Synthesis and structural characterization of an unusual heptameric aluminum imide and the surface fluorination products of the Al7N7 and Al4C4N4 cores

Reaction of RCN with an excess of AlH3·NMe3 in boiling toluene proceeds with the evolution of trimethylamine and provides an unusual heptameric aluminum imide (RCH2NAlH)7 (R=1-adamantyl) (1). Compound 1 is the second heptameric aluminum imide characterized by structural analysis. Compound 1 reacts with Me3SnF to yield a mixture of partially fluorinated products of average composition (RCH2NAl)7F2.26H4.74 (2). The molecular structures of 1 and 2 show that both have an asymmetric Al7N7 core. Within the core, each aluminum atom binds to three nitrogen atoms in such a way that a cage-like structure is formed. The size dependent influence of the ligands on the AlN core formation is discussed. We also report on a tetrafluoro compound (t-BuNCH2AlF)4 (3) with terminal AlF bonds.