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11.
The infrared and Raman spectra of gaseous and solid (CH3)3 GeNCO and solid (CH3)3GeNCS have been recorded over the frequency range 20–4000 cm?1 . The Raman spectra of the liquids have also been recorded. Assignments of the normal modes have been made on the bases of band types, Raman depolarization values, and characteristic frequencies. Spectral data indicate that (CH3)3 GeNCO is non-linear in all phases and that (CH3)3GeNCS has a linear or quasi-linear heavy atom skeleton in the fluid phases. 相似文献
12.
Philip J. Cox Olga A. Melvin Simon J. Garden James L. Wardell 《Journal of chemical crystallography》1995,25(8):469-475
The title organotin carbohydrate, C31H36O6Sn, has been synthesized and its molecular structure has been determined in solution and in the solid state. NMR, infrared, mass and X-ray crystallographic techniques were used. The chiral molecules crystallize in the monoclinic space group P21 withZ=2. The triphenyltin and carbohydrate moieties are linked by a trans methylene-oxygen-methylene arrangement. The pyranosyl ring adopts a twist-boat conformation and the isopropylidene rings adopt different (half-chair and envelope) forms. Solution and solid-state conformations are similar as only three 13C shift values are greater than 2ppm; the 119Sn value is 12 ppm. 相似文献
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R. L. Lichti K. H. Chow D. W. Cooke S. F. J. Cox E. A. Davis R. C. DuVarney T. L. Estle B. Hitti S. R. Kreitzman R. Macrae C. Schwab A. Singh 《Hyperfine Interactions》1994,86(1):711-716
Longitudinal-field muon-spin depolarization rates in high-purityGe and semiinsulatingGaAs are reported and compared to similar data for intrinsicSi. Depolarization onset temperatures provide a comparison of charge carrier concentrations leading to rapid charge exchange and a shift in the onset, for n-typeGaAs verifies anelectron process. The temperature dependence of the low-field rate constants imply more complicated dynamics inGe than observed earlier inSi. Features near 750K inGaAsTe appear consistent with dissociation of aMu-Te pair.This work was supported by the US National Science Foundation (DMR-8917639 [TLE, BH]), the Science and Engineering Research Council of the UK (EAD, AS, SFJC), the Robert A. Welch Foundation (D-1053 [RLL], and C-1048 [TLE]), and a NATO Collaborative Research Grant (RLL, SFJC, RCD, CS). We wish to thank D.A. Vanderwater of Hewlett Packard for providing theGaAsTe sample. 相似文献
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Philip J. Cox 《Journal of chemical crystallography》1993,23(3):203-208
The molecular structure of the cytotoxic sesquiterpene lactone eupatocunin has been determined by X-ray crystallographic analysis of theo-bromobenzoate derivative. Two structural isomers, arising from hindered rotation, are present within the single crystal. The molecules are disordered (ratio 0.750.25) with the bromine atom occupying alternate ortho positions on the aromatic ring. Molecular mechanics has been used to examine the energies of molecular conformation by torsion angle variation. 相似文献
19.
J.William Suggs S.D. Cox Robert H. Crabtree Jennifer M. Quirk 《Tetrahedron letters》1981,22(4):303-306
The title complex readily hydrogenates a number of hindered steroidal olefin groups from the α face, without reducing ketone carbonyl groups, carbon—halogen bonds or cyclopropane rings. 相似文献
20.
Geng-Shuen Wu I. C. Martinelli C. Dewitt Btanton Richard H. Cox 《Journal of heterocyclic chemistry》1977,14(1):11-17
The synthesis of N-methyl-3-aza[10]paracyclophane is reported which represents the first example of this ring system being formed via an acyloin reaction. This 3-aza[10]paraeyclophane ring system behaves physiochemically inbetween the normal [9]- and [10]paracyclophane ring systems. Reductive desulfurization of N-methyl-3-aza[10]paracyclophane-6-ethylene thioketal in ethanol provides a small amount of the title compound and an unexpected, ring-opened product, N-ethyl-N-methyl-p-heptylphenethylamine. A possible mechanism for the ring-opening process is suggested. 相似文献