CRYSTAL-STRUCTURE OF PBTEF6

PbTeF6 crystallizes with monoclinic symmetry (space group P2(1)/c) and the unit cell parameters a=462.5(1) pm, b=1281.2(2) pm, c=851.9(1) pm , beta=102.36(1)degrees, Z=4. Its crystal structure has been solved by a Rietveld analysis of its X-ray powder pattern and refined to the fi nal agreement factors R(b)=0.059 and R(p)=0.073. The Pb-II and Te-IV a toms are respectively seven- and five-fold coordinated and their lone pair E is stereochemically active. By sharing edges, the PbF(7)E polyh edra constitute infinite zig-zag chains parallel to On. These chains a re connected to each other by sharing their free corners with the TeF( 5)E polyhedra, one of the corners being non-bridging. Structural relat ionships with ReO3-type materials are described and analyzed.