Structure Analysis of Unstable Crystals using Rapid X-ray Measurement System

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1. Rapid collection of X-ray intensity data is especially important for determining structures of unstable crystal. A new type of X-ray diffractometer (DIP-3000) has been developed with Imaging plate as a two-dimensional detector, a kappa-goniometer and a mu-axis in order to measure diffraction intensities from a single crystal within several hours.2. A performance test and comparison of structures using a four-circle diffractometer indicated that the accuracy of the intensity data taken with our new rapid X-ray measurement system are reliable and the system can work quite satisfactorily as a tool of ordinary crystallography and very useful for unstable crystals. Total time for data collection was about 2 or 3 hours for reach crystals, on the contrast to about 3 or 4 days on the four-circle diffractometer. Although R values are larger by about 0.01 than those of four-circle diffractometer, bond lengths and angles obtained from this equipment and a four-circle diffractometer agree quite well within the estimated standard deviations.3. Using this equipment we could successfully determined the crystal structures of several new metal-carbene complexes whose crystals were very unstable. It is revealed that this equipment is very useful for crystals having a large unit cell. Intensity data could be measured within 7-10 hours, on the contrast to about 10 or 14 days on the four-circle diffractometer.4. Dynamic structural transformations and molecular motion in organic crystals were also investigated using this equipment and the mechanism of thermal rearrangement in 2,4-dinitrophenyl-o-anisidine was revealed.