C76 fullerene chlorides and cage transformations. Structural and theoretical study

Chlorination of the D(2)-C(76) fullerene under various conditions is studied in detail. It is found that, in addition to the previously known C(76)Cl(18) and C(76)Cl(34), a number of intermediate chlorides are formed, with all molecules falling into two structural types. The first type is observed in the C(76)Cl(18)-C(76)Cl(28) range, whereas further chlorination provides the C(76)Cl(30)-C(76)Cl(34) compounds of the second type exhibiting a major change in the addition motif. We also present a detailed theoretical rationalization of the previously observed skeletal rearrangement in the D(2)-C(76) that affords the non-IPR (18917)C(76)Cl(24) compound.     

Proton-neutron excitations in the high-spin states of 95Tc

The high-spin states of ⁹⁵Tc have been studied in the reaction ⁹³Nb(α, 2n)⁹⁵Tc using inbeam spectroscopy of both γ-rays and conversion electrons. A new sequence of negative-parity states extending up to angular momentum $\text{I =}\text{29}\text{2}$ was found to exist within an excitation energy interval of 4.1 MeV. The positive-parity states are in remarkable agreement with the predictions of a simplified shell-model approach on the basis of coupled excitations of $\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ proton and $\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}{}^{\mathrm{?}}$ as well as $\text{g}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ neutron configurations. A similar analysis for the negative-parity states shows qualitative agreement with the experimental results.     

Isomeric states and rotational structure in the doubly-odd nucleus176Ta

The doubly-odd nucleus¹⁷⁶Ta is investigated by means of in-beamγ-ray spectroscopy techniques using the reactions (α, 3n), (d, 2n) and (p, n). Life-time measurements in thens-region yield low-lying isomeric states withT _1/2=13±1 ns and 30.5±1 ns, while measurements in the ms-region show the existence of a 1.1±0.1 ms isomeric state. A rotational sequence, withK=5 or 6 for the band-head, is also observed.     

Preparation, crystallographic characterization and theoretical study of two isomers of C70(CF3)12

Two isomers of C70(CF3)12 have been isolated from a mixture obtained by trifluoromethylation of C70 with CF3I; their molecular structures determined by X-ray crystallography are in good agreement with the results of theoretical DFT calculations for the most stable C70(CF3)12 isomers.     

Synthesis and crystal structure of rare earth selenates Nd(HSeO4)3, Sm(HSeO4)3, and Nd2(SeO4)3 · 5H2O

Single crystals of rare earth (RE) selenates of the compositions Nd(HSeO₄)₃, Sm(HSeO₄)₃, and Nd₂(SeO₄)₃ · 5H₂O are synthesized and studied by X-ray diffraction analysis at T = 297 and 180 K. It is established that Nd and Sm hydrogen selenates are isostructural to one another and to the corresponding hydrogen sulfates. Neodymium selenate pentahydrate is not isostructural to the analogous RE sulfates, although their structural motifs are similar. __________ Translated from Kristallografiya, Vol. 49, No. 5, 2004, pp. 835–840. Original Russian Text Copyright ? 2004 by Zakharov, Troyanov, Kemnitz.     

New isomers of trifluoromethylated fullerene: C60(CF3)12 and C60(CF3)14

HPLC separation of the products of high-temperature reaction of a sublimed mixture of C₆₀–C₇₀ (10: 1) with CF₃I in a sealed ampoule allowed isolation and determination of molecular structures (X-ray crystallography and ¹⁹F NMR) of two new isomers of C₆₀(CF₃)₁₂ and one isomer of C₆₀(CF₃)₁₄. These isomers are characterized by low relative formation energies, which suggests that the trifluoromethylation process is basically under the thermodynamic control.     

Vibrational analysis study of aluminum trifluoride phases

The vibrational modes of three solid AlF3 phases (alpha, beta, and amorphous high surface area AlF3) are investigated. Calculations have been performed using hybrid exchange correlation functionals to determine the equilibrium geometries and Gamma-point phonon frequencies for the alpha-AlF3 and beta-AlF3 phases. The calculated optical modes are in excellent agreement with experiment. The IR absorption of the amorphous, glasslike high surface area (HS)-AlF3 is also discussed. Deconvolution of the broad envelope of IR stretches and bending vibrations identifies the components of the observed broad band. From the IR vibrational spectrum it has been shown that both short-range and medium-range disorder are present within HS-AlF3. Structural phase transitions are identified by their phase transition temperature Tc, measured by thermal analysis.