Five-coordinate organoaluminum acetylides and crystal structure of the hydrosylate, [Salophen(tBu)Al]2O

The first examples of five coordinate aluminum acetylide compounds chelated by a single ligand are reported in this paper. The combination of L(tBu)AlCl (where L=Salen (1), Salpen (2), Salophen (3), Salomphen (4)) with LiCCPh in THF at −78 °C leads to the formation of the four acetylides (5–8), LCCPh. These are extremely moisture sensitive and readily hydrolyze to form aluminum hydroxides and with condensation form compounds of formula [L(tBu)Al]2O. The hydrosylate [Salophen(tBu)Al]2O (9) has been structurally characterized.