Aluminum substituted boroxine and the intermediate based on N-aryl substituted β-diketiminato ligand: Synthesis, characterization and reactivity studies

The reaction of LAlH₂(L=(Z)-4-[(2,6-diisopropylphenyl)amino]pent-3-en-2-ylidene-2,6-diisopropylaniline) (1) with thiophen-2-ylboronic acid and benzo[b]thiophen-2-ylboronic acid resulted in the boroxine-linked aluminum compounds LAl[0B(2-thiophen)]₂(μ-0) (2) and LAl[0B(2-benzo[b]thiophen)]₂(μ-0) (3), respectively. LAl[0B(2,6-CH₃C₆H₄)OH]₂ (4) was synthesized by the reaction of 1 with 2, 6-dimethylphenylboronic acid. 4 is the intermediate analogue of the reaction to 2 and 3, which we postulated for the formation of 2 and 3. All compounds were characterized by IR, 1H NMR and elemental analysis. Furthermore, compounds 2 and 4 were characterized by singlecrystal X-ray diffraction studies. Compound 2 crystallizes in the triclinic space group P1 while 4 crystallizes in the monoclinic P21/c space group. For the structure of 2, one aluminum atom, two boron atoms, and three oxygen atoms form a six-membered planar AlB203 ring. The central aluminum atom is located in the spirocyclic center where the inorganic AlB203 ring is fused to the organic C₃N₂ part. However, compound 4 consists of the metallic-nonmetallic chain of (H)0-B-0-Al-0-B-0(H) as a backbone.