New developments in the determination of the structure of complex organic molecules

INTRODUCTION There can be no doubt that nowadays determinations of the structure of organic molecules can only be carried out economically, when automatic single crystal diffractometers are used. Such a machine collects more data in a fortnight than a hardworking man in many months. But it is not only the speed and the convenience, but also the inherent accuracy of the measurement which counts. Several diffractometers of different type and construction are available and some laboratories have already gained considerable experience in using them. I do not intend to discuss the different principles; my paper will be restricted to the most general instrument, i.e. to the four-circle diffractometer. This instrument permits the measurement of the full three-dimensional array of reflections with one crystal setting. If desired, the measurements can even be made on an Unoriented crystal. My report will concentrate on our experience with these instruments over the last few years.