Schiff-base -Ate Derivatives with Main Group Metals: Generation of a Tripodal Aluminate Metalloligand

Marta Elena Gonzalez Mosquera, Vanessa Tabernero, Francisco M García-Valle, Jesus Cano, Tomas Cuenca

Index: 10.1039/C8DT00835C

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Abstract

New heterobimetallic aluminates with well-defined structures bearing bidentate Schiff bases as ligands have been prepared. The ligands studied are PhO-CH=N-Ar (Ar = C6H5 (La), 2,6-iPr-C6H3 (Lb)), with and without donor substituents in ortho position of the arene ring bonded to the iminic nitrogen. To prepare the heterometallic species, the proligands HL were treated with the appropriated alkali metal precursor and then AlMe3 was added. In these reactions the alkali metal size has a substantial influence in the outcome. For lithium, the formation of [LiAlMe3(L)]2 1a-b compounds was straightforward and their nuclearity in the solid state was confirmed by an X-Ray study for 1a. When moving to sodium, the analogous species [NaAlMe3(L)]n initially formed, quickly evolves to [NaAlMe2(L)2]n (3a-b) in solution. As well, for potassium, the initial derivatives [MAlMe3L] progress very rapidly to the generation of [KAlMe2L2] as evidenced from the isolation of [KAlMe2(Lb)2] 4b as a crystalline product. Furthermore, for potassium the unique species [KAlMe(Lb)3] 5b was isolated which shows, as a striking feature, the presence of a unusual tripodal metalloligand.