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Radiochemical studies of cobalt carbonyl hydride derivatives Day, Alison E. 1950

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L'lS- 3 6f RADIOCHEMICAL STUDIES of COBALT CARBONYL HYDRIDE DERIVATIVES. by A l i s o n E» Day Submitted i n p a r t i a l f u l f i l m e n t of the requirements for the degree of Master of Arts . The University o f ' B r i t i s h Columbia Vancouver, B.C. A p r i l , 1950. d ^ ^ k y . ^ My 2 >9s* ABSTRACT. 1. The compound [?°(C0)^J 2 1 CoCphth^ j was prepared by a previously described method (15). It was found to be unstable In the dry state and In s o l  ution i n various organic solvents. 2. The s o l u b i l i t y of the compound In various organic compounds was determined. 3. Conductance measurements i n benzaldehyde and aceto- phenone were made. The molar conductances obtained indicate that the compound is a true s a l t . 4» Transference measurements were made i n an acetone solution. The concentrations were determined by making one or other of the cobalt atoms active. The res u l t s obtained are probably i n v a l i d because of exchange between the two cobalt atoms. 5. Exchange between the two cobalt atoms i n |Tco(CO)^ j^ - £co(phth)3j was studied, and no exchange was found under the eonditions of the experiment. 6. The exchange between active, cobalt (11) ions and the cobalt phenanthrolene complex ion was studied. The exchange was found to be very rapid, reaching an equilibrium i n a few minutes. 7. The exchange between active, cobalt metal and d i - cobalt octacarbonyl was studied, no exchange being found. ACKNOWLEDGEMENT. I would l i k e to thank Dr. J. G. Hooley, without whose able assistance t h i s work would have never been completed. I would also l i k e to express my thanks to the National Research Council of Canada whose f i n a n c i a l assistance enabled work on this project to be carr i e d on during the summer of 19-48. TABLE of CONTENTS Abstract. I. H i s t o r i c a l Introduction 1 Methods of Preparation of \Co(GO) and Co(CO)^H 4 Properties of ^0(00)4] 2 and Co(CO)^H.... 9 Reactions of [po 'fcoj^g a n d Co(GO)^H 10 Structure of Metal Carbonyls 14 I I * Introduction. 19 I I I * Experimental 20 Preparation of Dicobalt Octacarbonyl..... 21 Preparation of {Co (00)^2 [cotphthJ^J 23 S o l u b i l i t y of \GO(GO)JJ2(bo(ph.th)3"]. 25 Conductance of jCofCO)^^ (pofphth)^ i n Benzaldehyde and Acetophenone....... • 27 Transference Measurements.. 31 Study of Exchange Between the Two Cobalt Atoms i n [00(00)4] 2 f G o < P h t h ) • 3 9 Study of the Exchange between Co and Co(phth)^ +. 40 Study of the Exchange between Cobalt Metal and Dicobalt Octacarbonyl..... 48 IV* Discussion of Results. 49 V. Suggestions for Further Work 52 VI. Bibliography................ 53 (1) I . HISTORICAL INTRODUCTION Carbonyl chemistry began i n 1890 with the discovery by LudwigMond of ni c k e l carbonyl, Ni(CO),. Since t h i s 4 time many metallic carbonyls and a l l i e d compounds have been discovered, and t h e i r physical and chemical properties extensively studied. The covalent metallic carbonyls so f a r known are r e s t r i c t e d to the elements of the t r a n s i t i o n groups V i a , V i l a , V i l l a , b, c, a nd lb of the periodic table. Some of these elements also form carbonyl hydrides, containing one or more atoms of hydrogen, and carbonyl n i t r o s y l s i n which one or more of the CO molecules are replaced by NO. The carbonyls, carbonyl hydrides, and n i t r o s y l carbonyls so far known arB shown i n Table I. The metal carbonyls d i f f e r i n t h e i r physical prop e r t i e s from a l l other compounds formed by the t r a n s i t i o n elements. A l l of the monomeric carbonyls are extremely v o l a t i l e , and most of the polymeric carbonyls can be sublimed. This v o l a t i l i t y connotes lack of cohesion be tween the molecules, caused by lack of external f i e l d . A closed electronic structure i s indicated by the fact that a l l of the simple carbonyls and th e i r s u b s t i t u t i o n products are dimagnetic. The carbonyls and carbonyl hydrides are soluble In non polar organic solvents, and insoluble i n polar solvents. The carbonyl hydrides are extremely v o l a t i l e substances, e x i s t i n g normally only at temperatures w e l l (2) below room temperature. Above t h i s temperature they spont aneously decompose into the carbonyl, with the evolution of hydrogen. They are weakly a c i d i c i n nature and w i l l form s a l t s with the a l k a l i metals and bulky amine cations. The present work entailed the preparation and a study of some of the properties of cobalt carbonyl hydride, Co(CO)^H, dicobalt octacarbonyl, C c o ( C 0 ) ^ ] 2 , and a s a l t phth-o-phenanthroline, using radioactive Co as a tracer. of cobalt carbonyl 60 Group Via V i l a V i l l a VHIb VIIIc lb M(C0) 6 Cr, Mo, W. r [M(CO) 5J 2 M(CO) 5 Re Pe, Ru, Os. Carbonyls M 2(C0) 9 Pe, Ru, Os. [M(CO) 4] 3 [M(COH12 M(CO) 4 Pe, Ru. Co,Rh,Ir. Ni. [M(CO) 3J X [M(CO) 3] 4 Pe. Co,Rh,Ir. M 4(CO) I : L Rh. ^ ( c o ) 3 ] ; , Cu. Carbonyl M(CO)5H M(C0) 4H 2 M(C0)^H Hydrides Re? Fe,Ru?,Os. Co,Rh?,Ir?. 1 N i t r o s y l M(C0) 2(N0) 2 M(CO)3NO 1 Carbonyls. Pe Co U) Methods of Preparation of CCo(CO)/~U and Co(CO)/H. ' ''t ti ' '•* ( 1 ) . High Pressure Synthesis. The o r i g i n a l and usually the simplest method of formation of the carbonyls i s by the d i r e c t i n t e r a c t i o n of the metal with carbon monoxide. The metal must be i n a f i n e l y divided state, and the reaction i s usually c a r r i e d out under high pressure and temperature. The techniques of t h i s method have been greatly improved by Heiber and cu his co-workers ( 1 ), who used a r o t a t i n g autoclave capable of withstanding pressures up to 350 At. Dicobalt octacarbonyl was f i r s t prepared i n t h i s manner by Mond and Hirtz (2), by passing carbon monoxide over pure cobalt at 30-250 At. and 150-220 °C. This method i s somewhat inconvenient however, as the metal must be i n a c a r e f u l l y reduced, f i n e l y divided state. In 1939 It was found by Schulten (3) that dicobalt octacarbonyl could conveniently be produced from anhydrous cobalt halides i n Hieber's autoclave. CoF 2 l s without reaction, whereas the other halides increase i n r e a c t i v i t y In the order CoCl 2< CoBr 2 <CoI 2 (1) (A) The reaction preceeds according to the equation 2CoX2+-ACu -r-800—* Co2(C0)g+• 4CuX the Cu coming from the autoclave l i n i n g . During the reac t i o n no carbonylhalide (COX)2 was formed, so the reaction did not seem to occur through the reduction of the halide (5) t o t h e m e t a l b y c a r b o n m o n o x i d e . O n t h e o t h e r h a n d , c o b a l t i o d i d e w a s s h o w n t o r e a c t w i t h c a r b o n m o n o x i d e e v e n a t r o o m t e m p e r a t u r e g i v i n g a n a d d i t i o n c o m p o u n d , C o I 2 C 0 w h i c h i s a p p r e c i a b l y v o l a t i l e . T h i s i s b e l i e v e d t o r e a c t a t t h e a n d t h e c o p p e r h a l i d e . T h e p r e s e n c e o f c o p p e r o r s i l v e r t o a c t a s h a l o g e n a c c e p t o r i s e s s e n t i a l t o t h e p r o c e s s , a n d i t h a s b e e n f o u n d t h a t t h e a d m i x t u r e o f t h e f i n e l y d i v i d e d m e t a l s t o t h e c o b a l t h a l i d e i n c r e a s e d t h e y i e l d . C o b a l t s u l p h i d e (1) w h e n t r e a t e d w i t h c a r b o n m o n o x i d e a t 2 0 0 A t . a n d 2 0 0 ° C . w i l l a l s o p r o d u c e t h e c a r b o n y l a c c o r  d i n g t o t h e e q u a t i o n I n g e n e r a l i t h a s b e e n f o u n d t h a t c a r b o n y l s c a n b e f o r m e d by t h e c o m p o u n d s o f i r o n , c o b a l t a n d n i c k e l w i t h highly p o l a r i z a b l e n o n - m e t a l s , i . e . f r o m s o l i d e s i n w h i c h the l a t t i c e f o r c e s a r e n o t o f p u r e l y i o n i c t y p e . C o b a l t c a r b o n y l h y d r i d e h a s b e e n s h o w n t o b e f o r m e d (1) in the h i g h p r e s s u r e s y n t h e s i s w h e n e v e r t h e r e a c t a n t s c o n t a i n t r a c e s o f m o i s t u r e . P a r t i a l c o n v e r s i o n i n t o t h e h y d r i d e a l s o o c c u r s w h e n m e t a l l i c c o b a l t o r c o b a l t s u l p h i d e is heated in h y d r o g e n ( 5 0 A t . ) a n d c a r b o n m o n o x i d e . c o p p e r o r s i l v e r w a l l s o f t h e v e s s e l t o f o r m 2 C 0 S + - 4 C u + 8 C 0 > > L C o ( C 0 ) / [ 2 + 2 C u 2 S 2 C o -e 8 C 0 + H 2 — » 2 C o ( C 0 - ) ^ H 2 C o S + 8 0 0 - v H 5 4 -4CU — > 2 C o ( C 0 ) , H * 2 C u P S (6) (2) Preparation i n Solution* Carbonyls can be prepared by a number of reactions' i n solution In which the reduction of the metal i s brought about by sulphides, cyanides, or even carbon monoxide I t s e l f i n strongly alkaline solution. In 1926 Job and his co-workers (5) observed that the reaction between carbon monoxide and the Grignard reagent was accelerated by the presence of s a l t s of the t r a n s i t i o n metals, and from the reaction mixture they separated an ether soluble compound of chromium which was proven to be chromium hexacarbonyl. The mechanism of the reaction appears to be the p a r t i a l reduction of the metal s a l t , and the combination of carbon monoxide with one of the reduction products, which upon acid decomposition y i e l d s , among other products, the metal carbonyl. The product by th i s method i s very pure, and i t has proved to be the best method for preparing chromium hexacarbonyl. Alkaline solutions of cobalt and nickel s a l t s absorb carbon monoxide i n the presence of cysteine, a sulphide, cyanide, t a r t r a t e , or amino acid, which on a c i d i f i c a t i o n give Ni(C0)4 and Co(C0)^H resp e c t i v e l y . Cysteine, SH.CH2.CH(WH2)C02H^(H2SR), forms with bi v  alent cobalt a complex s a l t of the type which In alkaline solution i s sensitive to oxygen and also (?) absorbs one molecule of carbon monoxide per atom of c o b a l t (6), The complex undergoes d i s p r o p o r t i o n a t i o n , The c y s t e i n e b e i n g r e c o v e r e d i n the form of a c o b a l t ( I I I ) complex, K3 [Co(SR)3] . 3 H 2 0 , and c o b a l t c a r b o n y l hydride b e i n g formed. - ..3 • 9iGo(SR) 2j-^8G0 + 2 H 2 0 — » 6 C o ( S R ) 3 y- Co(0H) 2-r-20o(C0)^H The c y s t e i n e i s thus regenerated so t h a t a small amount s u f f i c e s to b r i n g about n e a r l y complete c o n v e r s i o n of the c o b a l t s a l t (7). Analogous r e a c t i o n s take place w i t h c o b a l t (II) s a l t s and other t h i o compounds t h a t form i n n e r complex s a l t s (8). A b s o r p t i o n of carbon monoxide f i r s t forms a s u b s t i t u t e d c o b a l t c a r b o n y l d e r i v a t i v e (9) which f u r n i s h e s c o b a l t c a r b o n y l hydride when decomposed w i t h a c i d . Thus w i t h potassium xanthate, KX A (X A*CoH^.O.CS.S~) 6CoCl 2+ 12KX A+ 5C0 +EtOH *12KC1+ 4 C o X A 3 + Co 2(CO) 5.EtOH Co 2(CO) 5.EtOH + 2H +—VEtOH + Co" + CO -f |H 2 •+ Co(CO)^H An a l k a l i n e suspension of a c o b a l t s a l t i n the p r e s  ence of cyanide w i l l absorb carbon monoxide, the cyanide a g a i n a c t i n g as a c a r r i e r . T h i s method has been developed by Blanchard and Gilmont as a means of producing [00(00)4] 2 (10) (11)• The potassium s a l t of c o b a l t c a r b o n y l hydride i s formed, which upon a c i d i f i c a t i o n y i e l d s the f r e e h y d r i d e . T h i s decomposes at room temperature or on g e n t l e warming to give d i c o b a l t o c t a c a r b o n y l and hydrogen. The r e a c t i o n s i n v o l v e d are? as f o l l o w s : ( 3 ) 2Co(N03),2^- 12KCN-*2K^Go(CN)6 -»-4KN03 12K0H + 2K4Co (CN) 6 11C0 —^3K2CO3 + 12KCN + 6H20 •+ 2KCo (C0) ^  2Co(N03)2-r-12K0H -VllCO—HKNO3 + 3K2COj + 6H20 "t~KCo (CO) ^  KCo(C0)4-»-H-*—iCo(CO)^H+K + 2Co(C0) 4H—i£co(CO ) 4 7 2 +H 2 (9) Properties of [ C o ( C 0 ) ^ 2 and Co(GO)^H Dicobalt octacarbonyl usually exists as a dark brown microcrystalline s o l i d , but when pure It i s obtained as yellow c r y s t a l s . If i t stands i n a vacuum i t slowly sub limes, forming a few clear orange cr y s t a l s on the walls. Cryoscopic molecular weight determinations i n benzene and Fe(CO)(j (9) indicate the dimeric formula. It has a vapour pressure of 0.07mm. at 15*C. and melts at 51*0., decomposing at s l i g h t l y above t h i s temperature into t e t r a - cobalt dodecacarbonyl £co(C0)oJ^, and carbon monoxide. Further heating produces the free metal. [ c o ( C O ) * a insoluble i n water, soluble i n CS 2, ether, naphtha, alcohol and Ni(CO)^ (2). If these solut ions are kept f o r some time or warmed: decomposition ensues. The pure carbonyl i s unstable i n a i r , forming a v i o l e t basic carbonate. It i s stable however i n an atmosphere of CO or H 2. Cobalt carbonyl hydride i s a yellow gas which Is extremely poisonous and has a very bad odor. If cooled to below -33°C i t forms a pale yellow s o l i d , which on warming melts to a l i g h t yellow l i q u i d , which darkens r a p i d l y due to decomposition into [co(C0)^j 2 and H 2. This reaction has been shown to be r e v e r s i b l e , [ C o ( C 0 ) ^ 2 D e i n S p a r t l y converted into the hydride when heated i n H 2 (120 At.) and CO, at 165°C. (1). The hydride Is r e l a t i v e l y stable i n CO,,and can be d i s t i l l e d i n a stream of CO with p r a c t i c a l l y no decomposition. (10) I t d i s s o l v e s out o f such a s t r e a m , i n water at 0°G., and a l t h o u g h the s o l u t i o n decomposes i n a few m i n u t e s , i t p e r s i s t s l ong , enough f o r a r o u g h e s t imate o f i t s a c i d s t r e n g t h to be made. Coleman ( 1 2 ) c a r r i e d out an e x p e r i m  ent o f t h i s type by p a s s i n g CO c a r r y i n g h y d r i d e vapours t h r o u g h a r o t a r y a b s o r p t i o n tower c o n t a i n i n g 2 0 0 c . c . d i s  t i l l e d water and some m e t h y l o r a n g e . The m e t h y l orange q u i c k l y t u r n e d r e d . P o s t u l a t i n g the a c i d n a t u r e : H C o ( C 0 ) 4 - ^ t i H + + C o ( C 0 ) 4 " and making r o u g h e s t imates o f the amount o f a c i d and i t s n e u t r a l s a l t I n d i c a t e an i o n i z a t i o n cons tant between t h a t - 5 - 4 o f a c e t i c a c i d 1.8*10 , and t h a t o f f o r m i c a c i d , 2*10 • More r e c e n t l y (13) the I o n i z a t i o n c o n s t a n t o f the s i m i i f c a r i r o n c a r b o n y l h y d r i d e , F e l C O j ^ R ^ , has been d e t e r  mined w i t h a f a i r degree o f a c c u r a c y . U s i n g a p o t e n t i o m e t - r i c method, and e x c l u d i n g a l l a i r from the a p p a r a t u s , the - 5 - 1 4 v a l u e s K ^ a 4"<L0 and K^" 4X10 were o b t a i n e d f o r the p r i m a r y and secondary i o n i z a t i o n c o n s t a n t s . R e a c t i o n s o f [ C o ( C 0 ) ^ 2 and Co(C0)^H As a c l a s s the c a r b o n y l s are reajt ive compounds, u n d e r  g o i n g a wide v a r i e t y of s u b s t i t u t i o n and a d d i t i o n r e a c t i o n s . A good many o f the r e a c t i o n s t h a t have been s t u d i e d f o r c o b a l t c a r b o n y l I n v o l v e the f o r m a t i o n o f the h y d r i d e , or the Co(CO)^ i o n as a p r i m a r y s tep i n the r e a c t i o n . ^Co(CO)^]2 i s h y d r o l i z e d i n e i t h e r s t r o n g or weak b a s e s , w i t h the f o r m a t i o n o f the h y d r i d e ( 1 4 ) ( 1 5 ) . W i t h (11) s t r o n g bases such as B a ( 0 H ) 2 or KOH the r e a c t i o n i s : 3 CoCCO)^ 2 V40H^-V4Co(C0)^H + 2 C 0 3 = + 2 [ c o ( C 0 ) 3 [ p o l y m e r At lower hydroxy1 Ion c o n c e n t r a t i o n s (NH^) the r e a c t i o n i s g i v e n b y : 3 Co(CO)^ 2 ^ 4H 20->4Co(G0)^H+2Co(0H) 2 + 8C0 The d i l u t e s o l u t i o n s o b t a i n e d by h y d r o l y s i s reduce methylene b l u e , and are v e r y e a s i l y o x i d i z e d by a i r or m i l d o x i d a n t s , g i v i n g c o b a l t t e t r a c a r b o n y l . C o b a l t c a r b o n y l h y d r i d e a c t s as a weak monobasic a c i d , f o r m i n g t r u e s a l t s w i t h the a l k a l i meta ls and w i t h b u l k y ammine c a t i o n s . I t a l s o forms compounds w i t h the h e a v i e r m e t a l s , but these compounds do not have the p r o p e r t i e s of t r u e s a l t s , but have c o n d u c t i v i t i e s c o r r e s p o n d i n g to weak s a l t s . Prom the r e a c t i o n o f an ammonia s o l u t i o n o f Co(CO)^H, o b t a i n e d by h y d r o l y s i s o f the c a r b o n y l , w i t h s o l u t i o n s o f heavy m e t a l s a l t s , H i e b e r and S c h u l t e i i (14) o b t a i n e d comp ounds o f the f o l l o w i n g t y p e : HCo(CO)^ +- [MeAh]"1"- y[Go(CO)4]2[MeAn]-r-2H+ An *NHoj, amine. Me - va l ence 2 m e t a l . W i t h hexamine c a t i o n s o f v a l e n c e 2 meta l s i t was found t h a t no r e a c t i o n was o b t a i n e d w i t h Z n , Cd or Cu s a l t s o l u t i o n s . W i t h hexamine C o C l 2 s o l u t i o n s [Co(C0)4 ] 2 [Co(NH3 ) 6 j was o b t a i n e d . W i t h N i C l g a s i m i l i a r compound [ C o ( C O ) ^ J 2 [Ni (NH3) 6 J was formed. Gaseous ammonia w i l l a l s o r e a c t d i r e c t l y w i t h (12) cobalt carbonyl: 3 [00(00)^2 +12NH3—>>2 [Co(C0 ) 4 ] 2 L c o(NH 3) 6]+8C0 Both the cobalt and ni c k e l compound are extremely soluble i n water, and therefore d i f f i c u l t to i s o l a t e . They are char acterized by ease of spontaneous decomposition and ammonia loss • With trisphenanthrolene cations sa l t s of the type Jco(CG)^J 2tM(phth)^| are formed, where M <&Co, Ni. These comp ounds are very insoluble i n water and can be used as a method of analysis for Co(C0),H. They are reasonably stable i n the 4 dry state. With HgCl2 and ammoniacal Co(C0)^H the compound Co(C0)^Hg i s precipitated.This compound i s insoluble i n water, soluble In organic solvents. Its formation can be used to detect the presence of Co(C0)^H. It i s unstable, and decomposes i n a short time to a grey powder. With ammoniacal AgNO^ the compound Co(CO)^ Ag^CO^HgO can be i s o l a t e d . This compound i s also insoluble In water and soluble i n organic solvents. In order to determine whether or not they could be considered as true salts of the hydride, Hieber (16) made studies of the conductivities of these compounds and the s i m i l i a r compounds of i r o n carbonyl hydride. He found that i n solutions of methanol and of acetone, the sa l t s formed with the hexammine and with the trisphenanthroline cations had molar conductivities corresponding to solutions of strong e l e c t r o l y t e s . These compounds may therefore be considered (13) as t r u e s a l t s o f the c a r b o n y l h y d r i d e s . The c o n d u c t i v i t i e s decreased w i t h time, i n d i c a t i n g decomposition of the comp ounds i n s o l u t i o n . With the mercury s a l t s however, the molar c o n d u c t i v i t y was very low (0.4 f o r Co(CO).HgCl i n acetone) 4 and I t can be i n f e r r e d t h a t these compounds are not tr u e s a l t s . Hieber expresses the view that s t r u c t u r e s such as Go ( C O ) are not s t a b l e , and can onl y be s t a b i l i z e d by the f o r m a t i o n of s a l t s w i t h complex c a t i o n s . He a l s o s t a t e s - t h a t a l k a l i n e s o l u t i o n s of the hydride c o n t a i n aquo s a l t s r a t h e r than normal s a l t s not yet prepared, and th a t the fo r m a t i o n of metal d e r i v a t i v e s of the hydrides i s by f a r not as g e n e r a l as I t Is supposed to be In an o r d i n a r y f o r m a t i o n of s a l t s . The p r e p a r a t i o n of the anhydrous s a l t s Fe ( C 0)^K 2 and Pe(CO)^KH (13) and measurement of the I o n i z a t i o n constant o f Pe (C0)^H 2 as a weak a c i d , seem t o d i s p r o v e t h i s view. The r e a c t i o n of c o b a l t c a r b o n y l w i t h complex forming amines haa a l s o been s t u d i e d by Hieber and h i s coworkers (17). They f i n d t h a t i n g e n e r a l the amines d i s p l a c e a p a r t of the c a r b o n y l group w i t h the form a t i o n of mixed complexes. When c o b a l t t e t r a c a r b o n y l or c o b a l t t r i c a r b o n y l are p l a c e d i n pyr i d e n e , e f f e r v e s c e n c e due to escap i n g CO ensues, and the compound 003(00)^(C^H^N)^ c r y s t a l l i z e s out. In a s i m i l i a r f a s h i o n the complex 00(00 )3(phth) 2 i s formed w i t h a phenanth- r o l i n e . With a l c o h o l s the compounds C o 2 ( C O ) 5 . C H 3 O H and Co_(CO) c.1 . 5C oH_0H are obtained, and w i t h t h i o a l c o h o l s 2 J 2 5 00(00)3.SC 2H 5 (18). A l l o f these compounds l i b e r a t e Co(CO)^H when t r e a t e d w i t h acids (14) The Structure of Metal Carbonyls. A theory f o r the structure of the monomeric carbonyls has been worked out, which f i t s In with th e i r peculiar properties, such as v o l a t i l i t y , and agrees with the experim ental f a c t s . Although a number of st r u c t u r a l theories have been proposed f o r the polymeric carbonyls, none of these has as yet been completely s a t i s f a c t o r y , and t h e i r structure i s s t i l l somewhat i n doubt. The use.Sdf e f f e c t i v e atomic number (E.A.N.) i n c l a s s  i f y i n g the v o l a t i l e monomeric carbonyls has been found extremely hel p f u l and the properties of the carbonyls show a.marked uniformity according to t h i s c l a s s i f i c a t i o n . The E.A.N, i s defined as the t o t a l number of electrons held within the sphere of the atom, and includes those furnished by the atom I t s e l f , those added by electron transfer, and those added through establishment of covalent and coordinate bonds. Whenever the E.A.N, of the central metal stom of the compound Is equal to that of an inert gas i t i s possible fo r the compound to be v o l a t i l e . In the v o l a t i l e carbonyls It can be shown that the CO groups exist as such i n the molecule and r e t a i n on the whole the bond nature of the CO atom, i . e . :C::sO::. The CO metal l i n k could thus be represented by M:C:::0:;. It can be seen that each CO molecule thus donates one pair of electrons to the central metal atom. Thenif the c r i t e r i o n f o r v o l a t  i l i t y i s the attainment by the metal of the E.A.N, of an (15) i n e r t gas, then f o r example n i c k e l w i t h an atomic number of 28, which i s e i g h t l e s s than the atomic number of krypton, should take up f o u r molecules of CO, forming Ni(CO).. I t A has been found t h a t a l l of the monomeric ca r b o n y l s f o l l o w t h i s r u l e , having c e n t r a l metal atoms w i t h the E.A.N, of r a r e gases* T h i s accounts f o r t h e i r v o l a t i l i t y and a l s o the diamagnetism of the molecules. Elements of odd atomic number cannot a t t a i n the E.A.N, of r a r e gas by the simple c o o r d i n a t i o n of e l e c t r o n p a i r s , and do not form monomeric c a r b o n y l s . In t h e i r h i g h e s t carbonyls the elements of group V l l l b . , to which c o b a l t belongs, c o o r d i n a t e such a number of CO groups as would be expected t o give them as E.A.N, of one l e s s than the r a r e gas s t r u c t u r e , and then combine to form d i m e r i c m o l e c u l e s . The lower c a r b o n y l s formed by many of the elements are a l s o p olymeric, s u g g e s t i n g that the atoms are s t a b i l i z e d i n some way by p o l y m e r i z a t i o n . The polymeric carbonyls are not v o l a t i l e , but i n most cases can be sublimed. To e x p l a i n the case of d i c o b a l t o c t a c a r b o n y l Sidgwick and B a i l e y (19) suggested a g e n e r a l p r i n c i p l e f o r f o r m u l a t  i n g p o l y n u c l e a r c a r b o n y l s and n i t r o s y l s . T h e i r theory was based on the hypothesis that a l l the metal atoms should acquire the E.A.N, of a r a r e gas, and t h a t the CO group can form two c o l l i n e a r c o o r d i n a t e l i n k s . a second c o o r d i n a t e l i n k through the oxygen as donor, l e a d i n g —0= c-« one CO molecule forms (16) to the s t r u c t u r e : ( o=?c —O^Co*- o^c-^Co L * - o ^ a ) 3 T h i s g i v e s one c o b a l t atom an S.A.N, of 37 and the other 35# the e x t r a e l e c t r o n on the former being passed along t o the l a t t e r t o give each the k r y p t o n s t r u c t u r e . A good d e a l of doubt has been c a s t on the s t r u c t u r e s proposed by Sidgwick and B a i l e y , mainly through X-ray c r y - s t a l l o g r a p h i c s t u d i e s on the eneacarbonyl of i r o n , Fe^iGO)^ (20). T h i s compound has been shown to have the s t r u c t u r e : A s i m i l i a r s t r u c t u r e f o r Co(CO)^ 2 w ° u l d be: <LZo These s t r u c t u r e s however leave each atom w i t h one u n p a i r e d e l e c t r o n i c s p i n , and the molecules should be paramagnetic. T h e i r diamagnetism can o n l y be e x p l a i n e d by the h y p othesis that the two metal atoms are so c l o s e t o g e t h e r that the e l e c t r o n s p i n s are p a i r e d , even though no bond Is formed. K.A. Jensen (21) has more r e c e n t l y suggested l i n k i n g of the b r i d g e groups by resonance between the forms M [ A M i v i n \A T h i s f i t s the observed bond le n g t h s of Fe^CO)*?, andaccounts (17) f o r the d iamagnet i sm o f the m o l e c u l e . The s t r u c t u r a l p r i n c i p l e u n d e r l y i n g the c o m p o s i t i o n o f the s e r i e s P e ( C O ) 4 H 2 Go(CO)^H N i ( C O ) ^ seems to be the a t ta inment of the c l o s e d e l e c t r o n i c c o n f  i g u r a t i o n o f N i ( C O ) ^ . i n the c a r b o n y l h y d r i d e s i t i s p o s s i b l e f o r atoms of odd atomic number to a t t a i n the e f f e c t i v e atomic number of a r a r e gas , s i n c e I t can be assumed that the hydrogen atom donates one e l e c t r o n to the c e n t r a l meta l atom. T h i s may e x p l a i n why, i n many r e a c t i o n s , c o b a l t c a r b o n y l h y d r i d e is formed i n p r e f e r e n c e to the o c t a c a r b o n y l . The c a r b o n y l h y d r i d e s have been shown by e l e c t r o n d i f f r a c t i o n measur ements (22) t o be i s o e l e c t r o n i c w i t h 111(00)^. The mode o f l i n k a g e o f the hydrogen i s however not d e f i n i t e l y e s t  a b l i s h e d by the e l e c t r o n d i f f r a c t i o n d a t a . H i e b e r (23), (24) h o l d s the view tha t the hydrogen atoms are i n c o r p  o r a t e d i n some way as p r o t o n s w i t h i n the core o f the c o b a l t and i r o n atoms. T h i s s t r u c t u r e however does not conform w i t h the observed a c i d na ture of the h y d r i d e s . Evans and L i s t e r (25) have sugges ted t h a t the hydrogen is s i t u a t e d at the end of the c h a i n M - C - O - H . T h i s s t r u c  t u r e agrees w i t h e l e c t r o n d i f f r a c t i o n measurements and a l s o is i n agreement w i t h the p r o p e r t i e s o f the h y d r i d e s . Oxygen r a r e l y as sumes a c o v a l e n c y o f f o u r , and i t i s t h e r e f o r e not s u r p r i s i n g t h a t the hydrogen i s e a s i l y l o s t . L i b e r  a t i o n o f a hydrogen atom accounts f o r the r e d u c i n g power (18) and I n s t a b i l i t y of these compounds;, which decompose at a temperature w e l l below room temperature. They may also dissociate as an ion: M:C:::0:H^=i MrC:::Or+H + allowing the hydride to form sa l t s such as for example Co(CO)^K and [Co(C0)^ 2 [Co(phth)-J . While the chemical properties of the hydrides seem to agree with t h i s struc ture, there has as yet been no evidence advanced to show that there are two types of M-C and C-0 bond dimensions within the molecule, as would be expected for a structure of t h i s type. (19) II* Introduction. The object of this work was to prepare the compound [co(CO)4] 2[Oo(phth)-3j (phth e o-phenanthroline), and by transference measurements to determine i f possible the r e l a t i o n which i t bears to the Co(CO)^ ion. E i t h e r the Co(CO)^ ion or the Co(phth) ion could be traced by the use of radioactive cobalt, i^was assumed that there was no exchange between the two cobalt atoms i n the compound, but this was l a t e r proved not to be the case. D i f f i c u l t i e s were encountered because of the extreme I n s t a b i l i t y of the compound, and only very rough measurements were obtained. Approximate measurements of the molal conductivity i n benzaldehyde and acetophen- one were also made, and these compared favorably with measurements made on s i m i l i a r cimpounds (16), i n d i c a t i n g that the compound i s a strong e l e c t r o l y t e . The s o l u b i l i t y of the compound and i t s s t a b i l i t y i n various organic solvents were determined* Because of the r e s u l t s obtained i n the transference measurements, the exchange between cobalt (11) ions + + and the Co(phth), ion was studied. (20) I I I . Experimental. The radioactive Co^ G used was prepared i n the p i l e at Chalk River by i r r a d i a t i n g C 0 2 O 3 . The oxide was d i s s  olved i n concentrated hydrochloric acid and the solut i o n neutralized with ammonium hydroxide. Por the experiments an exchange CoC^.SH^O was added to the solution of active cobalt to give the desired s p e c i f i c a c t i v i t y , and the amount of cobalt i n a given volume was determined using the^-nitroso^3 -napthol method (26). portions of the solution were then counted to obtain the number of counts per gram of cobalt. The counting c i r c u i t consisted of an argon methonal f i l l e d G-eiger tube attached to a scal i n g c i r c u i t . The tube had a plateau of about 300 volts with about a 1% r i s e . The background remained constant over the period of oper ation. The samples were counted on small watch glasses, held i n position on an aluminum tray, and were t h i n enough that i n t e r n a l absorption could be neglected. The standard and samples were counted under i d e n t i c a l cond- 60 i t i o n s of geometry. The half l i f e of fi v e years for Co i s long enough so that decay of the active cobalt, over the period of measurement; could be neglected. F i g u r e I. (21) P r e p a r a t i o n of D l o o b a l t Q c t a c a r b o n y l . D i c o b a l t o c t a c a r b o n y l was prepared by the method o u t l i n e d by Gilmont and Blanchard (11) u s i n g the samB amounts of reagents as d e s c r i b e d by them, i n t h i s p r o c  edure the a l k a l i s a l t of c o b a l t t e t r a c a r b o n y l hydride i s f i r s t prepared by shaking an a l k a l i n e c o b a l t ( I I ) cyanide suspension i n the presence of carbon monoxide.. A shaker of the type shown i n f i g . l was used and the carbon monox ide was passed i n a slow stream through the apparatus . d u r i n g the shaking p r o c e s s . The Co(CO)^K formed i s very e a s i l y o x i d i z e d and i t was found t h a t any t r a c e of a i r In the apparatus l e d to darkening of the suspension, and no Co(CO)^K was o b t a i n e d . To prevent a i r e n t e r i n g the e x i t sidearm d u r i n g the shaking a trap was attached c o n s i s t i n g of a g l a s s tube j u s t t ouching the s u r f a c e of a s m a l l amount of water contained i n a 500ml. f l a s k . T h i s procedure was found to be e f f e c t i v e i n p r e v e n t i n g the o x i d a t i o n of the Co^Oj^K* Cobalt c a r b o n y l hydride was l i b e r a t e d from the s o l  u t i o n of the potassium s a l t by the a d d i t i o n of 12N hydro c h l o r i c a c i d . The set-up used f o r c o l l e c t i n g the hydride i s shown i n f i g . 2 . The s o l u t i o n was swept w i t h CO f o r about t e n hours and the hydride c o l l e c t e d i n a U-shaped tube c o o l e d t o - 79°C. In dry i c e - a l c o h o l mixture. When the hydride had been c o l l e c t e d the tube c o n t a i n i n g i t was evacuated at - 7 9 ° and then allowed t o come t o room temperature. The Co(CO).H melts t o a l i g h t y e l l o w l i q u i d F i g u r e I I . (22) which darkens r a p i d l y due to decomposition into^Co(CO)) The d i c o b a l t o c t a c a r b o n y l formed i n t h i s manner i s a dark brown m i c r o c r y s t a l l i n e s o l i d . I t decomposes i n the presence of a i r t o give a v i o l e t b a s i c carbonate. I t i s s t a b l e i n an atmosphere of carbon monoxide or hydr ogen, and i t was found that i t c o u l d be kept without decomposition i n the tube i n which i t had been prepared i f no a i r was allowed t o e n t e r . Most of the [Co (00 ) 4 ^ 2 c o u l d be removed from the tube f o r use by g e n t l y t a p p i n g the s i d e s of the tube. Any that c o u l d not be removed In t h i s manner was washed out w i t h the p a r t i c u l a r s o l v e n t to be used, u s u a l l y c o n c e n t r a t e d NH/OH. (23) Preparation of [ 0 0 ( 0 0 ) 4 ] 2 (p°(phth)^ \p°(C0)^2 [Co(phth)3] was prepared by shaking f o r 36 hours ^00(00)4^2 with concentrated N H 4 O H , i n the r a t i o 1.25gms. [ 0 0 ( 0 0 ) 4 ] 2 P e r 150mls. N H 4 O H . It was found that a i r must be excluded from the apparatus during shaking, or a dark red sulution i s obtained which w i l l not prec i p i t a t e the phenanthroline complex. To accomplish t h i s a stopcock was attached to the shaking f l a s k so that the system could be evacuated after the carbonyl had been weighed, and the N H 4 O H then added. The colorless or f a i n t l y pink solution prepared i n this way was added to an equal volume of solution containing 0.6gms. CoCl2» 6H2O and 1.4gms. o-phenanthroline monohydrate per 50mls. water* The heavy flocculent reddish brown pr e c i p i t a t e which immediately formed was f i l t e r e d through a Gooch cr u c i b l e , washed with water, and dried i n a vacuum dess- ic a t o r under high vacuum. It was found to be unstable, decomposing to a grey brown substance which would not dissolve In any of the solvents which dissolve the o r i g i n a l compound. The decomposition of the product depends to a large degree on the r a p i d i t y with which i t i s dried. Washing the precipitate with Water and drying i t i n a vacuum dessicator was found to generally res u l t i n p a r t i a l decomposition, unless the amount of pre c i p i t a t e was extremely small, allowing rapid drying. If the precipitate was washed with ether or alcohol to remove the water, i t was found to decompose very l i t t l e during drying and (24) eould be kept for several days over P 2 O 5 . The p r e c i p i t  ate i s s l i g h t l y soluble i n these substances, but the rate of solution seems to be slow and the amount of product l o s t during the washing was amply compensated f o r by lack of decomposition during drying. Hieber and Schulten (14.) state that the compound Is r e l a t i v e l y stable i n the dry state. It was found however that even when thoroughly dry i t could not be kept more than a few days without considerable decomposition taking place. Storage i n an atmosphere of carbon monoxide did not seem to a l t e r the rate of decomposition. These workers p u r i f i e d the product by di s s o l v i n g i t In a l i t t l e acetone, f i l t e r i n g the solution and r e p r e c i p i t a t i n g the compound with water. This procedure however leads to further decomposition during the drying, and no attempt was made i n these experiments to puri f y the compound i n t h i s manner. If p a r t i a l decomposition had set i n the compound was d i s s  olved i n the p a r t i c u l a r solvent to be used, and the i n s o l  uble residue f i l t e r e d out. In transference and exchange measurements one or other of the two cobalt atoms was radioactive. Wherever possible the cobalt i n Co(phth)^ 4 was made active, since making the carbonyl cobalt atom active involves the hand- l i n g of the extremely v o l a t i l e Co (CO)^H. In order to make the cobalt atom i n the phenanthroline complex active a given volume of standard radioactive solution was added to orthophenanthroline and enough (25) enough CoCl2»6H20 then added to give the necessary weight of CoCI •[cofCO)^^ [Cofphth)^] was then p r e c i p i t a t e d by the addition of ammoniacal cobalt carbonyl s o l u t i o n . I f i t was necessary to make the cobalt carbonyl active, the active cobalt chloride solution was added i n the prep aration of the carbonyl. S o l u b i l i t y of [00(00)4] 2 j p o(phth ) 3 J . [coCCO)^! 2 |J is solves r e a d i l y i n acetone forming an orange-brown solution. Upon standing t h i s s o l u t i o n gradually turns cloudy, and eventually a f l o c c - ulent dark brown precipitate i s formed. If the cobalt atom i n the phenanthrollne complex i s made active, almost a l l of the a c t i v i t y i s removed by f i l t e r i n g off t h i s prec i p i t a t e . When analysed radiochemically i t showed 2.5$ active cobalt. It Is soluble i n water, forming a pale yellow s o l u t i o n . It was thought that the decomposition of the compound i n acetone might be due to the presence of small ampunts of water i n the acetone used. The acetone was accordingly r e d i s t i l l e d over activated alumina to remove any traces of water. It was found however that the compound was s t i l l , unstable i n t h i s solvent. The s o l u b i l i t y and s t a b i l i t y of the compound were measured i n various other organic solvents i n an e f f o r t to f i n d a solvent i n which i t was more stable. The r e s u l t s obtained are given i n table I I . The acetone used was (26) C.P. grade and was dried i n the method described. It had a b o i l i n g point of 56.5 C. No attempt was made to p u r i f y any of the other solvents used, but they were a l l of C.P. grade. The JCO(CO)^J 2.|Co(phth)^1 was p u r i f i e d by d i s s o l v i n g i t i n acetone, f i l t e r i n g o f f the insoluble residue, and evaporating the solution-to dryness under reduced pressure. The compound prepared i n th i s manner was completely s o l  uble In acetone. The s o l u b i l i t y of equal amounts of compound i n equal amounts of solvent were tested at room temperature for the following solvents. Table I I . Solvent. acetone. methyl ethyl ketone. acetophenone. methyl p a r a t o l y l ketone. formaldehyde benzaldehyde sallcylaldehyde Cannamaldehyde benzene ether absolute ethanol S o l u b i l i t y -r- s i . s o l . -r- •h s i . s o l . dissolves slowly S t a b i l i t y . heavy ppt. overnight s l i g h t ppt. 1 hr. heavy overnight s l i g h t ppt. overnight ppt. i n few hrs. no , ppt. no ppt. no ppt. ethyl acetate heavy ppt. i n few hrs. (27) I f the s t a b i l i t y of the compound i n v a r i o u s s o l v e n t s i s judged by the r a p i d i t y w i t h which an i n s o l u b l e p r e c i p  i t a t e Is formed, i t would appear that the compound Is unstable i n ketones, s t a b l e i n aldehydes. However i f the p r e c i p i t a t e formed i n an acetone s o l u t i o n i s f i l t e r e d o f f , and i t s s o l u b i l i t y t e s t e d i n the v a r i o u s aldehydes used, i t i s found to be s o l u b l e . The apparent s t a b i l i t y of the compound i n aldehydes t h e r e f o r e appears to be due o n l y to the s o l u b i l i t y of the products of d i s i n t e g r a t i o n i n these s o l v e n t s • The Conductance of LCo(C0)^j2 [ p 0 ( P n t ] a ) - J i n Benzaldehyde and Acetophenone. As a r e s u l t of the s o l u b i l i t y measurements and the f a c t t h a t [co(CO) 4J 2 (Cofphth)^] appears to be more s t a b l e i n benzaldehyde or acetophenone than i t i s i n acetone, the m o l a l conductance of the compound i n these s o l v e n t s was determined to see I f they would be s u i t a b l e as s o l v  ents f o r t r a n s f e r e n c e measurements. Since the I n s t a b i l i t y of the compound precludes making accurate measurements of the conductance, o n l y very approximate values were o b t a i n e d . The r e s i s t a n c e of the s o l u t i o n s was measured i n the f o l l o w i n g manner. The s o l u t i o n was c o n t a i n e d i n a weighing b o t t l e , and two s i l v e r e l e c t r o d e s , approximately 1cm. square, were i n s e r t e d i n t o the s o l u t i o n through a rubber stopper. R e s i s t a n c e across, the two e l e c t r o d e s was measured w i t h a Simpson r e s i s t a n c e meter. The c e l l was s t a n d a r -(28) d i z e d by measuring the r e s i s t a n c e of an equal volume of O.lM KC1 s o l u t i o n . The f o l l o w i n g r e s u l t s were o b t a i n e d : Benzaldehyde: cone. - O.OOO84.M r e s i s t a n c e o f pure benzaldehyde - 1.2x10 -d- Table I I I . Time R e s i s t a n c e Time R e s i s t a n c e 0 min. 8*10^ -TV 45 min. 6.5*10^ 1 4 5 7.5*10 4 60 6.0>10 j 4 10 7.8*10* 150 5.3-*10 17 7.8/10* 1110 6.2*10 4 1 4 26 7.4*10*" 1170 6.2*10 Acetophenone: cone. - 0.0023M 4 r e s i s t a n c e of pure acetophenone - 24*10 -H— Table I V . Time Re s i s t a n c e Time R e s i s t a n c e 0 min. 3 * 1 0 * 105 min. 17.0x10^ S\- 5 3.6*10* 18 h r s . 13.5x10* 10 4.0X10 4 19 13.0*10* 15 4.4X104 , 20 12.7*10* 4 4 25 5.3vlO 22 11.7*10* 40 8.0X10 4 23 11.0*10* 75 16 . 0 v l 0 * 24 10.5*10* Por a O.lM KC1 s o l n : R-1500 T - 20°C (29) Prom the r e s i s t a n c e i n the c e l l of 0.1M K C l , the c e l l constant J was c a l c u l a t e d , u s i n g the r e l a t i o n J - LR where L = t h e s p e c i f i c conductance R =the measured r e s i s t a n c e At 18°C. the s p e c i f i c conductance of 0.1 demal KCl i s 0.011166-A- 1 (27). The demal s o l u t i o n IS d e f i n e d as a s o l u t i o n c o n t a i n i n g a gram mol. of s a l t d i s s o l v e d i n ^ . . ^ ^ a c u b i c decimeter of s o l u t i o n at /-zero degrees-2 The c o r r  e c t i o n s i n v o l v e d i n changing t h i s to molar c o n c e n t r a t i o n are o u t s i d e the accuracy obtained In the above conductance measurements. Knowing the c e l l c o n s t a n t , the s p e c i f i c conductance of the [ c o t C O j ^ ^ L 0 0 ^ * 1 * * 1 ^ ] s o l u t i o n s were c a l c u l a t e d from the measured r e s i s t a n c e s , the conductance due to the s o l v e n t being s u b t r a c t e d from the conductance of the s o l  u t i o n . The molar conductance was then c a l c u l a t e d u s i n g the r e l a t i o n , A m - 1000 L where/\m - molar conductance 0 0 = c o n c e n t r a t i o n of s o l u t i o n i n m o l e s / l i t e r . The values g i v e n are f o r the i n i t i a l readings only, b e f o r e the s o l u t i o n s had decomposed to any ex t e n t . Table V. Molar C o n d u c t i v i t y of Cco(CO)/|1?CCo(phth) ?3  Solvent J Cone. L£}?~ -A m rv^ Benzaldehyde O . 8 4 10" 3 1.95 l O " 4 - 232 1 6 * 7 -3 - / Acetophenone 2.3 10 ^ 5.57 10 4 212 (30) Hieber (16) has measured the c o n d u c t i v i t y of compounds s i m i l i a r t o t h i s , In methanol and acetone. Some of h i s r e s u l t s are shown i n t a b l e VIt Table V I . Compound Solvent A m. -Q- 1  [ F e H ( C 0 ) 4 ] 2 [ N i ( p h t h ) 3 ] Cfi^OH 129.7 [FeH ( C 0 ) 4 ] 2 [ N i ( p h t h ) 3 l Acetone 114.0 ^ G ( C 0 ) j 2 [ N i ( p h t h ) 3 ] Acetone 248.8-280.15 JFeHtCO)^] 2 [Co(phth)3] Acetone 168.4 Measurements made i n acetone s o l u t i o n s showed that the c o n d u c t i v i t i e s decreased w i t h time. Table V I I Compound m i v 1  ^FeE(C0)j.]2[E±(m3)6\ 1 ] L4.5 88 . 4(75') 7A.2.(4hr.) 4 4.1(25hrs.) [ F e H ( C 0 ) 4 ] 2 [ C o ( N H 3 ) g 133.5 102 . 4(15') 99.5(25') 95.6(50') From c o n d u c t i v i t y measurements of ( C o t C O ^ ^ f c o t p h t h ) ^ i n benzaldehyde i t can be seen t h a t the r e s i s t a n c e d e c r  eases w i t h time, i n d i c a t i n g an i n c r e a s e i n c o n d u c t i v i t y . T h i s r e s u l t may be due to the f a c t that benzaldehyde i s e a s i l y o x i d i z e d to benzoic a c i d , which would c o n t r i b u t e to the c o n d u c t i v i t y of the s o l u t i o n . In acetophenone the c o n d u c t i v i t y decreases at f i r s t , then i n c r e a s e s s l i g h t l y . The decrease i n a c t i v i t y can be (31) a t t r i b u t e d to d e c o m p o s i t i o n o f the s o l u t e . The subsequent i n c r e a s e may be due to the f a c t tha t i n the course o f d e c - o m p o s i t i o n i o n s , s u c h as Co , may be formed w h i c h are s o l u b l e i n acetophenone and l e a d to an i n c r e a s e i n the c o n d u c t i v i t y . S i n c e the molar c o n d u c t i v i t y of a s o l u t i o n i s e q u a l t o the sum of the molar c o n d u c t i v i t i e s o f the i ons p r e s e n t , the molar c o n d u c t i v i t y of [ C o ( C 0 ) ^ 2 [Co(phth)^]can be c a l c u l a t e d from the d a t a g i v e n by H i e b e r i n t a b l e V I . T h i s c a l c u l a t i o n g i v e s a va lue o f 303.2 - 334«6X\3" f o r the molar c o n d u c t i v i t y o f [ c o C C O ) ^ ^ (co ( p h t h ) 3 ^ i n a c e t o n e . The h i g h e r the d i e l e c t r i c cons tant o f the s o l v e n t , the h i g h e r w i l l be the c o n d u c t i v i t y i n t h a t s o l v e n t . The d i e l e c t r i c c o n s t a n t s o f ace tone , acetophenone and b e n z  aldehyde are 2 0 . 4 , 18.6 and 18 r e s p e c t i v e l y . I t can t h e r e f o r e be seen t h a t the v a l u e s o f 232 f o r the molar c o n d u c t i v i t y i n b e n z a l d e h y d e , and 212 f o r the molar c o n d u c t i v i t y i n acetophenone, agree w i t h i n e x p e r i m e n t a l e r r o r w i t h the v a l u e o b t a i n e d by H i e b e r i n a c e t o n e . T r a n s f e r e n c e Measurements . A t r a n s f e r e n c e c e l l of the type d e s i g n e d by Washburn (28) was used i n an attempt to measure t r a n s f e r e n c e numbers o f [co (C0)^j 2[co ( p h t h ) ^ j i n s o l u t i o n s o f acetone and a c e t o  phenone. The c e l l had a volume of a p p r o x i m a t e l y l O O m l s . and a d i s t a n c e between e l e c t r o d e s o f 45cms. The e l e c t r o d e s were o f p l a t i n u m and were s e t i n h o r i z o n t a l l y t h r o u g h F i g u r e I I I (32) ground g l a s s stoppers so that they c o u l d be removed f o r c o u n t i n g . I t was found to be impossible to o b t a i n r e s u l t s w i t h a c e l l of t h i s type, because of the f o l l o w i n g d i f f i c u l t i e s I In an acetone s o l u t i o n the compound showed sig n s of decomposition by the f o r m a t i o n of a p r e c i p i t a t e , b e f o r e the current had been passed l o n g enough to secure a c c u r a t e r e s u l t s . With decomposition the c u r r e n t through the c e l l dropped r a p i d l y , r e s u l t i n g i n p r a c t i c a l l y no c u r r e n t at the end of about an hour. In acetophenone the compound was more s t a b l e , but a l s o l e s s s o l u b l e , so t h a t o n l y very d i l u t e s o l u t i o n s c o u l d be prepared. The r e s i s t a n c e of these s o l u t i o n s was so h i g h t h a t very l i t t l e c u r r e n t flowed through the c e l l , even be f o r e decomposition had set i n . To overcome these d i f f i c u l t i e s a e e l l o f the H i t t o r f type was designed, having a volume of approximately 25ml. and a d i s t a n c e between e l e c t r o d e s of 8cm. With a c e l l of these dimensions the r e s i s t a n c e of the s o l u t i o n i s much reduced, and measurements can be made i n a s h o r t e r time b e f o r e the s o l u t i o n has time to decompose a p p r e c i a b l y . The c e l l t h a t was used i s shown i n f i g . 3« The e l e c t r o d e s were of platinum and were set i n through ground g l a s s j o i n t s , w i t h the cathode at the bottom. T h i s helps to prevent mixing, s i n c e the [Go(phth) 3] which presumably migrates to the cathode, i s h e a v i e r than the [ 0 0 ( 0 0 ) 4 ] i o n . « o o o ^ Potentiometer s/wv G K X K 2 Standard 100 R e s i s t a n c e . To t r a n s f e r e n c e F i g u r e IV. " c e l l . (33) The cathode was set i n through the side of the c e l l , so t h a t i t c o u l d be removed e a s i l y to count any p r e c i p i t a t e formed on i t , and was cup shaped so that i t would h o l d the p r e c i p i t a t e more e a s i l y . The stopcock at the bottom was f o r the purpose of removing the s o l u t i o n from the c e l l , but i t was found that i f the s o l u t i o n was removed i n t h i s way mixing r e s u l t e d from some of the cathode p o r t i o n remaining i n the s i d e arm and running out w i t h the anode p o r t i o n . The anode and middle p o r t i o n s were t h e r e f o r e removed w i t h a s u c t i o n p i p e t t e from the top of the c e l l , and the cathode p o r t i o n t h e n r u n out from the bottom. To t e s t whether or not mixing r e s u l t e d when the s o l u t i o n was removed i n t h i s manner a few c r y s t a l s of potassium permanganate were p l a c e d i n the cathode p o r t i o n and the c e l l f i l l e d w i t h water, g i v i n g a c o l o r e d s o l u t i o n around the cathode. No m i x i n g of the s o l u t i o n c ould be observed when i t was removed i n the manner d e s c r i b e d . The c i r c u i t used i s shown i n the diagram. I t was found t h a t f o r the s m a l l number of coulombs passed d u r i n g a measurement a s i l v e r coulometer would not g i v e s u f f i c i e n  t l y accurate r e s u l t s . A potentiometer was used to measure the v o l t a g e drop across a standard hundred ohm r e s i s t a n c e connected i n s e r i e s w i t h the t r a n s f e r e n c e c e l l . The c i r c u i t used i s shown i n f i g . A . The potentiometer was s t a n d a r d i z e d against a standard Weston c e l l before the (34 ) ru n and s e v e r a l times d u r i n g measurements. The v o l t a g e drop across the standard r e s i s t a n c e was measured every few minutes d u r i n g a run, and from the c a l c u l a t e d c u r r e n t a graph was p l o t t e d of c u r r e n t v s . time. The area under the curve r e p r e s e n t e d the number of coulombs passed. Procedure; T r a n s f e r e n c e measurements were made i n s o l u t i o n s of acetone. The acetone was C.P. grade and was r e d i s t i l l e d s e v e r a l times over a c t i v a t e d alumina t o remove any water. The [ C o ( G 0 ) 4 j 2 [ C o ( p h t h ) 3 J was d i s s o l v e d i n the acetone, and any i n s o l u b l e r e s i d u e t h a t remained due to decompos i t i o n was f i l t e r e d o f f . The cathode and anode were weighed a c c u r a t e l y and a f t e r the s o l u t i o n had been i n t r o d u c e d i n t o the c e l l , were s e a l e d i n w i t h p a r a f f i n . A f t e r the c u r r e n t had been passed f o r the d e s i r e d l e n g t h of time the anode was c a r e f u l l y removed, and the s o l u t i o n drawn out as des c r i b e d i n t o weighed g l a s s stoppered b o t t l e s , and the three p o r t i o n s weighed. The s o l u t i o n s were kept t i g h t l y stoppered to prevent e v a p o r a t i o n of acetone. The s o l u t i o n was drawn out i n three p o r t i o n s , the anode p o r t i o n extending to about two cm. below the anode, the middle p o r t i o n to about two cm. above the cathode, the remaining s o l u t i o n b e i n g run out as the cathode p o r t i o n . During e l e c t r o l y s i s a heavy dark brown p r e c i p i t a t e was formed on the cathode. T h i s was removed, washed w i t h acetone, and weighed. The anode was a l s o weighed a f t e r each run, but no weight d i f f e r e n c e was found. A gas (35) appeared t o be formed at b o t h the anode and cathode, but was not c o l l e c t e d i n s u f f i c i e n t q u a n t i t i e s to be i d e n t i f i e d . The c o n c e n t r a t i o n of the o r i g i n a l s o l u t i o n was obt a i n e d by e v a p o r a t i n g known volumes to dryness, o b t a i n i n g the weight of the [co(G0)^]2 [oo(phth) 3"] i n t h i s volume, and then c o u n t i n g the samples. The c o n c e n t r a t i o n of the three p o r t i o n s a f t e r e l e c t r o l y s i s c o u l d then be obtained by e v a p o r a t i n g known volumes to dryness and c o u n t i n g them under the same c o n d i t i o n s . The p r e c i p i t a t e on the cathode was a l s o counted, and from i t s weight the percent a c t i v e c o b a l t c a l c u l a t e d , prom the weight of the p r e c i p i t a t e on the cathode and the number of coulombs passed i t should be p o s s i b l e to c a l c  u l a t e the e q u i v a l e n t weight of the p r e c i p i t a t e . No c o n s i s  t e n t r e s u l t s c o u l d be ob t a i n e d however, probably due to the f a c t t h a t the p r e c i p i t a t e d i d not adhere to the cathode very w e l l , and was probably not a l l removed f o r weighing. R e s u l t s and C a l c u l a t i o n s ; T ransference numbers were c a l c u l a t e d , assuming the f o l l o w i n g r e a c t i o n s to take p l a c e : anode: 2JCo(C0)J" > Co(CO)^ 2 + 2E cathode: . E20^±E*+ OH" [Co(phth)3]+++ 20H"—>[Co(phth) 3](OH) 2 2H* + 2E-—»H2 at anode: g a i n t_ equiv. [00(00)4] +4- l o s e t + e q u i v . [Co (phth) oJ (36) at cathode: l o s e t _ equiv. [co((iCO)^J g a i n t+ equiv. [Go(phth)^j[ d e p o s i t 1 equiv. ^ ( p h t h ) . ^ (GH) 2 net r e s u l t : r -H-l o s e (1 - t + ) equiv. - t - equiv. (Co(phth ) 3 J The c o b a l t atom i n [bo(phth)-^j was made a c t i v e . At the end o f the r u n the middle p o r t i o n had changed c o n c e n t r a t  i o n . S i n c e i t s f i n a l c o n c e n t r a t i o n was the samB as that o f the cathode p o r t i o n , the two were taken t o g e t h e r . Table V I I I . cts./min.* cone. volume equiv . 10.2ml. e q u i v . / l . i n mis. t r a n s f e r r e d o r i g i n a l cathode middle anode 2398 t 28 2291 t 3 0 2288 ?38 2151 0.0117 0 . 0 1 1 3 0 . 0 1 1 3 0.0106 1 0 . 0 0 5 2 . 0 2 2 . 0 5 coulombs passed * 0.83 -6 3.8 *10 0.81x10 -6 2.20*10 -6 -8.6x10 faradays * Background s u b t r a c t e d . Transference numbers c a l c u l a t e d : (1) from change i n cone, of anode p o r t i o n : t =0.256 + t_ = 0.74.4 (2) from change i n cone, of cathode p o r t i o n : t-'0.465 •? t - 0.535 (37) The p r e c i p i t a t e on the cathode was dark brown i n c o l o u r , w i t h a s m a l l amount of l i g h t e r brown m a t e r i a l on the s u r f a c e . I t was s o l u b l e i n water, forming a y e l l o w s o l u t i o n * C a l c u l a t i o n of i t s e q u i v a l e n t weight, from the weight of p r e c i p i t a t e d e p o s i t e d and the number of coulombs passed, gave the f o l l o w i n g r e s u l t s , i n c l u d i n g values o b t a i n e d i n previous runs: Table IX. Wt. of ppt. Coulombs. E q u i v . W t . ^ n i ) 0.0036 gms. 0.83 420 0.0176 5.18 293 0.0176 5 . 4 5 312 0.0026 1.167 216 A r a d i o c h e m i c a l a n a l y s i s of the p r e c i p i t a t e gave the f o l l o w i n g r e s u l t s : Table X. Wt. p p t . Counts/min. Gms. Co % Co  0.0067gms. 4533 ^ 33 0.00025 3.76 0.0118 7241 ± 4 1 0 . 0 0 0 4 0 3 . 4 1 0.0103 6549 * 3 9 0.00036 3 . 5 3 Ave. - 3.57$ I f the p r e c i p i t a t e Is [Cotphth^ J (0H) 2 the f o l l o w i n g values s h o u l d be obt a i n e d : M o l e c u l a r weight - 616.2 E q u i v a l e n t weight - 308.1 Percent a c t i v e c o b a l t - 9 . 5 8 $ (assuming no exchange) ( 3 8 ) Measurements were a l s o made w i t h the c o b a l t I n the [ 0 0 ( 0 0 ) 4 ! " " i o n a c t i v e . The r e s u l t s o b t a i n e d were too i n a c c u r a t e t o c a l c u l a t e t r a n s f e r e n c e numbers, as the d i f f  erence i n c o n c e n t r a t i o n between the cathode p o r t i o n and the o r i g i n a l s o l u t i o n was too small t o be s i g n i f i c a n t . The anode p o r t i o n showed a d e f i n i t e i n c r e a s e i n a c t i v i t y , which agrees w i t h the equations p o s t u l a t e d . The p r e c i p i t a t e on the cathode'however was found to be a c t i v e . I f t h i s p r e c i p i t g t e Is ^CoCphth)^ (OH) 2 as has been p o s t u l a t e d , i t should not have been a c t i v e i n t h i s case, u n l e s s exchange had occured between the two c o b a l t atoms. A n a l y s i s of the p r e c i p i t a t e showed t h a t i t c o n t a i n e d 6 . 7 $ a c t i v e c o b a l t , a much l a r g e r percentage than was found when the c o b a l t i n the ph e n a n t h r o l i n e complex was a c t i v e . An attempt was made to analyse the p r e c i p i t a t e f o r t o t a l c o b a l t content u s i n g the - nitrosoy9 naphthol method. However i t was found that o n l y a very s m a l l amount of the c o b a l t c o u l d be p r e c i p i t a t e d i n t h i s manner, s i n c e the o r t h o - p h e n a n t h r o l i n e complex prevents the p r e c i p i t a t i o n of c o b a l t In the u s u a l manner. (39) Study o f Exchange between the Two Cobalt Atoms In [ c o f c o j^fcofphth)^ Because of the r e s u l t s obtained i n the t r a n s f e r e n c e measurements, which seem to i n d i c a t e exchange of some type, an experiment was c a r r i e d out to determine whether or not exchange occurs between the two c o b a l t atoms i n [ C o ( C 0 ) 4 J 2 ( c o ( p h t h ) 3 ] . Because of the weak a c i d nature of Co(CO)^H, i t should be p o s s i b l e t o l i b e r a t e Co(CO)^H from ( C o ( C O ) ^ l 2 ~ |co(phth)3] by the a d d i t i o n of a s t r o n g a c i d such as HCl, and t h i s was found to be the case. The a c t i v i t y of t h i s w i l l be a measure of the exchange i f o n l y the phenanth- r o l i n e Co was a c t i v e i n i t i a l l y . ( p o ( C 0 ) ^ 2 ( C o f p h t h ) ^ w a s prepared as p r e v i o u s l y , w i t h the c o b a l t atom in' the phena n t h r o l i n e complex a c t i v e . The p r e c i p i t a t e was washed w e l l w i t h water, but no attempt was made to dry i t . A s m a l l d i s t i l l i n g f l a s k was conn e c t e d through the s i d e arm to a d r y i n g t r a i n , and a tr a p c o o l e d t o - 7 9 * C . The p r e c i p i t a t e was washed i n t o the d r y i n g f l a s k w i t h a small amount of d i s t i l l e d water, the system was attached to the carbon monoxide generator and concentrated h y d r o c h l o r i c a c i d added u n t i l the p r e c i p i t a t e completely d i s s o l v e d , g i v i n g a b r i g h t blue s o l u t i o n . About an hour e l a p s e d between the time the compound was made, and the time that i t was a c i d i f i e d . A slow stream of carbon monoxide was allowed to pass f o r about t e n hours (40) at the end of which time a s m a l l amount of 00(00)46: had c o l l e c t e d i n the t r a p . The t r a p was evacuated at -79°C. and allowed to come to room temperature, g i v i n g d i c o b a l t o c t a c a r b o n y l . - T h i s was d i s s o l v e d i n benzene, evaporated t o dryness, and counted. background - 61*3 0 0 ( 0 0 ) 4 2 - 60*3 T h i s i n d i c a t e s t hat there was no exchange between the two c o b a l t atoms, under the c o n d i t i o n s of the experiment. Study of the Exchange Between Co and Qco(phth) 3j • Since i t appears that there i s no exchange between the two c o b a l t atoms i n [ 0 0 ( 0 0 ) 4 ] 2 [po(phth) 3], some other e x p l a n a t i o n must be sought to account f o r the r e s u l t s o b t ained i n t r a n s f e r e n c e measurements. I f the £co(C0)^l i o n were to decompose i n acetone s o l u t i o n , g i v i n g c o b a l t i o n s , i t might be p o s s i b l e f o r these c o b a l t Ions to .exchange w i t h the ©bait i n [_Co(phth) J . Such an exchange *-» r i + + has been observed between Pe ions and [Fefphth)^] (29). A standard r a d i o a c t i v e c o b a l t s o l u t i o n was prepared i n the f o l l o w i n g manner. Approximately 0.2gms. Co^ 0^ were d i s s o l v e d i n HCI and a l i t t l e HNO^• The s o l u t i o n was made up t o approximately 100ml. and CoCL2»6H 20 added t o o b t a i n the d e s i r e d s p e c i f i c a c t i v i t y . Three 2.0ml. samples were measured out, evaporated n e a r l y to dryness t o get r i d of the W0^, d i l u t e d to 10ml., and analysed f o r c o b a l t using«<.-nitroso /4-naphthol. (41) Table X I . Wt. of C o ( C 1 0 H 6 0 2 N ) 3 . 2 H 2 O . Wt. Co. 1. 0.1252 gms. 0.0121 gms. 2 . 0.1170 0.0118 3. 0.1299 0.0120 Ave.- 0.0120 gms. Co/ 2 mis. S o l u t i o n . 0.0060 gms. Co/ 1 ml. S o l u t i o n . 1 p o r t i o n s of the s o l u t i o n were evaporated t o dryness and counted: 2400*57 counts/min. 1 gm. c o b a l t -4*10** counts/min. In order t o study the exchange between Co and [ b o ( p h t h ) 3 J * * a s o l u t i o n was prepared by adding t o a known weight of ortho-phenanthroline s u f f i c i e n t C o C l 2 » 6 H 2 0 t o complex the ortho-phenanthroline and p r o v i d e a Co1"*" i o n c o n c e n t r a t i o n of approximately 0.02M. To t h i s was added 5mls. of standard Co C l g s o l u t i o n , and the s o l u t i o n was d i l u t e d to 50mls. At the end of the d e s i r e d l e n g t h of time 5 mis. o f s o l u t i o n were withdrawn and the \Co(phth) 3" p r e c i p i t a t e d w i t h an ammoniacal s o l u t i o n of CoCCO^H, as {c°(C0)4]2 f P ^ P k t * 1 ^ • time was taken as the time at which the p r e c i p i t a t e formed. The p r e c i p i t a t e was f i l t  e r e d througha G-ooch c r u c i b l e , washed w e l l w i t h water and a l i t t l e a l c o h o l , and d r i e d i n a vacuum. When dry the p r e c i p i t a t e was weighed i n the c r u c i b l e , and then d i s s o l  ved i n acetone, u s u a l l y l e a v i n g a small amount of I n s o l  uble r e s i d u e . A f t e r d r y i n g i n a vacuum the c r u c i b l e was (42) reweighed, g i v i n g the weight e f [Co ( G 0 ) ^ J 2fcotphth)^] i n s o l u t i o n , The s o l u t i o n was d i l u t e d t o 50mls. and 0.4 ml, samples counted. From the weight of p r e c i p i t a t e i n the acetone s o l u t i o n and I t s a c t i v i t y , the a c t i v i t y of the £co(phth ) 3 J was c a l c u l a t e d , and hence the percent exchange, the percent exchange being taken as the percent of c o b a l t which had been t r a n s f e r r e d from the c o b a l t i o n t o the phenanthroline complex. From the c o n c e n t r a t i o n s of Co , Co*"**, and [Co(phth)^ J^in the o r i g i n a l s o l u t i o n , the theor e t i c a l percent exchange at e q u i l i b r i u m was c a l c u l a t e d , u s i n g the f a c t t h a t at e q u i l i b r i u m the r a t i o of a c t i v e t o i n a c t i v e c o b a l t atoms w i l l be the same f o r Co and f o r [co(phth ) 3 ]*T The f o l l o w i n g r e s u l t s were ob t a i n e d : 1. Wt. o-phth.H 20 - 0.594-0 gms, : Wt. C o C l 2 . 6 H 2 0 - 0.3000 gms. 5 mis. Co CI2 s o l n . - 0.0300 gms. Co= 1 .2 10 7 c/m. Wt. of c o b a l t as Co* + - 0.0454 gins. Wt. Co i n Complex - 0.0589 gms. Table X I I . Time. ^Exchange.  1 h r . 44.4 % 2 h r s . 43.2 % 4 h r s . 44.9 %. T h e o r e t i c a l percent exchange at e q u i l i b r i u m - 56.5$ (43) 2. Wt. o-pb.th.H2O - 0.5943 gms. Wt. C o C l 2 . 6 H 2 0 - 0.3459 gms. 5 mis. C o * C l 2 sdn. =. 0 . 0 3 0 0 gms. Co 1.2 10 7 c/m. Wt. c o b a l t as Co"** 0.0568 gms. Wt. c o b a l t In complex 0.0589 gms. Table X I I I . Time. jo Exchange. 2.5 min. 31.5 10 30.9 20 36.9 30 34.5 40 „ 35 .4 T h e o r e t i c a l percent exchange at e q u i l i b r i u m - 50.95$ Prom these r e s u l t s i t can be seen that the c o b a l t seems to exchange v e r y r a p i d l y r e a c h i n g an e q u i l i b r i u m value i n a few minutes. T h i s e q u i l i b r i u m value i s however, c o n s i d e r a b l y lower than the t h e o r e t i c a l value which Is expected. The method used has the disadvantage that the p r e c i p i t a t e of [Co(C0)^l 2 £c°(phth)3| might c a r r y down w i t h i t a c e r t a i n amount of adsorbed Co cl2» Then i f the r a t e of exchange i s slow, the adsorbed C o X C l 2 , which would be expected t o be a constant, would cover up any change i n the percentage exchange, and make I t appear as though an e q u i l i b r i u m had been a t t a i n e d . The s l i g h t upward t r e n d i n the f i g u r e s i n the second set of measurements make i t appear (44) as though t h i s may be the case. In order to a s c e r t a i n whether the observed r e s u l t s are due to a very r a p i d exchange between c o b a l t ions and the c o b a l t i n [ c o ( p h t h ) 3 ] ^ or whether the a c t i v i t y i s merely the r e s u l t of a d s o r p t i o n of a c t i v e c o b a l t c h l o r i d e by the p r e c i p i t a t e , a d i f f e r e n t method of sep- a r a t i n g the Co and LCo(phth) 3J ions was d e v i s e d . C o b a l t forms two i n s o l u b l e hydroxides, c o b a l t o u s hydroxide, Co(0H) 2» and c o b a l t i c hydroxide, 00(011 ) 3 . Since c o b a l t normally has the valence of two, Co(OH)2 Is g e n e r a l l y formed on the a d d i t i o n of a base suoh as sodium hydroxide. I f however the c o b a l t Is f i r s t o x i d i z e d t o a valence of three with an o x i d i z i n g agent such as hydrogen peroxide, c o b a l t i c hydroxide can be p r e c i p i t a t e d , and i s much more i n s o l u b l e than cobaltous hydroxide, having a s o l u b i l i t y i n water of 0.00032 gms./lOO mis. I t should thus be p o s s i b l e to separate Co from L C o ( p h t h ) 3 j by the p r e c i p i t a t i o n of the c o b a l t Ions as c o b a l t i c hydroxide, p r o v i d e d t h a t t h i s method does not a l s o p r e c i p i t a t e some of the c o b a l t from the phenanth- r o l i n e complex. A f t e r f i l t e r i n g o f f the p r e c i p i t a t e of Co(0H) 3, d e t e r m i n a t i o n of the a c t i v i t y of the s o l u t i o n g i v e s the amount of exchange. By running a blank cont a i n i n g c o b a l t ions only, the a c t i v i t y due to c o b a l t ions u n p r e c i p i t a t e d by the hydroxide can be determined and s u b t r a c t e d from the a c t i v i t y of- the s o l u t i o n . (45) To determine whether or not the c o b a l t i n ^CofphtbO^ J can be p r e c i p i t a t e d as c o b a l t i c hydroxide, a s o l u t i o n was made up c o n t a i n i n g enough CoClg and # o-phenanthroline to form the c o b a l t phenanthroline complex and p r o v i d e a very s l i g h t excess of o-phenanthroline. A few drops of 30$ hydrogen peroxide were then added, and the s o l u t i o n made b a s i c w i t h 6N NaOH to a P.H. of about 1 0 . Under these c o n d i t i o n s no p r e c i p i t a t e o f c o b a l t i c hydroxide c o u l d be observed. A s o l u t i o n was prepared c o n t a i n i n g [po(phth ) 3 j ions and a c t i v e c o b a l t (II) c h l o r i d e . To separate the two ions a f t e r the d e s i r e d l e n g t h of time had elapsed, 5 ml. p o r t i o n s of the s o l u t i o n were withdrawn, 3 drops of 30$ H 2 0 2 were added, and 10 drops 6NaOH to b r i n g the P.H. to about 1 0 . The p r e c i p i t a t e of Co(0H)3 was co a g u l a t e d by b r i n g i n g the s o l u t i o n to the b o i l i n g p o i n t , and w a s . f i l t  ered o f f through a double t h i c k n e s s of f i l t e r paper. The p r e c i p i t a t e was washed w i t h about 45. ml. d i s t i l l e d water to b r i n g the volume of the f i l t r a t e to 50 mis. 0 . 3 ml. p o r t i o n s were evaporated to dryness and counted. A blank was prepared c o n t a i n i n g the same amount of a c t i v e c o b a l t (II) c h l o r i d e , but no c o b a l t phenanthroline complex. Co(OH) 0 was p r e c i p i t a t e d under the same c o n d i t i o n s as 3 d e s c r i b e d above and the a c t i v i t y found i n the f i l t r a t e s u b t r a c t e d from the a c t i v i t y obtained i n the exchange measurements. (46) The f o l l o w i n g r e s u l t s were obtained; Wt. of o-phth.H 20 - 0.5897 gms. Wt. of CoCl .6H o - 0.3457 gms. 5 mis. a c t i v e C o C l ^ s o l n . c o n t a i n i n g 0.0211gms. Co » 8.425 10 cts/min. S o l u t i o n d i l u t e d t o 50 mis. Wt. of c o b a l t i n complex - 0.0586 gms. Wt. o f c o b a l t as Co +* - O.O48O gms. Blank - 16*5 cts./min./0.3mls. Ta b l e XIV. Time cts./min./0.3 mis. % Exchange of f i l t r a t e  5 min. 3659 ± 5 1 72.2$ 1 day 3788 2 46 74.6 2 days 3681 &26 72.5 3 days 3830 2 34 75.4 8 days 3693 £ 60 72.6 T h e o r e t i c a l percent exchange at e q u i l i b r i u m - 55.04 These f i g u r e s c o n f i r m the r e s u l t found p r e v i o u s l y , t h a t Co-*4 ions exchange very r a p i d l y w i t h [ c o f p h t h ^ * * r e a c h i n g an e q u i l i b r i u m v a l u e i n a few minutes. The e q u i l i b r i u m value found e x p e r i m e n t a l l y howeveB, Is much higher than the value c a l c u l a t e d from the conc e n t r a t i o n s of the va r i o u s i o n s . T h i s i s probably due t o the f a c t t h at 00(011)3, i n the presence of too (phth) 3 1 * t tends to form a c o l l o i d a l " s o l u t i o n , which i s hard to f i l t e r . ( 4 7 ) Co(OH) 3 l e f t In the f i l t r a t e i n t h i s manner would i n c r e a s e the a c t i v i t y of the f i l t r a t e , making the experimental exchange value too h i g h . (48) Study of the Exchange Between Cobalt Metal and D i c o b a l t  O c tacarbonyl* The exchange between a c t i v e c o b a l t metal and c o b a l t o c t a c a r b o n y l i n a s o l u t i o n of benzene, was s t u d i e d at room temperature. The a c t i v e c o b a l t was prepared i n the f o l l o w i n g manner: 0.0508 gms. o f Co 2 0 3 were d i s s o l v e d i n H2SO4, 10 gms. o f (NH^) 2S04 and 40 mis. cone. NH^OH added, and the s o l u t i o n d i l u t e d to 150 mis. The s o l u t i o n was e l e c t r o l y s e d between pl a t i n u m e l e c t r o d e s u s i n g 1 amp. at 5 v o l t s . The d e p o s i t of c o b a l t was washed w e l l w i t h water, d r i e d and weighed. Wt. of Co de p o s i t - 0.0191 gms. Th i s would c o n t a i n 1.1*10 c/m.\.0.0445 gms.("Co(C0) were d i s s o l v e d i n benzene, g i v i n g a 0.00325M s o l u t i o n . The r a d i o a c t i v e c o b a l t was added, the system evacuated, and allowed t o stand f o r 18 h r s . at room temperature. At the end of t h i s time a good d e a l of the c a r b o n y l had decomposed, forming a p i n k i s h p r e c i p i t a t e . The a c t i v e c o b a l t metal was removed from the s o l u t i o n , the p r e c i p  i t a t e f i l t e r e d o f f , the. s o l u t i o n evaporated t o dryness, and b o t h p r e c i p i t a t e and s o l u t i o n counted. Background - 5 0 1 1 cts./min© S o l u t i o n - 50 i 1 P r e c i p i t a t e - &Z t 2 T h i s I n d i c a t e s no exchange between c o b a l t metal and L C o ( c ° ) 4 ] 2 * (49) IV. D i s c u s s i o n of R e s u l t s , The compound £ Co ( C O ) ^ ^ C C o (P^ith.)was prepared and found to be unstable b o t h i n the dry s t a t e and i n s o l  u t i o n i n v a r i o u s o r g a n i c s o l v e n t s . C o n d u c t i v i t y measure ments i n acetophenone and benzaldehyde i n d i c a t e t h a t the compound has a molar c o n d u c t i v i t y corresponding to t h a t of a s t r o n g e l e c t r o l y t e , i n d i c a t i n g that i t i s a true s a l t of c o b a l t c a r b o n y l h y d r i d e . The r e s u l t s obtained agree w i t h those quoted by p r e v i o u s workers. Transference measurements i n d i c a t e that the t r a n s  f e r e n c e number of the ^Co(CO)^") i o n i s g r e a t e r than that of the |C°(P nth ) 3 j i o n . T h i s i s to be expected, s i n c e the l a t t e r i o n i s probably the l a r g e r , and hence would have a lower i o n i c m o b i l i t y . The p r e c i p i t a t e formed on the cathode d u r i n g the e l e c t r o l y s i s of an acetone s o l u t i o n of \po(CO) j\ 2 (p°(phth) was found to c o n t a i n 3*5$ a c t i v e c o b a l t , whereas w i t h the c o b a l t atom i n £ . 0 0 ( 0 0 ) ^ a c t i v e i h e p r e c i p i t a t e c o n t a i n e d 6.7$ a c t i v e c o b a l t . I f the r e a c t i o n s p o s t u l a t e d are c o r r e c t the p r e c i p i t a t e should be [Co(phth)3l(OH)2> which would c o n t a i n 9»58$ a c t i v e c o b a l t i n the f i r s t case and should be i n a c t i v e In the second case. I t i s p o s s i b l e t h a t the p r e c i p i t a t e c o u l d be a compound c o n t a i n i n g b o t h [ c o(phth ) 3]*and [ c o ( C 0 ) ^ j i n some manner. T h i s does not seem probable however because of the h i g h l y i o n i z e d form of [ c o ( C 0 ) 4 l 2 j c o ( p h t h ) ^ . I t seems l i k e l y , t h e r e -(50) f o r e that the p r e c i p i t a t e c o n t a i n s only the [bo(phth)^J*"*" i o n , and the r e s u l t s can on l y be e x p l a i n e d by exchange of some s o r t between the two c o b a l t atoms. I t has been shown that the two c o b a l t atoms i n C G o ( C 0 ) ^ 2 (jP°(P^th) ^ "J do not exchange at room temperature i n an a c i d s o l u t i o n over a p e r i o d of a few hours. T h i s does not preclu d e t h e i r exchange i n an acetone s o l u t i o n , but i t i s h a r d l y t o be expected t h a t i f such an exchange d i d occur i t would be r a p i d enough to g i v e the r e s u l t s o b t a i n e d . Exchange has been observed however between c o b a l t (II) Ions and [ b o^rith^ J^ions i n s o l u t i o n . T h i s exchange i s v e r y r a p i d and reaches an e q u i l i b r i u m value almost I n s t a n t a n e o u s l y . If, t h e r e f o r e , Co ions were present i n the acetone s o l u t i o n , due to decomposition of £co(C0)^\ , r 1 ** they would exchange w i t h the [Co(phth)-^j i o n s , g i v i n g the r e s u l t s o b t a i n e d . Assuming t h i s to be the case, and that the p r e c i p i t a t e on the cathode i s (bo(phth ) 3](OH) 2 the amount of c o b a l t exchanged at e q u i l i b r i u m , and hence the percent a c t i v e c o b a l t i n the p r e c i p i t a t e can be c a l c u l  a t e d . Por [ c o ( C 0 ) ^ 2 f c o ( p h t h ) 3 ] : In one mole of the compound, 118 gms.COoXln [Co(C0 ) ^ J 2 59 gms. Co i n [ C o ( p h t h ) ^ Then at e q u i l i b r i u m , the r a t i o of a c t i v e t o i n a c t i v e atoms w i l l be the same i n bo t h cases so t h a t : ( 5 1 ) x 5 9 - x - w h e r e x * w t . o f a c t i v e 1 1 8 5 9 c o b a l t t r a n s f e r r e d f r o m C o ( p h t h ) 3 t o C o C C O ) ^ x e 3 9 g m s . T h e { C o ( p h t h ) 3 J t h e r e f o r e n o w c o n t a i n s . . 5 9 - x • = 2 0 g m s . a c t i v e c o b a l t . T h e p e r c e n t a c t i v e c o b a l t i n ( c o t p h t h ^ ] ( 0 H ) 2 Is t h e r e f o r e , 2 0 1 0 0 $ ^ 3 . 2 5 $ 6 1 6 . 2 S i m i l i a r c a l c u l a t i o n s f o r [ c o ( C 0 ) ^ j 2 ^ 0 ( p h t h ) 3 J g i v e f o r t h e w e i g h t o f a c t i v e c o b a l t I n ^ C o ( p h t h ) ^ a t e q u i l  i b r i u m a v a l u e o f 3 9 g m s . , a n d a p e r c e n t a c t i v e c o b a l t o f 6 . 5 $ . T h e s e c a l c u l a t i o n s a s s u m e t h a t a l l t h e c o b a l t i s i n a f o r m i n w h i c h i t c a n e x c h a n g e . I t c a n b e s e e n t h a t t h e s e v a l u e s a g r e e v e r y c l o s e l y w i t h t h o s e o b t a i n e d . e x p e r i m e n t a l l y . P e r c e n t A c t i v e C o b a l t i n ( c o ( p h t h ) 3 j ( 0 H ) 2 . E x p e r i m e n t a l . C a l c u l a t e d . [ c o ( C 0 ) 4 ] 2 [ c o ( p h t h ) 3 ] 3 . 5 7 $ 3 . 2 5 $ [ c o ( C 0 ) ^ 2 ( C o ( p h t h ) 3 j 6 . 7 $ 6 . 5 $ I n t h e p r e s e n c e o f a n e x c h a n g e s u c h a s t h i s i t i s o f c o u r s e i m p o s s i b l e t o o b t a i n t h e c o r r e c t t r a n s f e r e n c e n u m b e r s b y t h e m e t h o d d e s c r i b e d . (52) V. Suggestions f o r F u r t h e r Work* An a n a l y s i s of the p r e c i p i t a t e formed on the cathode d u r i n g the e l e c t r o l y s i s of 100(00)^2£co(phth) 3J should be made, to determine whether or not i t s formula agrees w i t h t h a t p o s t u l a t e d . Because the presence of o-phenanthroline e l i m i n a t e s the normal I o n i c r e a c t i o n s of valence two c o b a l t , t h i s can not be done by any of the u s u a l a n a l y t i c a l methods. HIeber (15) however has d e v i s e d a s u i t a b l e method f o r a n a l  y s i n g the c o b a l t i n [ c o t C O j ^ ^ f c o t p h t h ) ^ ] by h e a t i n g the substance i n a p l a t i n u m c r u c i b l e , decomposing the r e s i d u e w i t h KHSO^, d i s s o l v i n g i t i n water, and p r e c i p i t a t i n g the c o b a l t as the a n t h r a n i l a t e . The p o s s i b i l i t y of exchange between the c o b a l t atoms i n £00(00)4]2 (0°(Phth)2] should be s t u d i e d f u r t h e r , esp e c i a l l y i n s o l u t i o n s of acetone. Exchange may be present, but may not have been s u f f i c i e n t to d e t e c t i n the short time that the compound was i n e x i s t e n c e . (53) B i b l i o g r a p h y . ( 1 ) W. Hieber H. Sc h u l t e n , R. Marin - Z . Anorgan. Chem., 2 4 0 , 2 6 1 ( 1 9 3 9 ) ( 2 ) L. Mond, H. H l r t z , M.D. Cowap - Proc. Chem. S o c , 2 6 , 6 7 ( 1 9 1 0 ) ( 3 ) H. S c h u l t e n - Z . Anorgan. Chem., 2 ^ 3 , 1 4 5 ( 1 9 3 9 ) " (4) W. Hieber, Behrens, F i l t e r - Z . Anorgan. Chem., 2 4 9 , 2 6 ( 1 9 4 2 ) (5) A. Job, A. C a s s a l - Compt. Rend., 1 8 3 , 3 9 2 ( 1 9 2 6 ) ( 6 ) M.P. Schubert - J . Am. Chem. S o c , 55 . , 4 5 6 3 ( 1 9 3 3 ) ( 7 ) G.W. Coleman, A.A. Blanchard - J . Am. Chem. S o c , 5 8 , 2 1 6 0 ( 1 9 3 6 ) ( 8 ) W. Hieber - Z . Elektrochem., 4/3, 2 9 0 ( 1 9 3 7 ) (9) W. Hieber, F. Mtihlbauer, E.A. Ehmann - Ber., 6 5 , 1 0 9 0 ( 1 9 3 2 ) ( 1 0 ) A.A. Blanchard, P. Gilmont - J . Am. Chem. S o c , 6 2 , 1 1 9 2 ( 1 9 4 0 ) ( 1 1 ) A.A. Blanchard, P. Gilmont - Inorganic Syntheses.,;, P. 2 3 8 . ( 1 2 ) G.W. Coleman - Unpublished work. See A.A. Blanchard - Chem. Rev., 2 1 , 1 9 ( 1 9 3 7 ) ( 1 3 ) P« Krumholz, H. S t e t t i n e r - J . Am. Chem. S o c , 7 1 , 3 0 3 5 ( 1 9 4 9 ) (14) W. Hieber, H. S c h u l t e r - Z . Anorgan. Chem., 2 3 2 , 1 7 ( 1 9 3 7 ) (54) W. Hieber, H . S c h u l t e n - Z. Anorgan. Chem., 232, 29(1937) W. Hieber, E. Pack - z. Anorgan. Chem., 263, 83(1938) - W. Hieber, P. L e u t e r t - Ber., 65B, 1090(1932) W. Hieber, P. Spacee - Z. Anorg. Chem., 233, 353(1937) Sidgwick, B a i l e y - Proc. Roy. S o c , A144, 521 (1934) H.M. P o w e l l , R.V.G. Ewens - J . Chem. S o c , 286 (1939) * K.A* Jensen .- Z. Anorgan. Chem., 252, 234(1944) L.O. Brockway, J.S. Anderson. - Tr a n s . Paraday S o c , 33, 1233(1937) W. Hieber, p. L e u t e r t - Z. Anorgan. Chem., 204, 145(1932) W. Hie b e r , - Die C h e m i c , 55., 25(1942) R.V.G. Evans, M.W. L i s t e r - Trans. Paraday S o c , 35, 681(1939) A. Vogel - Q u a n t i t a t i v e Inorganic A n a l y s i s , P. 547 G.: Jones, B.C. Bradshaw - J . Am. Chem. S o c , 55, 1780(1933) E.W. Washburn - J . Am. Chem. S o c - 31, 322(1909) S. Ruben, M.D. Kamen, M. Bauen, P.' Nahinsky - J . Am. Chem. S o c , 6J., 22978(1942) (55) The f o l l o w i n g reviews on the s u b j e c t were a l s o used; (1) Wm. E . Trout J r . - J . Chem. Ed., 1£, A53, 456, 575(1937) 15, 77(1938) (2) A.A. Blanchard - Science, 94_, 311(1941) (3) Smith - Science Progress, 3_5, 283(194?) (4) J»S. Anderson - Quart. Rev., 1,• #A, 331(1948) 

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