Structure of tetra(n-butyl)ammonium tetraiodo-μ,-μ′-diiododiplatinate(II), [(n-C4H9)4N]2[Pt2I6]

The crystal structure of [(n-C₄H₉)₄N]₂[Pt₂I₆] has been determined from X-ray data measured by counter methods. It crystallizes in the monoclinic space groupP2₁/c (C _2h ^-5 , No. 14) with unit cell constantsa=14.457(4),b=14.036(4),c=23.696(5) Å,=101.02(3)°, andD _c =2.30 g cm^–3 forZ=4. Full-matrix least-squares refinement led to a finalR value of 0.049 for 1786 independent observed reflections. The [Pt₂I₆]^2– anion is planar to within 0.07 Å and exhibits an average Pt-I bridging bond length of 2.559(4) Å and average Pt-I terminal distance of 2.571(7) Å. Of the two independent [(n-C₄H₉)₄N]⁺ cations, one approaches a ¯42m-D _2d conformation, the other an approximate ¯4-S₄ conformation.     

Producing μ−d and μ−t in vacuum

After the feasibility of vacuum isolated ^–d production was demonstrated at TRIUMF in 1989, development was begun on a target system that would take advantage of the process to aid in the understanding of the muon catalyzed fusion cycle. Minimal neutron backgrounds, the ability to use silicon detectors, and compatibility with tritium were considered important for a very versatile target system. The advantages which the target gives in isolating CF process will be outlined.     

The solubility of CaMoO4(c) and an aqueous thermodynamic model for Ca2+-MoO 4 2 -ion-interactions

The solubility of powellite [CaMoO₄(c)] was studied in aqueous Na₂MoO₄, CaCl₂ and Ca(NO₃)₂ solutions ranging in concentrations from 1×10^–4M to 1.0M and over equilibration times extending to 36 days. Our experimental data were interpreted using the aqueous ion-interaction model of Pitzer and coworkers. The Ca²⁺–MoO ₄ ^2– ion-interactions were found to be analogous to Ca²⁺–SO ₄ ^2– . The use of Ca²⁺–MoO ₄ ^2– ion-interactions parameters (⁽⁰⁾=0.2, ⁽¹⁾ = 3.1973 and ⁽²⁾) and a logK _sp of –7.93 gave excellent predictions of all of the experimental data. Commonion ternary interaction parameters such as MoO ₄ ^2– –Cl^– or MoO ₄ ^2– –NO ₃ ^– were not required.     

THE EFFECTS OF PHOTOOXIDATION BY PROFLAVINE ON HeLa CELLS—II. DAMAGE TO DNA

Abstract— HeLa cell suspensions, prelabeled with specific [¹⁴C]-nucleosides, were treated with proflavine and irradiated with visible light (400–500 nm). The DNA was isolated from the cells (as well as from the appropriate control cells) and examined for macromolecular and molecular changes. Although the UV absorbance spectrum of DNA from irradiated HeLa cells showed no discernible change, a fluorescence spectrum (excitation/emission: 305/405) indicated a molecular change in the DNA. Isolated DNA samples were hydrolyzed with 90% formic acid and chromatographed. There were no detectable differences between the irradiated and non-irradiated profile (R _f and radioactivity) for both guanine and adenine. However, the chromatograms of thymine and cytosine showed distinct changes. There was a loss of radioactivity in the [¹⁴C]-thymidine labeled samples, while the [¹⁴C]-cytidine labeled samples indicated the formation of a new compound, containing 10% of the radioactivity, running just ahead of cytosine. These data strongly suggest the formation of a new compound resulting from the photooxidation of cytosine when nuclear DNA was sensitized by proflavine.     

The Displacement of Sr from Organic Chelates by Hydroxide, Carbonate, and Calcium in Concentrated Electrolytes

The effects of calcium, hydroxide, and carbonate on the displacement of Sr from four organic chelates: ethylenedinitrilotetraacetic acid (EDTA), N-(2-hydroxyethyl)ethylenedinitrilotriacetic acid (HEDTA) nitrilotriacetic acid (NTA), and iminidiacetic acid (IDA) was studied in solutions with high base and carbonate concentration. Comparison of solutions with and without added chelators allowed the speciation changes in solution to be directly determined. Increases in both carbonate and calcium concentration were effective in displacing Sr from the chelators even under high carbonate concentration. Increases in hydroxide were ineffective in removal of Sr from the chelators, even at base concentrations as high as 6M. Under certain specific conditions, most notably when both CaCO₃(s) and SrCO₃(s) are present in solution, chemical equilibrium constraints result in cancelation of activity coefficient changes for aqueous Sr and Ca organic chelate complexes. Under such conditions the predicted ratios of chelated Ca and Sr become independent of the ionic media and predictive relations using known equilibrium constants give very good representations of the experimental data. These results indicate that manipulation of metal ion displacement reactions during chemical processing of Sr–chelate solutions can result in the displacement of Sr from organic chelators. The implications of such strategies in processing high level waste supernatants stored at Department of Energy (DOE) sites is discussed.     

Synthesis,crystal and molecular structure and spectroscopic studies (i.r., electronic,13C-n.m.r. and Mössbauer) of the perchlorate of nitrosyltetracyanoiron(II)-μ-cyano-pentaamminecobalt(III)trihydrate and its chromium(III) analogue

Summary The two new title compounds have been synthesized and characterized by x-ray crystal structure and spectroscopic measurements. Both compounds are air-stable and isomorphous. The crystal system, space group and Z for both compounds are: hexagonal, p6₁ and 6. Lattice constants for the Co^III and Cr^III complexes are as follows:a = 9.674(3) Å,c = 37.196(6) Å anda = 9.786(3) Å,c = 37.852(6) A, respectively. The molecular structure shows a great distortion in the Fe-C-N-M torsion angle [–46.8(7)° and –51.3(7)°, respectively] which has been interpreted as due to the presence of the NO ligand. The spectral studies confirm the presence of the -cyano ligand by the clear splitting of the (CN) stretching vibration atca. 2200 cm^–1 and the shift of 15–20 nm towards higher frequencies in the first d-d transition of M^III. The¹³C-n.m.r. spectrum of the diamagnetic Co^III complex confirms the presence of the -cyano ligand in solution and, as in the solid phase, the bridging group iscis to the NO of the nitroprusside. The Mössbauer spectra show that the principal axis component of electric field gradient tensor will most likely be directed in the Fe-NO direction (as in the nitroprusside ion) and not towards the CN bridge.