and then reappeared and ptxrsisted a t much higher temperatures. As a general rule more extensive carbonizing results in metal ion emission a t higher temperatures. When filaments werc carbonized for 20 min. or longer a t 22OO0, no U + ions wire observed until the tcmperature exceeded about ?300°. Then UC2+ ions were observcd also but a t an intensity factor of 100 below that of the T7+ ions. It seems that metal ions may arise from several parent molecules. It is prot)al)le that they come from uranium metal (low temperature emission) and from one or morc refractory carbides (high temperature emission). Positive identification of UC2+ ions was made by mass determination and by resolution of the two uranium isotopes in the sample. I t is likely that UC and possibly U Z Cexist ~ on the filaments also, even though they were not observed as stable gaseous species.6 The tem erature a t which metal ions are emitted is consistent with t i e known physical properties of the metal and carbides.’ The oxide ions seem to have a variety of parents also. The trioxide may be present on the filament after evaporation of the sample and be lost a t relatively low temperatures. It is formed also from U02 by an air leak. As KO2 is reduced, UO+ ions are formed. In addition, UO+ ions are produced when air is leaked into a source which has been emitting metal ions only. Prolific emission of both L O + and UOz+ions may be obtained by such an air leak. In one experiment UOf ions first appeared. Then UOI+ ions appeared and grew to an intensity one hundred times that of the original metal ions. A t the same time the metal ion beam increased by a factor of five before i t decreased and eventiially disappeared. It is probable that the intense oxide ( 8 ) 11. A. Wilhelm, e t d . , J . Chem. SOC.(Suppl. 2), 5318 (1949). (7) 11. Etberington, Ed., “Suclear Engineering Handbook,” 1st Ed., McGraw-Hi11 Book Co., S e w York, N. Y., 1958.
beams produced by an air leak are associated with the burn ing of the highly reactive uranium carbides. Oxide ions produced in this manner can be observed a t temperatures far below that a t which metal ions can be produced from the same source in the absence of the leak. Preliminary experiments with 0.1 microgram samples of the alpha emitting P 3 suggest that well over WO/o of the sample may be lost beforc the temperature for maximum mrtal ion emission is reached. Apparently, the uranium is lost during reduction before the more refractory carbides are formed. Experiments arc under way to devise procedures to minimize these losses. Multiple filament assemblies will be used to investigate the problem. With a multiple filament it ehould be possible to separate some of the surface effects from the chemical effects. For example, the effect of the carbonizing procedure on the work function of the surf:ace is unknon~ibut is susceptible to study by the multiple filament technique.
Conclusions Single filament ion sources of tungsten or rhenium will not produce uranium metal ions in the absence of reducing agents other than the filament metals. Deposition of carbon before, during, or after deposition of the sample will ensure subsequent production of metal ions to the exclusion of oxide ions uiiless the pressure is high. It is probable that the success of single filament sources in the analysis of uranium as metal ions is due to the forination of refractory carbides which decompose at high temperatures.
POLAROGRAPHY OF SOME AIETAI, COhIPLEXES WITII TltIETHYLENETETR.~iCIISE:lISE BY E. JACOBSEN A X D K. SCHR$DER Ihpartment of Chemistry, Universzty of Oslo, Blindern, .Torway Receiaed August 17, 1861
The complexcs of cadmium, copper, lead, zinc, nickel and cobdt with triethylenetctrarnine have bwn sitmlird by means any of the dropping mercury electrode. The cadmium, copper and lead complex are reversibly redurcbd to the :imalgam :LI concentration of the reagent. In alkaline medium the divalent cobalt complex is emily oxidized by air to a red-colored trivalent cobalt complex. The nickel, zinc and trivalent cobalt complex showed an irreversible rcduction at the I1.M.IC. The half-wave potentials and the diffusion current constants of the various complexes are given.
Introduction Triethyleiietet~ramir~e (abbreviated “trien”) forms stable complexes with certain metals. The composition and stability of the complexes have been determined by poterit,iomet.ric titrat,ion. The cadrnum complex also has been studied by means of t’hc dropping mercury electrode by Douglas, ct n1.3 They clairn t,hat, the complex is irreversibly reduced at t,rien concentrations less than 0.01 ;If. More recently t,he polarography of thc copper complex has been thoroughly investigated by Joriassen and c o - ~ o r k e r s . ~ I-Iit,hert,o,the polarographic behavior of the complexes formed with ot,her metals has not been invest’igated. The present paper is an ext.ensive study of the polarography of the cadmium, l a d , (1) G. Scbwarzenbach, Helo. China. Acto, 33, 974 (1950). (2) C. N. Reilley and R. W. Schmid, J . Elisha Mitchell SOC.,73, 279
(1957). (3) B. E. Douglaa, H. A. Laitinen and J . C. Bailar, SOC., l a , 2484 (1950).
J. A m . Chem.
(4) IT. B. Jonassen, J. A. Bertrand, F. R. Groves and R. I. Stewns, ibid., 79, 4279 (1957).
copper, zinc, nickel mid cobalt complcxes formed with trien. Experimental Materials---The technical grade tric,thSlenctetramin~, obtained from Fluka A. G., Sxitzerland, was purified as described by Reilley and Sehmid.2 The remaining chemicals were reagent grade and used without further purification. Approximately 0.1 M stock solutions of the metal salts were prepared by dissolving 0.1 male of the corresponding salt in redistilled water and diluting to one litrr. The stock solutions werr standardmed by complexomctric titration with EDTA. Standard solutions of trien Rwe prepared and standardized following the procedure given by Reilley and Sheldon.6 Five-trnths molar phosphate buffer was used a8 supporting electrolyte. The buffrr was prepared by adding potassium hydroxide to phosphoric acid, and its pH meaeured m t h a p€I metrr. In order to avoid precipitation of metal phosphates, 1 3.l ammonia buffer was uscd as indiffcrent electrolyte for the lead, zinc and nickel complexes. The pII of the electrolyte was adjusted to the desired value by adding hydrochloric acid to the ammonia solution. Triton X-100, abtained from Rohm and IIaas Co., Philadelphia, was found to be effrctivc as maximum suppressor. Apparatus and Technique.-Polarograms were recorded (3) C . X. Reilloy and &I. 1’. Sheldon, Talanta, 1, 127 (1958)
0.0
0.8
q 0.7 r&
2 d
1 0.6
0.5
0.4
6
7
8
9
10
I1
12
13
PH. Fig. I.-Variat,ion of half-wave potentials of leud (CWVO 1) and cadmium (curve 2 ) cnmplexes of trien with pH of the
solution.
tmllod. The diffjision curient of the metal cornplexes in solutions rw1tflining rscrss ,reagent was mcasured aiid found to be proportional to thc conccntmtion of the correapoiiding metal. The ddfusion ourront constmts for m l t t t ions contaitling 0 05 -2 mrnoles of inetul coinplelx iLritl cx(:rss ro:igcnt worc 2 3.18 and 2.90 lur the cudmiuin, lcud arid coupor complcsrs, rcspcctivel:. 111contrast t u the rrtdts ohtnincld by Doiikhs, cl ~ 2 . ~thr 8 r d u c t ion of the c:tdmium aortiplcx W ~ L A fourid 1o I)(: rrvrrPihlc at, all c(mceiitratioris uf the cornplexiiig a ~ e u ~'I'he , wiigriit, ilsrd in thc abovc invost igut,ion waq hon el er, not pnrifitd a~idWUB probably cont,an$nntcd mit,h othcr polyaididea. Thus, thc a p p ~e116 i ineversiblo WL~VCB atj low trim cuiiccnt8r:itions rcportcd by r h u g l a ~(dope of log plot -0.03.l) corisrqiirntly may be dtie to two or mnrc poIyairiirio coniplcxcs bring rcdiiced at skiiost the mmr potlcntial. At higher cmocritrti-. tions of the rcagcint howrvcr, the roncetitration of tho polyamine foriniiig the most, st:ible complrx with cadniiurn was grrnt cnoiigli to coiiiplex all thc; mt4il ions preseut, giving oxio rcvcrsihlc wave. 'l'he cornplex coiict ant reported l)y 1higl:iy pFC, = 13.9, also indimtcs that his reageill TVLN coriluminatcd with other polytunitir~. Thc complex constaiits detrrmined by potent iomrtric titration, 11sing purified polytmiuc sohitions and the same ionic strriigth :ISDoiiglas, :irr pK, = 10.8arid 14.0 for the tricii'.2 and tct rapt hylcne pent aminr cnmp1cxesJ6 rclspectively. The data ohtairicd for the copper c*omplex are iii agrccment with t he work published hy Jonas(6) C X Rrilley and J. (1058).
TI. ~Iolloway,J. Am. Them S o c 80, 2917
The nickel and zinc complexe~with Wen shnwrtl TABm I irreversildr rcdrrcion. T h o plot, of log i/(& c) I ~ R I J R T ~C%RRI]NT N ~ U N E T A N ~or I ~ TRrvnr,rNT COnALT r l vas tho pntrritiril w i s riot ti straight liue. A mixxil w r a ~CnMrrnx mum on tho riickcl wave was ol11.v suppressed in t h o 3.00 mmolw of tiirri in 0 5 d f phosphtlto Luffei, $1 8 1 pr.ese1ic.r of 0.0080/0 Triton X-100. Thc lidf-J\ :4ve 0.008% Trilorl Y-l (IO itddcd ~ L Rmuxiilium a u p p e w r -El I potentinls of i m h cwnplcxcs were sbifted to mort n,, inmolor v8.8 &IWL. td/Cm"at"o ricyativc vnlues with increasing concentratinn of the MI
-
~
reagent. IJPcailse of the irrcvarsit)lt-! rcductiou, only R fPw polurograms WOIO rccorded. I n soht h s coIi1,aiiiing 4 rrirnulrs of t r i m t>hchfilf-wnvc p u terillats of thc n r t k d nnd a h c comglcxos wcre - I .20 nnd - 1 38 volts 08. S.C.E., respectivrly. The divalent cobalt trien complex is not rcdnced a t Lhe dropping mcrciiry rl~ctmdc. In ulkalrrie medium, how(lvcr, an anodiu wave due t o oxidation of tlie cvniplex wa~sohvrvcd Expsrimcn ts showed that in dknline mcdium thc divalout co~nplcx is msily oxidized by air t u +: red-colnrcd complox. Polarugrarns uf partly oxidized cobalt, complex showed both an anodic rind n cathodic wave. When hubbling air or oxygen followed by pure nitrogen through thc cell, the diffusion current of the anodic wave dwreaspd and that of the cathodic wave increasrd, nnd after about, fivc ~ninutesbubb!ing wit,h nir only the cathodic wave \vas oh,scrvcd on the poluogram, indicating thnt, thc oxidation was complctc The catkudlc wave of thc cobalt, nomplcx proparrd by oxidfitinn with air was ill-delirred and n, maximum oii the curve was only supprcssed in tho
m
t
0 0501 * 1008 604 1.00s
0.41 42 I
0 17U 0 330
1,62
43
1.58
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45
3
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I
presence of 0 008% Triton X-100 VI 0005% gelatin. The plot of log i/(& 1) us. the potcritial docs not yield a stiarght line, indicating an irrovcrailrle reduction. Tho diffusiou curieiit constant for tha cathodic wave ('l'ablc I) indicritcs, howover, a one-olectron reduction from t hc trivuleu t to the divalent state Tho half-wave potentid of the cathodic wlnvc of the trivalent complex is shifted to mom ncgative values with increasing yli, the shift being about 0.06 volt/pH unit. The trivalent complex is easily prepared. It is stablc against reducing agents (ie., ferrous iron, sulfite, ctc.) and the reduction W L ~ Vis~ well separated from the wnvcs of nickel, lead and cdmium. BCCRIIR~ of the drawnvut wave, nnd tho lack of a suitable plateau for mcnsuring the difIuuon curieiit, the trien complcx is, however, not euit,nblc for the p a n t itative determiriat~or~ of cobalt in the prcsence of other mctds.
-
Introduction aro in every case higher than the appenrmro potcnWc have determined the mass spectral cracking tial reported by Bisscl4 for ions of the same rxiabs, patterns and the appearance potentials of the with the exception of the parent-molecule ion8 in principal ions from the four- and five-membered both molecules. In many instances the differences saturated heterocyclic compounds containing nitro- exceed one electron volt and in certain cases the gen, oxygen and sulfur. A comparison is made of difference in the observed appearance potentials is the various processes and calculated heats of forma- as great as four electron volts. In many instances tion obtained in this study with those obtained in the postulated processes,b using the appearance previous studies of ethylene oxide and propylene potentials reported by Hissel to account for the oxide2 and ethylenimine and ethylene sulfide.3 various ions, require significant rearrangement of Appearance potentials reported in this paper for the neutral products in order to obtain AHr+(ion) various ions from tetrahydrofuran and pyrrolidine (2) E. J. Gallegos and R. W. Kiser, J . Am. CAem. Soc.. 83, 773 (1) This work waa supported in part b y the U. 9. Atomic Energy Commission, under Contrnct No. AT(ll-1)-751 with Kansaa State University. -4 portion of a dissertation presented by E. J. Gallegos to the Graduate School of Eanaas State University in partial f u l f i l r ment of the requirements for the degree of Doctor of Philoaophy in Chemistry.
(1901). (3) E. J. Galleg08 and R. 'vy. Kiser, J . Phys. Chem., 66, 1177 (1961). (4) J. Hiaael. Bull. aoc. r o ~ sci. . Lidpe, 21, 457 (1952). (5) F. H. Field and J. L. Franklin. "Electron Impact Phenomena
and the Properties of Gaseous Ions." Academic Press, Ino., New York, 3'.Y 1957.
