New molecular aluminum chloride amides [CI2AINEt2]2and [HCIAINEt2]2and their boranate analogues [(BH4)2AINEt2]2and [H(BH4)AINEt2]2

Abstract

New molecular aluminium chloride amides [CI2AlNEt2]2 and [HClAlNEt2]2 were prepared by salt-elimination reactions from lithium diethylamide and aluminium hydride dichloride diethyletherate or aluminium chloride, respectively. With LiBH4 in n-hexane they form the new boranates [(BH4)2 AlNEt2]2 and [H(BH4)AlNEt2]2. X-ray single crystal structure analyses reveal dimeric molecules with non-planar four-membered Al2N2 rings in the solid state ([Cl2 AlNEt2]2 (1): Pnma, V = 1606.3(2) Å3, Z = 4; [HClAlNEt2]2 (2): Pnma, V = 1453.7(2) Å3, Z = 4; [(BH4)2AlNEt2]2 (3): C2/c, V = 1810.8(2) Å 3 , Z = 4; [H(BH4)AlNEt2]2 (4): Pnma, V = 1540.8(3) Å3, Z = 4). Bond lengths and angles are in the usual range for such compounds and torsion angles within the Al2N2 rings vary from 1° to 14° . The packings of the dimeric molecules in compounds 1, 2, and 4 resemble a distorted hexagonal closest packing. NMR spectra corroborate the molecular structures from the solid state. CVD experiments with [HClAlNEt2]2 (2) as a single-source precursor yield thin aluminium layers. [H(BH4 )AlNEt2]2 (4) is the first structurally characterized hydride tetrahydridoborate compound of aluminium.