Salt Metathesis and Direct Reduction Reactions Leading to Group 3 Metal Complexes with a N,N′-Bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene Ligand and Their Solid-State Structures

We successfully prepared and characterized a wide variety of group 3 metal complexes containing a dianionic or monoanionic glyoxal-based N,N′-bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene (DAD) ligand using a salt metathesis reaction of group 3 metal trichlorides with the dipotassium salt of the DAD ligand or a direct reduction of the DAD ligand with 1:1 mixture of group 3 metal powders and group 3 metal halides. The DAD ligand coordinated to group 3 metal in a σ2-enediamide manner for dimeric complexes of yttrium, ytterbium, and europium complexes, whereas σ2,π-enediamide coordination was observed for the lanthanum complex, due to the different ionic radii of the metal atoms. The reaction of the dipotassium salt of the DAD ligand and ScCl3(thf)3 gave a monomeric scandium complex with the monoanionic DAD ligand.