THERMAL DELIGATION OF MO(6)S(8)L(6) CLUSTER COMPLEXES - EXAFS AND OTHER SPECTROSCOPIC TECHNIQUES SUPPORT RETENTION OF THE MO6S8 CLUSTER UNIT UP TO 500-DEGREES-C

Thermal deligation reactions of N-ligated Mo(6)S(8)L(6) cluster comple xes (L = propylamine, pyrrolidine, and piperidine) have been explored at a variety of temperatures in an attempt to form the Mo6S8 binary Ch evrel phase. Direct heating of the cluster complexes (100-500 degrees C) under dynamic vacuum has led to varying degrees of ligand removal w hile retaining the Mo6S8 cluster unit in amorphous products. Support f or the presence of the cluster unit has been gained by the characteris tic Raman band at 445-450 cm(-1), XPS data, and results of a Mo EXAFS study. Mo-Mo and Mo-S bond distances derived from the fitting of the E XAFS data for the amorphous products are in good agreement with those for crystalline Mo6S8 and Mo(6)S(8)L(6) complexes with well-determined structures. Both XPS and EXAFS show that disproportionation to MoS2 a nd Mo does not occur during deligation below 500 degrees C.