Inhibition of the Cyclotrimerization of Benzonitrile and the Likely Mechanism of the Cyclotrimerization Process:  Structure of a New Tetrameric α-Amino Lithium Imide Demonstrating <i>Intra</i>molecular Stabilization of the Metal Centers

Reaction of ((2-(dimethylamino)ethyl)methylamino)lithium (<b>4</b>) with benzonitrile gives a new α-amino lithium imide, <b>5</b>, which in the solid state is a tetrameric cubane. Aggregation is accompanied by chelation of each metal center using a tertiary amino function, yielding stable seven-membered rings. The stability of <b>5</b> limits cyclotrimerization of the benzonitrile moiety to 2,4,6-triphenyl-1,3,5-triazine, thereby suggesting a likely mechanism for the cyclotrimerization process.