PHILIPS. GENTILEAND LAWRENCE H. TALLEY
4296
[ C O N T R I B U T I O S FROM T H E N A T I O S A L
LEADCOMPANY
VOl. 79
O F OHIO CHEMICAL DEPARTMENT]
Spectrophotometric Studies of Uranyl-Urea, -Thiourea and -Guanidine Systems in Absolute Ethyl Alcohol1 HI-PHILIPs. GENTILEAND LAWRENCE H. 'rhLLEY RECEIVED APRIL 26, 1957 .Inalpis of absorption spectra and continuous variation studies have been employed to determine t h e stoichiometry of complexes present in uranyl-urea, -thiourea and -guanidine systems in absolute ethyl alcohol. Evidence is presented to show t h a t only one complex is formed with each of the ligands T h e urea and thiourea complexes were found t o exist in a 1 . 2 (uranium/organic base) mole ratio However, t h e guanidine complex exhibited a stoichiometry of 1: 1. I n addition, isolation of the compound U0*(N0,1a,[CO(~H2)1]2 from alcoholic solution supports the interpretation of the spectral measurements made with t h e urea system.
It had previously been reported2that no evidence of compound formation was observed a t room temperature when attempts were made to prepare coordination compounds of uranyl nitrate with various organic ligands in alcoholic solutions. The complexirig agents cited were urea, thiourea, guanidine, nitrilotriacetic acid and ethylenediaminetetraacetic acid. In the course of some studies conducted in our laboratories, evidence was obtained for uranyl compound formation with urea, thiourea and guanidine, a summary of which is presented in this paper.
Experimental Materials.--Uranyl nitrate dill>-drate \\-as obtaiuetl by vacuum drying the hexahydrate (Baker and Aldainson, X.C.S.) over sulfuric acid. The urea (American Cyanamid Coinpan>-), thiourea (Eastinan Kodak Company), guanidine (Eastman Kodak Company) and the absolute alcohol (U. S. Industrial Chemical Company, Reagent Grade, 17. S. P.) were used without further purification.
urea, thiourea and guanidine were prepared and arbitrarilv allowed t o stand 24 hours in t h e dark prior t o making nieasurements. The instability of the solutions toward light necessitated this precaution. Initial spectral transmission curves were obtained with a model DK-2 Beckniaii spectrophotonieter while subsequent studies were made with a model D E Beckman spectrophotometer using Cores cells of 10 mtn. light path. Diureadioxouranium(V1) Nitrate.--To 60 ml. of a 4 &I dcoholic solution of uranyl nitrate dihydrate, urea (19.7 g.) \\-as added in small increments. A finely divided yellow precipitate %ils obtained which was filtered and air-dried. This coinpound melted a t 203-205" a n d x a s extremely waterSolulJle. z.ilZU/. CdlCd. for UOn(SOs)i. [CO(SHz)z!r!: 46.30; S,16.34; urea, 23.36. Found: U, 46.07; 1,15.83; urea, 22.51. In a n analogous mariner, the addition of thiourea t o a n :tlcoholic solution of uranyl nitrate dihydrate resulted in the formation of a deep red-colored solution showing a reaction had taken place. However, a11 efforts t o isolate a uranylthiourea complex mere unsuccessful.
u,
I
I I
-1
200 -
I
1
>
-
0.2 ' 0.1
i
L
0'
