ABOUT THE NEW MIXED-VALENT GE7F16 - [GEF6 ](2-) OCTAHEDRA BETWEEN [GE6F10](2- A CONTRIBUTION TO THE STEREOCHEMICAL ACTIVITY OF LONE PAIRS()SHEETS )

For the first time Ge7F16 colourless transparent single crystals have been prepared by the reduction of GeF4 with Ge at 300 degrees C. The e xtremely hygroscopic fluoride crystallizes in a new structure type in Cc with a=1818.0(6) pm, b = 754.3(2) pm, c = 1030.4(3) pm, beta = 90.3 3(3)degrees und Z = 4. Ge7F16 is a mixed valent fluoride according to 6GeF(2)xGeF(4). Characteristical building units of the new structure t ype are [Ge6F10](2+) sheets, which are connected via [GeF6](2-) octahe dra. The Ge2+ within the sheets are coordinated by three nearest F wit h distances of 183-218 pm and together with these form distorted trigo nal pyramids. The structure of Ge7F16 can be considered as a member of the homologues series Gem4+Gen2+F4m+2n with m = 1 and n = 6. Bond ord er summations, band structure calculations and calculations of the Mad elung part of the lattice energy, MAPLE, have been used for the discus sion of the bonding situation.