STRUCTURE ANALYSIS OF TWINNED CRYSTALS OF [Ti18O28H](OBut)17. M.R. Pressprich, R.A. Sparks and C. F. Campana, Siemens Energy and Automation, Inc., 6300 Enterprise Lane, Madison WI 53719-1173, USA; Y.W. Chen, Department of Chemistry, University of Illinois, Urbana, Illinois 61801; and V.W. Day, Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588 USA
A single crystal X-ray diffraction study of the title complex reveals a Ti18O45 metal-oxygen framework having a pentacapped Keggin structure1. The analysis required a deconvolution of the twin components by a version of the Siemens Autoindexing program2, which was modified to obtain reflection indices, orientation matrices and lattice parameters for twinned crystals. Once the orientation matrices were obtained, which indicated the twinning relation of a 2-fold rotation about c*, reflections were grouped into three categories: (1) almost complete overlap of reflections from the two components, (2) partial overlap and (3) no overlap. Reflections from the first and third categories were analyzed with SHELXTL 5.03 to yield the full structure.
1. C.F. Campana, Y.W. Chen, W.G. Klemperer and R.A. Sparks J. Chem. Soc. Dalton Trans, 1996, Issue 1, pp xxv-xxx.
2. Siemens Autoindexing Program; Sparks, R. A. in Crystallographic Computing Techniques; Ahmed, F. R., ed.; Munksgaard; Copenhage, 1976; pp 452-467.
3. SHELXTL PC Operations Manual, Release 5.0; Siemens Industrial Automation, Inc.; Madison, WI, 1994.