Proton magnetic shielding and susceptibility effects in single crystals of ferrocene

The proton NMR in single crystals of ferrocene has been studied by multiple pulse techniques at room temperature. In crystals of natural shape with plane faces the angular dependence of the resonance frequency due to the anisotropy of the shielding and due to the bulk susceptibility was found to be of about equal size, making analysis of the data practically impossible. By using a single crystal sphere the shape dependent part of the susceptibility contribution could be eliminated. In addition, the resolution obtained by the multiple pulse technique is considerably higher for spheres than for non-spherical crystals. As the ferrocene molecules rotate rapidly about their fivefold axes at room temperature, the shielding tensor σ must be axially symmetric. Having this in mind, the data could be analyzed to yield both the shielding tensor with Δσ = σ₆ - σ_⊥ = ?6.5 ± 0.1 ppm, σ_iso = ?4.2 ± 0.5 ppm from a spherical sample of TMS and the anisotropy of the susceptibility Δ _x = 30 × 10^?6 cgs units.     

Vibrational and lifetime line broadenings in ESCA

The line profile of the narrow, symmetric 1s line from neon, recorded with the new ESCA instrument with X-ray monochromatization, is analyzed. The natural linewidth of this line is found to be 0.23 ± 0.02 eV, in good agreement with theoretical calculations of the oscillator strengths for Auger transitions and X-ray emission. Spectra from molecules show frequently asymmetric core electron lines under high resolution. This rules out previous explanations based on a chemical influence on the natural lifetime. Contrary to earlier assumptions, vibrational excitations are shown to be important in core electron spectra. For methane, the vibrational energy spacing is large enough to allow the vibrational lines to be partly resolved. Recent results from accurate PNO CI calculations on methane agree well with the experimental findings. The Franck-Condon transitions in the C1s and N1s lines from CO and N₂ are shown to be well described in the harmonic approximation and approximating the potential curves of the highly excited core hole states with the potential curve for the ground state of NO⁺, X¹ Σ⁺. Knowledge of vibrational excitations in core electron spectra is shown to be valuable in the analysis of high resolution X-ray emission spectra of free molecules.     

Anionische Nickel-Pseudohalogenid-Komplexe der Typen [Ni{N(CN)2}3]− und [Ni{N(CN)2}2(NCS)2]2−

Anionie Nickel Pseudohalide Complexes of the Types [Ni{N(CN)₂}₃]^? and [Ni{N(CN)₂}₂(NCS)₂]^2? The preparation of a new type of anionic pseudohalide complexes of nickel [Ni{N(CN)₂}₃]^? and of mixed thiocyanate-dicyanamide complexes [Ni{N(CN)₂}₂(NCS)₂]^2? is reported. The structures of the complexes are discussed on the basis of IR- and magnetic measurements. The new compounds are representing polymer octahedral complexes with a bridging function of the dicyanamide ligands.     

Phosphor(III)- Thiohalogenide: SP?F und SP?Br. Massenspektrometrische Untersuchungen

Phosphorus(III) Thiohalides: Sd?P? F and S?P? Br. Mass Spectrometric Investigations The compounds S?P? F and S?P? Br are formed by reaction of P(S)FBr₂ and P(S)Br₃, respectively, with silver at temperatures of about 800 K. S?P? Br is also formed by pyrolysis of P(S)Br₃ at temperatures above 298 K. Mass spectrometric equilibrium measurements lead to the heat of formation of S?P? F: ΔH°₂₉₈(SPFg) = ?260.8 kJ/mol.     

Thermal properties of flame retardant viscose fibers

This paper discusses the problem of the thermal properties of flame retarding additives based on phosphazene derivatives and of the commercial agents TomflamB, FlammexT23P and StockhausenW-20949, as well as of flame resistant viscose fibers containing the above agents. Results of this investigation showed the action of FlammexT23P, StockhausenW-20949 and phosphazene derivatives at lower temperature. TomflamB acted within a much wider range of temperatures. The flame retardant additives applied to viscose fibers change the thermal properties of the fiber material.     

Molten lithium carbonate—sodium carbonate—potassium carbonate eutectic: The reaction of ten main group acidic oxides and oxyanions

The reactions of ten main group acidic oxides and oxyanions with molten alkali metal carbonate eutectics have been studied by thermogravimetry. Products have been identified by IR and Raman spectroscopy and stoichiometries suggested for the several reactions as oxide is progressively incorporated. Ultimately the tetrahedral ortho-oxyanion was formed except with the less acidic oxides (As₂O₃, Sb₂O₃, SiO₂). Sulphite was partially oxidised by the carbon dioxide atmosphere to sulphate.     

Thermal analysis and synthesis of pentazinc hexahydroxide dicarbonate: Investigations by thermogravimetry,thermo molecular beam analysis and x-ray measurements

A combination of thermobalance and X-ray camera is described which allows simultaneous thermogravimetric (TG) and X-ray measurements under high vacuum. During these measurements the sample is positioned in the sample holder of the camera in the usual fashion and is X-raved while the temperature is varied. The molecular beam of the gaseous decomposition products flows through a connecting tube which acts as a molecular beam former between camera and thermobalance. The molecular beam is directed towards the empty balance pan. The orifice through which the beam exits as well as the pan have special shapes that allow transfer of the angular momentum of the decomposition beam to the balance. The exerted force is a function of time and corresponds to the first derivative of the TG curve. i.e. to the DTG curve. The integrated curve is directly proportional to the change in mass of the probe. A quantitative evaluation is possible if the molecular composition of the beam is known. The calibration of the molecular beam and the evaluation of the measurements will be discussed. The results show that simultaneous detection of X-ray scattering and indirect TG curves allows a better interpretation of decomposition reactions.An additional investigation shows that thermal synthesis of chemical com- pounds can also be studied by thermogravimetry. Based on the same compound as described in the analysis. the pyrosynthesis is demonstrated. The special instrumentation and the test conditions are discussed.     

On [Na(POCl3)4]+ Complex Ion Formation: Conductivity,Raman, and NMR studies in the system phosphoryl chloride–sodium tetrachloro aluminate and related compounds

The system POCl₃–NaAlCl₄ was investigated by measuring the conductivity and the Raman and NMR spectra (²⁷Al, ²³Na and ³¹P) as a function of the mol fraction x of NaAlCl₄ in POCl₃. Additionally, Raman spectra of POCl₃ solutions of NaFeCl₄, LiAlCl₄, LiFeCl₄, and KAlCl₄ were recorded. In solutions containing Li⁺ or Na⁺ ions a liquid to solid (or jelly) phase transition was observed under certain conditions, dependent on salt concentration and temperature. Observed changes in the Raman spectra of the electrolyte solutions in comparison to the pure solvent POCl₃ demonstrate the existence of interactions. Clearly, the POCl₃ eigenfrequencies and hence the molecules are pertubed. The formation of [M(POCl₃)₄]⁺ complexes (M = Li, Na) can be deduced from the Raman measurements. NMR investigations support this conclusion. For assigning of Raman spectra, (Li⁺, K⁺) cation and ([FeCl₄]^?, [SbCl₆]^?) anion substitutions were employed.     

Photoreactivation of RNA in UV-irradiated insect eggs (Smittia sp., Chironomidae, Diptera) II. Evidence for heterogeneous light-dependent repair activities

Abstract. Two biological effects of UV radiation upon Smittia eggs are observed, both of which seem to be associated with the formation of pyrimidine dimers in the RNA (largely ribosomal) of the eggs. While irradiation of the anterior pole region causes the formation of an aberrant segment pattern (double abdomen induction), irradiation of entire eggs leads to an arrest of their development (inactiva-tion). Both UV effects are photoreversible with different action spectra of the photoreactivating light. A dose rate dependence of the photoreactivation can be observed after both UV effects. The saturating dose rate is about 6 W/m² (at 440 nm) after UV induction of double abdomens. Upon UV inactivation, the saturating dose rate level for the photoreactivating light is much higher, and a single light flash causes both a considerable biological reactivation and the disappearance of about 7 × 10⁹ pyrimidine dimers from the total RNA per egg. The results indicate the presence of heterogeneous light-dependent repair activities acting upon UV induced pyrimidine dimers in the RNA of the eggs.     

Equilibria in complexes of N-heterocyclic molecules,part XII. The reaction of hydroxide and alkoxide Ions with platinum(II) complexes of 5-nitro-1,10-phenanthroline and 2,2′-bipyridyl

Summary Bis-(5-nitro-1,10-phenanthroline)platinum(II) dichloride and diperchlorate have been prepared. The reaction between the parent cation and hydroxide ion has been studied using 1 FI n.m.r. spectroscopy and found to involve attack at the ligand. The bis-(2,2-bipyridyl)platinum(II) ion has been shown to be highly reactive towards methoxide ion. The dissociation of a 2,2-bipyridyl ligand is preceded by attack at the ligand.Part XI: R. D. Gillard, t.. A. P. Kane-Maguire and P. A. Williams,Transition Met. Chem., 2, 47 (1977).On leave from the University of Baghdad, Iraq.