Nature of the complexes formed by alkali metal halides with phosphine oxides

Reaction of alkali metal halides (MX) with methylenediphosphine oxides and various related compounds in nonaqueous solutions leads to the formation of complex compounds. The compositions, properties, and stabilities of these compounds, which have been studied in detail in acetonitrile, are determined by the nature of the cations and anions of the alkali metal halides. Formation of neutral complexes with the composition [MX · L] and cationic complexes with the composition [ML]⁺ has been established. The most characteristic representative of complexes of the first type is [NaI · L]; in the complexes studied, L=R₂P(O)CH₂P(O)R₂ (R=Bu, BuO, or Ph), Ph₂P(O)CH₂P(O) (OC₂H₅)CH₂P(O)Ph₂ and (p-OCH₃C₆H₄)₂P(O)CH₂P(O)(C₆H₄CF₃-p)₂. Compound [LiL]⁺ is characteristic of complexes of the second type; the compounds containing Ph₃P(O), Ph₂P(O)CH₂P(O)Ph₂, and Ph₂P(O)CH₂P(O)(OC₂H₅)CH₂P(O)Ph₂ as ligands have been studied. Stability constants of the complexes [NaI · L] and [LiL]⁺ have been determined by measuring the dependence of the electrical conductivity of solutions of the alkali metal halides in acetonitrile on the concentration of the ligands. The complex-forming power of phosphine oxides increases with increase in the number of P=O groups. Stabilities of the complexes [NaI · L] with ligands with identical structure decrease with increase in the electronegativity of the substituents on the phosphorus atoms.     

Anisotropy of a hole magnetic polaron in a semimagnetic semiconductor

It is shown that the shape of a hole magnetic polaron in a semimagnetic semiconductor with the sphalerite structure is anisotropic: The polaron is strongly oblate in the direction of its magnetic moment. When the anisotropy of the hole spectrum is taken into account, the properties of the polaron depend on the orientation of its spin with respect to the crystallographic axes. Specifically, the binding energy of the polaron is maximum when the spin is oriented along the [111] axis. Pis’ma Zh. éksp. Teor. Fiz. 63, No. 3, 209–213 (10 February 1996)     

Dispersion of low frequency phonons in the deuterated naphthalene crystal

The dispersion curves of the external and the four lowest internal phonon modes in d₈-naphthalene (C₁₀D₈) crystal have been measured by coherent inelastic neutron scattering for the [010] and [100] directions at 98K and partially at 5K. The results are compared with calculations based on model atom-atom “6-exp” potential with the Kitaigorodski set of parameters for C-C, C-H and H-H interactions.     

Vibronic resonance in spectra of frozen solutions of the C60 fullerene derivatives

This paper reports on a study by site-selective laser spectroscopy of low-temperature broadband fluorescence spectra of N-methyl-2-(3,5-di-tert-butyl-4-hydroxyphenyl)-[C₆₀] fulleropyrrolidine (N-MBHPhFP fullerene) molecules embedded in the crystalline toluene matrix. It has been shown that monochromatic laser excitation in the region of vibrational satellites of the pure electronic absorption band initiates structurization of the emission band of a pure electronic transition, which suggests the existence of a set of impurity centers in the crystalline host matrix. An analysis has been made of the factors accounting for replacement of the wide, inhomogeneously broadened band by a series of narrow bands, with the most essential of them being the weakness of electron-phonon coupling in the impurity center, the absence of electronic excitation transfer between the centers, and the vibronic resonance in the excited state of the set of centers. Vibration frequencies of the N-MBHPhFP fullerene in the excited electronic state have been determined.     

Spectroscopy of Molecular Crystals; A Bibliography for 1978

The 1978 Bibliography continues the series of annual issues of Bibliographies Spectroscopy of Molecular Crystals. The full list of these issues from 1957–1968 may be found in Molecular Crystals and Liquid Crystals, 6, 175, 1969. The issues for 1969, 1970, 197 1, 1972, 1973, 1974, 1975, 1976, and 1977 are published ibid, 14, 329 (1971), 17, 55 (1972), 19, 331 (1973), 26, 87 (1974), 30, 239 (1975), 33, 261 (1976), 39, 259 (1977), 46, 25 (1978) and 54, 59 (1979).     

Exciton—Phonon Luminescence of Perfect and Doped Naphthalene Crystals

The structure of phonon side bands in luminescence spectra of local excitons is investigated both theoretically and experimentally. A gradual transition from a spectrum behaviour peculiar for deep impurity centers (with wide phonon side band) to that peculiar for low temperature intrinsic luminescence (the side band becomes split into several bands corresponding to long wave lattice phonons) is investigated depending on the local exciton level depth. Experimental investigations of deuteronaphthalene solutions are presented.