STRUCTURAL SYSTEMATICS OF RARE-EARTH COMPLEXES .3. STRUCTURAL CHARACTERIZATION OF LANTHANOID(III) PICRATE HYDRATES - GADOLINIUM PICRATE DODECAHYDRATE - AN X-RAY-INDUCED PHASE MODIFICATION - AND SOME GENERAL-ASPECTS OF THE STRUCTURAL CHEMISTRY OF LANTHANOID PICRATES

In the course of the studies described in Parts I and II, an unusual result was observed in the case of the structure determination of hydrated gadolinium(III) picrate. Midway through data collection, the monoclinic P2(1)/c phase underwent a phase modification (X-ray-induced?) to a similar cell more nearly resembling that of the La --> Pr structure type recorded previously, with no loss of crystal integrity, and with useful data sets being obtained on both forms. Redetermination of the structure with a fresh sample yielded no reproduction of the anomaly. These results are recorded and discussed, together with an overview of the consequences of the data of Parts I-III in relation to those of other literature in the field.