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Describes a method for producing computer-generated images that show the buildup of electron density at any position within a molecular structure.

A series of monoiodoborane adducts LBH 2 I (L = N(CH 3 ) 3 pyridine, 3-methylpyridine, 4-methylpyridine or (C 6 H 5 ) 3 P) has been prepared. Ideally, the addition of suitable amines, phosphines or trimethylarsine to a benzene solution of these adducts would be expected to yield boronium salts containing two different donors coordinated to a central boron atom. These salts, of the general formula LL′BH 2 I, were formed in several instances (L′ = (CH 3 ) 3 P, (C 6 H 5 ) 3 P, (CH 3 ) 3 N). Six previously unreported boronium cations have been characterized. The iodide salts of these boronium cations may be easily converted to their hexafluorophosphate analogs except for the large ligands such as (C 6 H 5 ) 3 P or 3-methylpyridine. In contrast, trimethylarsine reacted with 4-MepyBH 2 I in benzene to give 4-MepyH + I − and [(CH 3 ) 3 AsI] + I − . The proton and boron NMR spectra of all species were investigated when experimentally feasible.

The adducts of BI3 and BBr3 with various tertiary phosphines and their chalcogenide derivatives are described. The proton and boron-11 NMR spectra of many of these compounds are reported for the first time. Although the methyl proton-phosphorus-31 coupling constants are nearly identical in the (CH3)3PBX3 (X = F, Cl, Br, I) series, the boron-phosphorus coupling constant, JBP, is anomalously low for (CH3)3PBI3 (116 Hz) relative to other members of the series. The phosphine adducts of BBr3 and BI3 are white, air and water insensitive solids, whereas the phosphine chalcogenide adducts are quite moisture sensitive. The BI3 adducts with phosphine chalcogenides lose iodine fairly readily to form intractable material.

The addition of an equivalent of Cl 2 , Br 2 or I 2 to a solution of Na[H 3 BCN] in glyme (1,2-dimethoxyethane) yields the cyanoborane cyclic oiligomers previously reported. The addition of an excess of a Lewis base (e.g. a pyridine, a tertiary amine or a tertiary phosphine) to the cyanoborane yields a cyanoborane adduct, LBH 2 CN. The addition of an excess of chlorine yields a solution believed to contain [glyme]-BH 2 CN. This solution reacts slowly with Lewis bases (L) to yield LBH 2 CN, and small amounts of chlorinated cyanoborane adducts. The proportion of chlorinated products relative to LBH 2 CN increases as the amount of moisture in the reaction mixture increases and as the base strength of L is reduced. The chlorination of LBH 2 CN in moist benzene yields LBCl 2 CN as the principal product when L is pyridine, while a complex misture is obtained when L = (C 2 H 5 ) 3 N.

A method is described for determining total platinum in tissues of animals receiving cisplatin. The method is based on total combustion of the tissue, leaving a platinum residue devoid of organic material that can be dissolved in aqua regia and analyzed by carbon-rod furnace atomic absorption spectrophotometry. Combustion eliminates matrix effects in final read-out, providing a means for precisely and reproducibly analyzing a variety of tissues. Platinum levels of 200 ng/0.5 g of sample can readily be analyzed with recoveries from all tissues approaching 100%. The validity of the method is demonstrated by giving rats intravenous doses of cisplatin and subsequently measuring tissue levels of platinum.

SUMMARY: Saccharomyces rouxii cells were maintained on yeast extract/neopeptone/glucose medium (YNG). Experimental medium was depleted of endogenous metal ions by repeated passage of YNG over a chelating ion-exchange resin. This treatment did not compromise the glucose or vitamin content but provided a basal medium to which essential salts could be added in defined concentrations. Accordingly it was possible to demonstrate growth requirements by this yeast species for K+, Mg2+, Zn2+ and Fe3+. Na+ would not replace K+. Additions of 1.0 μ;M-Ca2+, NH4+ and Na+, or 0.1 μ;M-Ni2+, Sn2+, Al3+, Co2+ or Cr3+ to a minimal, reconstituted medium were without effect. Cu2+ and Mn2+ additions were not required for growth but, like Mg2+, Zn2+ and Fe3+, they positively affected the biosynthesis of periplasmic acid phosphatase. Cells from iron-depleted medium had only 1 unit (g dry wt)-1 of native acid phosphatase activity although this could be stimulated 10-fold by addition of FeCl3 to washed cell suspensions before enzyme assay. Additions of 10-60 μ;M-FeCl3 to untreated YNG medium progressively increased the concentration of acid phosphatase after 3 d of culture to an upper value of 75 units (g dry wt)-1, and also increased the amount secreted into the growth medium. While unfortified YNG supported cells with only 28% of their acid phosphatase expressed (the bulk being subject to activation by Fe3+ in the assay medium) the cells from YNG fortified with 60 μ;M-FeCl3 displayed fully activated acid phosphatase. Cells from Mg2+-depleted medium exhibited bizarre, elongated cell shapes and those from Zn2+-deficient medium appeared somewhat angular by light microscopy. Fe3+-deficient cells had apparently normal morphology.

The reaction of trimethylgallium or trimethylindium with 2,3-dicarba-nido-hexaborane(8) yields the closed polyhedral species 1-CH3GaC2B4H6 and 1-CH3InC2B4H6, respectively, in which the metal atom in each case forms one apex of a pentagonal bipyramidal cage. These carboranes have been structurally characterized by boron-11 and proton NMR, mass spectra, and infrared spectra, and by a single crystal X-ray diffraction study of the gallium compound. The X-ray results have disclosed two distinctive features: The gallium atom is closer to the boron atoms than to the carbon atoms in the five-membered equatorial ring; The Ga-CH3 axis is tilted by 23 deg with respect to the perpendicular to the equatorial plane. These findings are interpreted in terms of a qualitative molecular orbital model. The gallium and indium compounds are thermally stable to at least 100C but pyrolysis at high temperatures generates 2,3-C2B4H8. Bromine attacks both metallocarboranes at room temperature, destroying the cage structure and forming the dimer of (CH3)2GaBr and, presumably, the indium analog respectively. (Author)

A series of monohalo- and monopseudohalo-broane adducts LBH 2 X, (L = pyridine, (CH 3 ) 3 N, (CH 3 ) 3 P; X = F, Cl, Br, I, NCS, NCSe) has been prepared and characterized. A correlation was made between the boron-hydrogen coupling constant ( J BH ), the electronegativity of X ( E x ) and the estimated B-X bond distance ( D x ). For L = (CH 3 ) 3 N, J BH = 3·336 E x + 36·426 D x + 47·233, while for L = pyridine, J BH = 34·583 E x + 18·116 D x − 10·328. There was negligible change in J BH in the (CH 3 ) 3 PBH 2 X series.

The new compound tris(trifluoromethylthio)borane, (CF3S)3B, has been prepared by interaction of BBr3 and Hg(SCF3)2 in hydrocarbon solvent. The thioborane is a fairly volatile liquid which decomposes slowly at room temperature yielding BF3 and SCF2. Due to the enhanced Lewis acidity of B(SCF3)3 relative to its proton analog, reaction of the compound with excess trimethylamine gives a white 1:1 adduct whereas B(SCH3)3 does not. The new adduct decomposes in the solid state or in solution to yield (CH3)3NBF3 and a brown-yellow solid material.

The following new compounds containing perfluoroalkyl-tellurium linkages have been synthesized: CH3TeCF3, (CF3)2Te, CH3TeC2F5, (C2F5)2Te. These preparations were brought about by the photochemical interaction of (CH3)2Te and an appropriate perfluoroalkyl iodide in a vycor tube at 310 nm wavelength. The resulting mixture of tellurides, RfTeCH3 and (Rf)2Te in which Rf = CF3 or C2F5, cannot be separated by trap-to-trap distillation, but the relative amounts of each product were determined by 19F NMR spectroscopy. The clear yellow tellurides are air stable, but yield either CF3H or C2F5H on basic hydrolysis. No reaction was noted with CH3Cl up to 80°, but at 215° a mixture of CH3TeCF3 and (CF3)2Te interacted with benzyl chloride to give C6H5CH2CF3 in a 3·4 cent yield.

New 1 : 1 adducts of BBr3 and BI3 with (CH3)3As and (CH3)3Sb are reported. The (CH3)3As adducts are stable indefinitely at room temperature under an inert atmosphere while the (CH3)3Sb compounds slowly decompose at that temperature to form (CH3)3SbX2 (X = Br, I). Boron-11 and proton NMR data suggest that these species may exist as ions in chloroform solution.