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New isomers of trifluoromethyl derivatives of [70]fullerene, C70(CF3)12 (one isomer), C70(CF3)14 (three isomers), and C70(CF3)16 (one isomer) were synthesized, chromatographically isolated, and characterized by single-crystal X-ray analysis. Three of the five new isomers were obtained by annealing a mixture of higher trifluoromethyl derivatives (realkylation*). Trifluoromethylation of two individual C70(CF3)12 isomers revealed rearrangements of CF3 groups on the fullerene sphere along with the direct addition to the double bonds. The relative energies of the isomers were calculated using the density functional theory. [ABSTRACT FROM AUTHOR]

The crystal and molecular structures of the fullerene halides C70Br10 · 3C6H2Cl4, C70Cl8.4Br1.6, and C78Cl18 have been determined and refined using single-crystal X-ray diffraction with synchrotron radiation. In the molecular structure of C70 X 10 ( X = Br, Cl), ten X halogen atoms are located in the equatorial region of the molecule and form one 1,2 and nine 1,4 contacts in C6 X 2 hexagons. The structure of the higher fullerene chloride C78Cl18 contains two isomers with symmetry C 2 v , which results in the hexagonal symmetry of the crystal due to disordering. [ABSTRACT FROM AUTHOR]

The crystal and molecular structures of the fullerene halides C70Br10 · 3C6H2Cl4, C70Cl8.4Br1.6, and C78Cl18 have been determined and refined using single-crystal X-ray diffraction with synchrotron radiation. In the molecular structure of C70 X 10 ( X = Br, Cl), ten X halogen atoms are located in the equatorial region of the molecule and form one 1,2 and nine 1,4 contacts in C6 X 2 hexagons. The structure of the higher fullerene chloride C78Cl18 contains two isomers with symmetry C 2 v , which results in the hexagonal symmetry of the crystal due to disordering. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Hydrogen sulfate hydrates K[sub 4]{M[sup II][H(SO[sub 4])[sub 2]][sub 2](H[sub 2]O)[sub 2]}, where M[sup II] = Mn or Zn, are synthesized, and their single-crystal structures are determined by X-ray diffraction. The structural units of the orthorhombic crystals (space group Pccn) are potassium and M[sup II] cations, SO[sup 2-, sub 4] and HSO[sup -, sub 4] anions, and water molecules. Strong (2.52 Å) and moderate-in-strength (2.71-2.75 Å) hydrogen bonds link the anions and water molecules into hexamers. The M[sub II] cations, which have the octahedral environment (Mn-O, 2.14-2.19 Å and Zn-O, 2.07-2.11 Å), link the hexamers into fiat layers. The structures of bimetallic hydrogen chalcogenate hydrates with different compositions are compared. [ABSTRACT FROM AUTHOR]

Three crystalline [N(CH[sub 3])[sub 4]](HSeO[sub 4]) modifications are studied by X-ray diffraction method at 298, 363, and 380 K. The high-temperature phases are characterized by disordering of HSeO[sub 4]-tetrahedra. The systems of hydrogen bonds and the mechanism of the phase transitions are considered. © 2001 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

Abstract: A comprehensive spectroscopic characterization of all known crystalline AlF3 phases (α-, β-, η-, κ-, θ-AlF3) is presented for the first time in this study. Beside their X-ray diffraction powder patterns, which were already published in the literature, 27Al and 19F MAS NMR, FT IR and XPS spectroscopic techniques were applied for all phases in a consistent manner. For all phases prepared the utilization of 27Al satellite transition (SATRAS) NMR allowed to determine the quadrupolar parameters of the aluminium sites including their distributions. In addition, η-AlF3 was isolated with high phase purity and characterized following a new preparation path different from those known so far in the literature. [Copyright &y& Elsevier]