Additive-free nucleophilic addition of imidazolines and imidazoles to haloacetylenes

Nucleophilic addition of imidazolines to 1-halo-1-alkynes takes place by simple heating in DMF without any additives to give (Z)-N-(1-halo-1-alken-2-yl)imidazolines in good yield and in a highly regio- and stereoselective manner. These reaction conditions are also valid for the similar addition of imidazoles.     

Observation of Exceptionally Low-Lying π-π* Excited States in Oxidized Forms of Quadruple-Decker Phthalocyanine Complexes

Spectroscopic investigations have been performed for the oxidized forms of two quadruple-decker phthalocyanine complexes in order to clarify the electronic structures of multiply stacked π-systems. Up to three-electron-oxidized species were isolated by using phenoxathiin hexachloroantimonate as the oxidant. As the oxidations proceed, the Q-bands in the visible region shift bathochromically along with the clear isosbestic points. The one- and three-electron-oxidized species exhibited typical π-radical signals in the ESR spectra, while the neutral and two-electron oxidized species gave no indication of the presence of π-radicals. The electronic transitions observed for the oxidized species reach even into the so-called fingerprint region in IR spectroscopy (～1000 cm(-1)). With the aid of theoretical calculations, these bands can be assigned to the π-π* transitions. Our results provide new insights into π-electronic systems having exceptionally small MO energy gaps.     

Global asymptotic stability for half-linear differential systems with generalized almost periodic coefficients

The following system considered in this paper:

Global asymptotic stability for half-linear differential systems with generalized almost periodic coefficients

The following system considered in this paper:

$$x' = -\,e(t)x + f(t)\phi_{p^*}(y), \qquad y'= -\,(p-1)g(t)\phi_p(x) - (p-1)h(t)y,$$

where \({p > 1, p^* > 1 (1/p + 1/p^* = 1)}\) and \({\phi_q(z) = |z|^{q-2}z}\) for q = p or q = p ^*. This system is referred to as a half-linear system. The coefficient f(t) is assumed to be bounded, but the coefficients e(t), g(t) and h(t) are not necessarily bounded. Sufficient conditions are obtained for global asymptotic stability of the zero solution. Our results can be applied to not only the case that the signs of f(t) and g(t) change like the periodic function but also the case that f(t) and g(t) irregularly have zeros. Some suitable examples are included to illustrate our results.

     

The epitaxial growth of gallium arsenide using triethylarsine

The thermal decomposition of triethylarsine (TEAs) has been studied. It decomposes at a lower temperature than arsine (AsH₃). The decomposition proceeds via a radical process at a temperature above 700°C. Epitaxial growth using TEAs has been investigated. A gallium arsenide (GaAs) layer with good morphology was obtained, but the layer was found to contain a considerable amount of carbon impurity originating from TEAs. The use of TEAs with 10% AsH₃ or with 20% ammonia (NH₃) apparently improves the quality of GaAs layer. A possible scheme for reducing carbon incorporation is discussed.     

Nucleon transfer in highly mass-asymmetric reaction systems between197au and relatively light projectiles in the energy region below 10 MeV/u

Mechanisms of heavy-ion induced nuclear reactions in mass-asymmetric systems were studied by focusing on the nucleon transfer reaction. Excitation functions and projected mean recoil ranges for the target-like products in³⁷-,¹⁶O-,¹⁴N-, and¹²C-induced reactions on¹⁹⁷Au were measured by means ofγ-ray spectrometry. The energy range studied was near the Coulomb barrier of the systems with incident energies below 10 MeV/u. Nucleon transfer reactions were discussed by distinguishing the products from quasi-elastic transfer (QET) and those from deep inelastic transfer (DIT). The tendency towards equilibration of theN/Z value and the energy damping, which are the characteristic features of DIT, were found in the production of Au isotopes. Observations are consistent with the generally accepted concept that QET takes place along a trajectory near the Coulomb trajectory. QET was made to be connected with the interaction radius and most of the cross section ratios were reproduced well by an extended tunneling model.     

The dipole moments and the structures of chloro- and bromo-crotonolactones

The dipole moments of the isomeric pairs of bromocrotonolactones and of chlorocrotonolactones were measured in benzene solutions at 25° along with those of butyrolactone and crotonolactone. Based on the observed moments of the last two compounds, theoretical calculations were made of the moments of these halocrotonolactones for both - and β-modifications. The comparison between the observed and calculated moments showed definitely that, of the isomeric pair of bromocrotonolactones, one having a greater moment 4·70 D and a lower melting point 57° is the -modification and the other isomer having a moment of 3·86 D and a melting point of 77° is the β-modification. Similarly, -chlorocrotonolactone shows a moment of 4·83 D and melts at 27° while the corresponding β-modification has a moment of 3·57 D and a melting point of 51–52·5°. The result is in good agreement with the conclusion derived from the infra-red absorptions of these compounds and affords an unequivocal evidence in favour of the correctness of the reasoning advanced by Gilman et al., by Whiting, and by Owen and Sultanbawa agains the presumption of Hill and his followers. Thus, the long pending problem on the constitutional formulae of isomeric - and β-halocrotonolactones has been settled.