1,2,2,2-Tetrafluor-1-(trifluormethyl)ethylat als Nukleophil und oxydierendes Fluorierungsmittel für 2-Halogen-4,4,5,5-tetrakis(trifluormethyl)-1,3,2-dioxaphospholan

Syntheses and Crystal Structures of the Phases 6R? Cu_xM_1+yS₂ (M = Nb, Ta) Thermal decomposition of 2H? Cu_0.66MS₂ (M = Nb, Ta) results in the formation of 6R? Cu_xM_1+yS₂. Crystals can be obtained by chemical vapour transport reactions with iodine in a temperature gradient (1320–1220 K). The structures of four phases with trigonal symmetry (R3 m, Z = 6) were determined from single crystal x-ray diffraction data. Nb and Ta, resp., of the MS₂ partial structures have a trigonal prismatic coordination. The additional metal atoms are distributed at random only in S-octahedra (Nb, Ta) and -tetrahedra Cu sharing faces with MS₆-prisms. The sequence of the layers can be rationalized on the assumption of stabilizing interactions between metal atoms in adjacent layers.