Synthesis, structure, and catalytic activity of an organothorium hydride complex

Treatment of ThCl4(tmeda)2 with 3 equiv of [η5-1,3-(Me3C)2C5H3]K in toluene under reflux gives the tris-Cp chloride complex [η5-1,3-(Me3C)2C5H3]3ThCl (1) in 75% yield. The chlorine atom can be replaced by other groups via metathesis reactions. For example, reaction of 1 with an excess of KH in toluene under reflux affords the hydride complex [η5-1,3-(Me3C)2C5H3]3ThH (2) in 68% yield. Complexes 1 and 2 have been characterized by various spectroscopic techniques, elemental analyses, and X-ray diffraction analyses. Complex 2 is an active catalyst for the polymerization of rac-lactide, leading to the atactic polylactides with high molecular weights and narrow molecular weight distributions.