TIME-RESOLVED STRUCTURE ANALYSIS OF CRYSTALLINE-STATE REACTION BY A NEW DIFFRACTOMETER DESIGNED FOR RAPID DATA COLLECTION. Yuji Ohashi, Department of Chemistry, Tokyo Institute of Chemistry, Ookayama, Meguro-ku, Tokyo 152, Japan

The structural change of the reactant molecules can be directly observed by stepwise structure analysis using a new diffractometer in the process of the reaction. Since we found that the chiral cyanoethyl group bonded to the cobalt atom in a cobaloxime complex crystal was racemized by X-ray exposure without degradation of the single crystal form[1], many solid-state reactions with retaining the single crystal form, crystalline-state reaction, have been observed[2]. Recently several crystalline-state reactions which proceeds within ten hours have been found[3]. In order to analyze the structural changes in such reactions, we have designed and constructed a new diffractometer for rapid data collection[4]. The diffractometer, which has two imaging plates as detectors, enables us to collect the three-dimensional intensity data within two hours. Several examples of the direct observation of the structural changes by stepwise crystal structure analyses using the diffractometer will be shown and a new crystal chemistry based on the time-resolved structure analysis will be proposed.

[1] Y. Ohashi and Y. Sasada, Nature, 267, 142 (1977)

[2] "Reactivity in Molecular Crystals", Ed. by Y. Ohashi, VCH (1993)

[3] Y. Ohashi et al., Bull. Chem. Soc. Jpn., 68, 2517 (1995)

[4] Y Ohashi and H. Uekusa. J. Mol. Struc.. (1995) in press.