Anhydrous tetranuclear, dinuclear, and dimeric lanthanide complexes bearing tetradentate Schiff bases

This contribution describes the synthesis and complete characterization of dinuclear (Ln2(SB)3) and rigorously dimeric ([(SB)Ln(N(TMS)2)]2) lanthanide complexes bearing “saturated” tetradentate Schiff bases (SB). The molecular connectivities, nuclearity, and metal ion coordination geometries in these compounds are governed by the interplay of Schiff-base steric requirements, metal ion radius, and reaction conditions (i.e., solvent choice, concentration, and temperature); the impact of these factors will be discussed and emphasized in the context of structural similarities and notable intramolecular interactions within these related compounds. Also presented is a tetranuclear Nd3+ complex exhibiting a ladder arrangement of metal ions and μ-oxo bridges; its formation occurs by the destruction of THF at elevated temperatures. All the compounds presented can be reproducibly synthesized in high yields and analytical purity.