THE CRYSTAL-STRUCTURE OF TL3THF7 - A CASE OF STEREOCHEMICAL ACTIVITY OF TL-PAIR IN FLUORIDES( LONE)

The crystal structure of Tl3ThF7 has been solved from single crystal X -ray diffraction data recorded on an automatic four-circle diffractome ter. Tl3ThF7 crystallizes in the monoclinic system with unit cell dime nsions : a = 9.793(1) Angstrom, b = 8.464(5) Angstrom, c = 10.712(1) A ngstrom, beta = 117.20(1)degrees, P2(1)/m (n degrees 11) space group a nd Z = 4. Refinements lead to a conventional R of 0.044 (R(w) = 0.051) for 1748 independent reflections. The 3 D framework of this structure is built from polyhedral Tl+ layers crosslinked by double chains of T h polyhedra and binuclear units constituted of two square pyramids sur rounding Tl+ ions and joined by their apical vertices. This structure delimits cavities towards the center of which the lone pairs of all th allium ions are pointing.