An Unusual Hydride-Bridged Aluminum Complex with a Square-Planar Tetraaluminum Core Stabilized by 2,5-Bis((Dimethylamino)methyl)pyrrole Ligands

The novel hydride-bridged tetranuclear aluminum complex {AlH2[C4H2N(CH2NMe2)2-2,5]AlH3}2 (2) and the related deuterium complex {AlD2[C4H2N(CH2NMe2)2-2,5]AlD3}2 (2-D) have been synthesized by reaction of AlCl2[C4H2N(CH2NMe2)2-2,5] (1) with 2 equiv of LiAlH4 or LiAlD4. The crystal structure of complex 2-D reveals an unusual structure in which the aluminum atoms are in a square-planar arrangement. Reaction of 2 with 2 equiv of H2O in diethyl ether affords the aluminum dihydride complex [C4H2N(CH2NMe2)2-2,5]AlH2 (3).