SINGLE CRYSTAL X-RAY DIFFRACTION AT 9K IN AUSTRALIA. Alexander N. Sobolev and Brian N. Figgis, Department of Chemistry, University of Western Australia, Nedlands, Perth 6907, WA, Australia
A four-circle Huber 512 goniometer with a two-stage Displex DE202 cryocooler (APD, Cryogenics Inc.), following the Larsen design1 has been constructed. This is the first such X-ray diffractometer in the southern hemisphere. It is controlled by locally-written Fortran software. The results of a study of a single crystal of Rb[Ru(NH3)6]. 2C1O4 2C1 are presented. [[lambda]]-MoK[[alpha]], ß-filter, 9.4(3)K, [[omega]]/2[[Theta]] data collection, 2[[Theta]]max 100deg., scan speed 2.4deg./min, whole sphere, 17500 reflections. The results obtained are compared with 293K and 92K structural data on same compound. A simple form of disorder is present at low temperature with atomic separations only 0.4Å, less than the resolution of the experiment, but which can be clearly modelled because of the large amount and high accurancy of the data. An analysis of the data in terms of the charge density distribution around the atoms is in progress.
1. Larsen, F.K. (1995). Acta Cryst., B51, 468-482.