Magnesium, zinc and aluminium complexes supported by tripodal diaminebis(aryloxido) ligands: synthesis, solid state and solution structure

Abstract

The reactions of the diaminebis(aryloxido) ligand precursors [Me₂NCH₂CH₂N(CH₂-4-R-C₆H₃OH)₂] [R = C(CH₃)₂CH₂C(CH₃)₃, H₂2L¹1; R = CH₃, H₂2L²2] with MgⁿBu₂, ZnEt₂ and AlEt₃ create complexes of general formula [M₂(μ-L-κ⁴O,N,N,O)₂] (M = Mg, 1a for L¹ and 1b for L²; M = Zn, 2a for L¹ and 2b for L²) and [Al₂(μ-L-κ³O,N,N,O)₂Et₂] (3 for L¹) in good yields. Compounds 1a–3 were characterized by NMR spectroscopy and ESI-MS experiments. The definitive molecular structure of 1b·CH₂Cl₂, 2a·H₂O, 2b·CH₂Cl₂ and 3 was provided by a single-crystal analysis and revealed their dimeric nature with an M₂O₂ planar core. The L¹ and L² ligands coordinate as the dianions in a tetradentate/bridging manner in 1b, 2a, 2b and in a tridentate/bridging mode in 3. The NMR spectra showed that the solid state of these compounds is essentially retained in solution.