Synthesis and molecular structure of a tetrameric neodymium-silsesquioxane cage complex: {[(i-C4H9)7(Si7O12) Nd]4NaCl}

A new tetrameric neodymium-silsesquioxane cage complex {[(i-C4H9)7(Si7O12)Nd]4NaCl} (1) was prepared by the reaction of NdCl3 with i-PrONa, and subsequent treatment with trisilanol [(i-C4H9)7(Si7O9)(OH)3] in toluene. The molecular structure of the complex was determined by single crystal X-ray diffraction. Preliminary study shows that complex 1 is active for highly cis-1,4 polymerization of isoprene (92% selectivity) in the presence of AlEt3 and Me3SiCl.