Organoaluminates with three terminal phenylethynyl groups and their interactions with alkali metal cations

The synthesis of [K+.THF(2,6-iPr(2)C(6)H(3)N(SiMe3)(C CPhh)(3))-]2 (1), [Na+.THF (2,6-iPr(2)C(6)H(3)N(SiMe3)Al(C=CPh)(3))-]2 (2), and [Li+.dioxane (2,6-iPr(2)C(6)H(3)N(SiMe3)Al(C=CPh)(3))-](2).2dioxane (3) respectively by the reaction of [2,6-iPr(2)C(6)H(3)N(SiMe3)AlCl2](2) (4) with the corresponding phenylethynyl alkali metal salt is reported. In compound I the potassium (2, sodium) interacts with the C=C bonds of four phenylethynyl groups. A further coordination site of the potassium (sodium) is occupied by a THF molecule. Thus, the cation therein acts as a bridging moiety to form the dimer. In compound 3 each of the lithium cations is 2-fold coordinated by phenylethynyl ligands and two dioxane molecules. One of the dioxane molecules in 3 functions as a bridge forming the dimer. The herein described compounds are the first structurally characterized species having three terminal phenylethynyl groups bound to the aluminum atom.