Flexible Coordination Mode of a Donor-Functionalized Terphenyl Ligand in Monomeric Cp-Based Lanthanocenes

The synthesis and structural characterization of monomeric Cp-based metallocene compounds of the rare-earth elements samarium, yttrium, and ytterbium of general composition Cp2LnDanip (Danip = 2,6-di-o-anisylphenyl) is reported, featuring a donor-functionalized terphenyl moiety as a coligand. Depending on the size of the rare-earth element employed, different coordination modes of the terphenyl moiety are observed. In the case of the relatively large samarium cation both methoxy groups from the terphenyl ligand symmetrically coordinate to the metal cation. However, when smaller cations (yttrium and ytterbium) are employed, a flexible, asymmetric coordination mode of the terphenyl ligand is found.