Solvent influence on the formation of anhydrous mononuclear or multinuclear lanthanide complexes containing tetradentate Schiff-base ligands

The syntheses, characterization, and crystal structures of six-coordinate mononuclear [bis-5,5ʹ-(1,3-propanediyldiimino)-2,2-dimethyl-4hexene-3-onato]lanthanum [bis(trimethylsilyl)amido][tetrahydrofuran], [bis-5,5ʹ-(1,3-propanediyldiimino)-2,2-dimethyl-4-hexene-3-onato] neodymium [bis(trimethylsilyl)amido][tetrahydrofuran] and the dinuclear species tris[bis-5,5ʹ-(1,3-propanediyldiimino)-2,2-dimethyl-4hexene-3-onato]lanthanum are presented. The complexes are prepared from the reaction of homoleptic tris[(bistrimethylsilyl)amido]lanthanum or -neodymium with the diprotic tetradentate Schiff base bis-5,5ʹ-(1,3-propanediyldiimino)-2,2-dimethyl-4-hexene-3-one and final product nuclearity is controlled through solvent choice: heptane affords only the dinuclear species, despite varied reaction stoichiometries and starting material concentrations, whereas coordinating tetrahydrofuran yields the desired mononuclear complexes. All products are reproducibly isolated in high yields and analytical purity.