Delving into the rare-earth metal chemistry of pyrrole-based ligands: Synthesis and analysis of divalent samarium and ytterbium pyrrolide complexes.

The reaction of YbI2(THF)2 with diphenylmethyldipyrrolide leads to a complex reaction from which is obtained an octameric divalent Yb macrocycle (Diphenyldipyrromethanedi-yl-Yb)8 2.1 as a major product, but from which is also isolated a tetrameric cyclic Yb(II)-oxo complex [(diphenyldipyrrolyl-methanedi-yl)Yb]4[(K2)(THF) 6](mu-O)•2(THF) 2.2•2(THF) and a monomeric Yb(III) complex, Yb(diphenyldipyrrolylmethane-di-yl)3(K 3THF3) 2.3, as minor products. Complex 2.1 is analogous to the Sm(II) dipyrrolide octameric clusters obtained under an argon atmosphere, which are thought to represent the intermediate species in the formation of dinitrogen complexes. The reactions of SmI2(THF)2 and YbI2(THF) 2 with the alkali salts of 2,5-dimethylpyrrole, or the reaction of SMCl 3(THF)3 and YbCl3(TBF)3 with the same ligands followed by reduction with the appropriate alkali metals, led to the formation of divalent mono- and polynuclear complexes. (Abstract shortened by UMI.)