Effect of the alkali-metal cation on the bonding mode of 2,5-dimethylpyrrole in divalent samarium and ytterbium complexes

The reactions of SmI2(THF)(2), and YbI2(THF)(2) with the alkali-metal salts of 2,5-dimethylpyrrole, or the reaction of SmCl3(THF)(3) and YbCl3(THF)(3) with the same ligands followed by reduction with the appropriate alkali metals, led to the formation of divalent mono- and polynuclear complexes. Structural analysis of these complexes indicated that the bonding mode adopted by the ligand depends on the nature of the alkali-metal cation retained in the structure.