Reaction of 1,3-diols with Al(Bu-t)(3) and Ga(Bu-t)(3): aluminium- and gallium-based bifunctional tetradentate ligands

摘要

Reaction of M(Bu-t)(3) (M=Al, Ga) with neol-H-2 (2,2-dimethylpropane-1,3-diol) yields [M-2(Bu-t)(4)(neol-H)(2)], M=Al (1) and Ga (2), respectively. Use of an equimolar mixture of Al(Bu-t)(3) and Ga(Bu-t)(3) allows for the formation of [AlGa(Bu-t)(4)(neol-H)(2)] (3). Compounds 1 and 2 may be considered as bifunctional (two OH groups), tetradentate (4O) ligands as highlighted by their reactivity with Group 13 hydrides and alkyls. Reaction of compound 1 with AlH3(NMe3), AlH2Cl(NMe3) and AlMe3 yields the tri-aluminium compounds, [Al-3(Bu-t)(4)(X)(neol)(2)] with X=H (4), X=Cl (5), Me (6), respectively. Similarly, compound 2 reacts with Ga(Bu-t)(3) to yield the tri-gallium compound, [Ga-3(Bu-t)(5)(neol)(2)] (7). The mixed metal complexes, [Ga2Al(Bu-t)(4)(X)(neol)(2)], where X=H (8), Me (9) and Bu-t (10), are formed by the reaction of compound 2 with AlH3(NMe3), AlMe3, and Al(Bu-t)(3), respectively. The solid state conformation of the neol backbone and the H-1 NMR chemical shift of the neol's CH2 protons, in compounds 4-10, are both dependent on the steric bulk of the substituent of the central metal. Thermolysis of compound 2 in toluene results in the formation of [Ga-3(Bu-t)(4)(CH2Ph)(neol)(2)] (11), while the reaction of 2 with LiOH in Et2O and hexane yields [Ga3Li4(Bu-t)(6)(neol)(3)(OH)(THF)] (12) and [Ga2Li(Bu-t)(4)(OH)(2)(neol-H)] (13), respectively. The molecular structures of compounds 1, 2, 4-13 and [Ga3Cl5(OSiMe2OSiMe2O)(2)] (14) have been determined by X-ray crystallography. [References: 45]