Lead solid-state spectra

The peptide cvclo(Glv-Pro-GlvK presents a quite different situation. The analysis of its NMR spectrum leads to the conclusion that it adopts a Cp-symmetric conformation in solution, at least on NMR timescales. The solution NMR spectrum (Figure 2B) shows the minimum number of resonances expected (one per carbon in the repeating trlpeptlde unit). By contrast, in the solid-state spectrum there Is clear indication of asymmetry since there are two Pro Cg resonances in Figure 2A, X-ray diffraction analysis has revealed an asymmetric molecular conformation for the crystalline peptide (17), with two different types of 3-turns, only one of which is intramolecularly hydrogen-bonded. Analysis of the solid state isotropic chemical shifts in terms of local conformation yields a picture of the molecule which is consistent with the X-ray data,... 

The reaction with PPh2CCH leads to the formation of [Au(QF5)(PPh2CCH)[ [53] whose P H NMR spectrum shows a singlet at 17.2ppm, in the H NMR spectrum the resonance of the C = CH proton is observed at 3.46 ppm. The IR spectrum shows, besides the pentafluorophenyl absorptions, a band at 3271 cm due to the V(Csch) and another absorption at 2056 cm for the asymmetric C = C stretch. The structure of this complex was studiedby X-ray diffraction, the Au(I) atom is an almost linearly coordinated and the Au—C and Au—P distances are in the range of the values found for similar complexes. The excitation and the emission data in the solid state at 77 K are 331 and 445 nm. 

The electrides. Following many experimental difficulties, Dye and coworkers were able to demonstrate that reaction of 18-crown-6 with caesium in a 1 2 ratio (under specified conditions) leads to isolation of shiny, black crystals of a product of composition Cs+(18-crown-6)2 (El-laboudy, Dye Smith, 1983 Dye Ellaboudy, 1984). The solid-state 133Cs nmr spectrum, the esr spectrum, and the magnetic susceptibility of this product all indicated that it was of type Cs+(l8-crown-6).e" that is, a crystalline electride in which the anion is a single electron. In overall terms, this exotic class of compound may be considered to lie on the border between metals and non-metals. 

The intermediate cyclooctene complex appears to be more reactive with respect to CS coordination and more sensitive to oxidation when the arene ring bears electron-withdrawing groups (e.g., C02CH3). Dicarbonyl(methyl rj6-benzoate)-thiocarbonyl)chromium is air stable in the solid state and reasonably stable in solution.9 The infrared spectrum exhibits metal carbonyl absorptions at 1980 and 1935 cm"1 and a metal thiocarbonyl stretch at 1215 cm"1 (Nujol) (these occur at 1978, 1932, and 1912 cm"1 in CH2C12 solution).10 Irradiation of the compound in the presence of phosphite or phosphine leads to slow substitution of CO by these ligands, whereas the CS ligand remains inert to substitution. The crystal structure has been published."... 

Photolysis of G + leads to the formation of sugar radicals (Adhikary et al. 2005). Product studies from solid state irradiation of Thd are also available (Gromova et al. 1999). As discussed above, the Thd radical cation is expected to deproton-ate at N(3) and at methyl, and the ensuing structural elements indeed dominate the product spectrum parts of which is shown below. 

The high resolution solid-state 13C NMR spectrum of the HMDA network observed at 80 °C leads to separate lines for the various aliphatic carbons DGEBA methyl carbons, HMDA methylene carbon in the p or y position with respect to the nitrogen atom, CH2 (of the hydroxypropyl ether) directly bonded to the nitrogen, and the CHOH - CH2 - O unit. For the aromatic... 

The absorption spectrum of the gold-lead complex shows two bands at 290 nm (e = 28598 M-1cm-1) and 385 nm (e = 7626 M-1cm-1), while the emission spectrum in the solid state shows only one band at 752 nm at room temperature. It was assigned to a transition between orbitals that appear as a result of the gold-lead interaction. Thus Fenske-Hall molecular orbital calculations indicated that the HOMO is constituted from the 6pz orbital of gold and 6s orbital of lead and the LUMO is entirely constituted from the 6pz orbitals of these atoms. 

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