350 MHz 1H NMR spectra,dipole moments and preferred conformation of 8,9-epoxy-6,7-dihydro-5H-benzocyclohepten-5-ones

350 MHz ¹H NMR spectra and dipole moments showed that in the preferred conformation of 8,9-epoxy-6,7-dihydro-5H-benzocyclohepten-5-one and its 1,4-dimethoxy derivative the oxirane ring takes a pseudo-axial position.     

Experimental study of proton and neutron spin-flip contributions to the electroexcitation of the J=1 state at Ex=5.846 MeV in Pb

The momentum transfer dependence (q=0.20−0.59 fm⁻¹) of the recently discovered M1 transition from the J^π=1⁺ state at E_x=5.846 MeV to the ground state of ²⁰⁸Pb has been studied with high-resolution inelastic electron scattering. The experimental data are compared to results of RPA calculations which include tensor correlations. The influence of these correlations and of the interference of proton and neutron contributions on the M1 transition will be discussed.     

Observation of a spin-parity 4+ K1(2090)

High statistics data for the reaction K^?p → K^?π⁺n at $\text{11}\text{GeV}\text{c}$ have been obtained in the LASS spectrometer at SLAC. A spherical harmonic moment analysis of the Kπ angular distribution displays evidence for a new K¹ state at $\text{2086}\text{MeV}\text{c}{}^2$ with the spin-parity assignment, J^P = 4⁺.     

The electron spin resonance spectra and structures of some aluminium derivatives of 3,6-di-t-butyl-1,2-benzoquinone

ESR spectra are reported for the aluminium derivatives of the semiquinones which are formed when the compounds Et_nAlCl_3-n (n = 0, 1, or 3) react with 3,6-di-t-butyl-1,2-benzoquinone. The conditions (solvent and other ligands about the metal) are identified under which three different types of spectra can be observed, which are assigned to monodentate non-fluxional, monodentate fluxional, and bidentate structures respectively.     

Thermal decomposition of basic aluminium potassium sulphate. Part I. Stages of decomposition

The stages of thermal decomposition of basic aluminium potassium sulphate were studied with the use of differential thermal analysis (DTA), thermogravimetry (TG), mass spectrometry (MS), IR spectroscopy (IR), and X-ray diffraction phase analysis (XRD). The individual stages of the decomposition were determined and both solid and gaseous products of the dissociation were identified. On the basis of spectrometric data and thermodynamic calculations the possibility of the occurrence of the SO in the gaseous reaction products is discussed.     

The protonation of ortho-methoxy- and hydroxy-benzaldehydes in FSO3H?SbF5?SO2 solution

The protonation of o-methoxy- and o-hydroxy-benzaldehydes in FSO₃H? SbF₅? SO₂ solution was investigated by ¹H NMR spectroscopy. The formation of the Z-carbonyl protonated molecule is explained by intramolecular hydrogen bonding.     

Low-energy excited states in 128I produced by the (p,n) reaction

Gamma spectra produced in the ¹²⁸Te(p, n)¹²⁸I reaction were taken as a function of proton bombarding energy E_p = 2.8 MeV to 5.0 MeV. A level scheme composed of 41 excited states was constructed on the basis of singles γ-spectra and extensive γ-γ coincidence measurements. The coincidence measurements were carried out utilizing a three-parameter Ge(Li)-Ge(Li)-timing system. Upper limits were placed on the lifetime of six levels. The modes of de-excitation of many levels as deduced in the present investigation are significantly different from the results obtained in the (n, γ) reaction. Angular distribution measurements combined with the results from the coincidence counting rates and the population strength of the states by primary transitions in the (n, γ) reaction enabled some spin and parity assignments and tentative assignments for many other levels. The ground state and nine positive-parity states were described in terms of admixed twoquasiparticle multiplets.     

New Peptide Lactones of the Streptogramin Family (Group B). Structures of Virginiamycin S5 and Viridogrisein II

Virginiamycin S₅ and viridogrisein II were isolated by liquid chromatography from the crude antibiotics virginiamycin and viridogrisein, respectively. Their structures were elucidated by amino-acid analysis and mass spectrometry.     

Vibronic coupling in excited charge-transfer states of solid-state charge-transfer complexes

Symmetry properties of CT excited states of some weak donor-acceptor complexes are discussed in the context of vibronic coupling with intermolecular vibrations. The results are applied to the analysis of electroabsorption spectra of anthracene-PMDA.