COMPARISON OF SINGLE CRYSTAL STRUCTURE DETERMINATIONS WITH AREA AND SINGLE POINT DETECTOR DIFFRACTOMETERS Matthew S. Legge and A. Guy Orpen, School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K.

The time required for data collection for single crystals may be cut drastically by use of an area detector diffractometer. Typically 6-15 hours are needed as opposed to several days with a conventional four-circle diffractometer. This study details the quality of results obtained using each method of intensity data acquisition.

A comparison is presented of X-ray structures whose data collections have been made on both three-circle area detector (Siemens SMART) and four-circle (Siemens P4 & R3m/V) diffractometers. Samples for analysis were chosen so as to represent a range of small molecule crystal types. Thus, a strongly diffracting organometallic compound [Ru₂Cp₂(u-CO)(CO){u-(MeO₂C)CC(CO₂Me)CH(CO₂Me)} ]¹, a strongly absorbing crystal [W₂Cp₂(C₈Me₇CH₂)][BPh]² and a typical organic molecule [C₂₇H₃₀O₂]³ were used for the comparisons. In common with other studies involving comparisons of data sets ^4,5, the quality of each structure analyis was evaluated by examining the crystal and intensity data, refinement parameters and also the data collection conditions. Data will also be analysed using a variety of statistical techniques (including normal and half-normal probability plots⁶) on intensity data, coordinate and displacement parameters and uncertainty estimates.

¹P. King, S.A.R. Knox, A. Martin, A.G. Orpen, unpublished work.

²N.G. Connelly, M.S. Legge, B. Metz, unpublished work.

³R.W. Alder, A. Martin, A.G. Orpen, unpublished work.

⁴F. Iwasaki et al. Acta Crystallogr., Sect.B, 1995, 51, 1028.

⁵Pohl, E.; Herbst-Irmer R. et al, Helv. Chim. Acta, 1995, 78, 355.

⁶S.C. Abrahams et al Acta Crystallor., Sect. B, 34, 2981.