p H value, titanium solutions tend to hydrolyze even when fairly large amounts of HzOzare present. Divalent mercury is retained by the column when no chloride is present and can be separated. Hg(I), Tl(I), -4g (I), and Cs(1) also stay on the column when titanium is eluted and can be separated. Rb(1) and K(1) can be separated only when less than 1 meq. of these ions and no other ions besides titanium are present. Even under these circumstances the potassium is not separated very satisfactorily. With larger amounts, partial overlapping of the elution curves occurs. Xa(1). U(VI), and Zr(1V) accompany titanium through the separation process. h very satisfactory separation of titanium from zirconium using hydrochloric acid as eluent has been described (26).

-^.

iL'.

---

-

1Y -"

2 -

i

r

-

.. -

f-

I L

-

c ?

--

Ti 8.

-

~

i ~

I

I --t. l, - ^_ I

-".Lr

1 ^^.^

:Lr

-.

ACKNOWLEDGMENT About 5 meq. of titanium and 4 mmoles of niobium or 2 mmoles of molybdenum present

The author thanks R. E. E. Riedel of the Sational Chemical Research Laboratory for her valuable help in doing a considerable part of the experimental work for this publication.

( 7 ) .kthavale, V. T., Tadkarni, M. S . , Venkateswarlu, C., Anal. Chim. Acta

LITERATURE CITED

(8) Bandi, W. R., Buyok, E. G., Lexis,

23,438 (1960).

(1) Alimarin, I. P., Belyavskaya, T. A , . Bazhanova, L. .4.,Vestn. Mosk. Uniu., Ser. Mat., Mekhan., Astron., F i z . 1 Khim. 11, No. 2, 167 (1956); C.A. 51, 17585e (1957). 12) Alimarin, I. I'.! Belyavskaya, T. .i,, Bazhanova, L. -I.> Zhur. -4nal. Khit)z, 12,337 (1957); C.A. 52, 1835i(1958). (3) Alimarin, I. P., Borzenkova, S . P., T'estn. M o s k . Unio., Ser. Mat., Mekhan., Astron., F i z. i Khim. 13, KO. 6, 191 (1958); C.A. 53, 15840i (1959). (4) Alimarin, I. P., Medvedeva, A. AI,, Khromatog., ee Teoriya i Primenen., A k a d . S a u k . S.S.S.R., T r u d y V'sesoyuz. Soveshchaniya, Moscoz: 1958, 379; C . d . 55, 17360d (1961). (5) hlimarin, I. P., Medvedeva, A. Yf .! T r u d y Moskov. Inst. T o n k o l Khim. Teknol. im. 11. 1'. Lomonosova 1956, So. 6, 3; C . A . 53, 138851,(1959). ( 6 ) illimarin, I. P., hledvedeva, A . AI., Z U V O ~Lab. S ~ . 21, 1416 (1955); C.:I. 50, 8382c (1956).

1282

ANALYTICAL CHEMISTRY

L. L.. Melnick. L hI.. ANAL.CHEM 33, 1275 (1961).' (9) ?Belyavskaya, T. A,! Alimarin, I. P., holosova, I. F., Zhur. Anal. Khim. 13,668 (1958). (10) Brorrn, R7. E., Rieman, W.,111, J . 24n2.Chem. Soc. 74, 1275 (1952). (11) Chernobrov, S. M., Kolonina, N . P., Khromatog., ee Teoriya i Primenen., d k a d . iYauk. S.S.S.R., Sfoskov. 1960: C.A. 55,24384~(1961). 112) Fritz. J. S..Abbink, J. E., Ax.41.. ' CHERI.34, lOSO(1962). (13) Giuffre, L., Capiazi, F. M.,Ann. Chim. (Rorna) 49, 1834 (1959); C . d . 54, 162733' (1960). (14) Hague, J. L., Brown, E. D., Bright. H. h., J . Res. Bitr. Stand. 53, 261 (1954). (15) Hague, J. L., Machlan, L. .I., Ibid., 62, 11 (1959). (16) Korkisch, J., V i k r o c h i t t i . .4cta 1961, Yo. 2 , 262. ( 1 7 ) Korkisch, J., Z . Anal. Cheni. 178, 39 (1960).

(18) Korkisch, J., Farag, il., Mzkrochzm. Acta 1958, No. 5, 659. (19) Kraus, K. il., Nelson, F., Smith, G. W., J . Phys. Chem. 58, 11 (1954). 1201 Rvabchikov. D. I.. Bukhtiarov.V. E..

Zhu; Anal. Khim.' 15, 242 (1960); C.A. 54, 19261$(1960). (21) Strelow, F. W ,E., ANAL.CHEM.31, 1201 (1959). (22) Ibid., p. 1974. 123) Strelow. F. W. E.. unmblished data. (24) Tonosaki, K., -4tOm4 M., J . Chein. Soc. J a p a n , Pure Chem. Sect. 80, 1290 (1959). (25) Tsitovich, I. K., Zhur. Anal. k-hzm. 15, 503 (1960); C.=L. 55, 152238 (1961). 126'1 Tsitovich. I. K.. Zhur. Prikl. Khzrn. ' 34, 218 (196i); C.6. 55, 11029c (1961). ( 2 7 ) Tsyvina, B. S., Kon'kova, 0. I-., Zavodsk. Lab. 25, 403 (1959); C.A. 53, 12937a (1959). (28) Walter, R. I , J . Znorg. Sucl. Chem. 6 , 5 8 (1958). 129'1 Yoshino. T.. Koiinia. 11 . Bitll. Chem. Soc. Japan 23, 16 (1950) RECEIVEDfor review December 26, 1962. -4crepted April 22, 1963.