The dilithium salt [Me3SiNCH2CH2NSiMe3] · Li2(THF)2 decomposes slowly upon heating forming a metastable structure of the crystalline [LiN(SiMe3) · THF]2. The crystal structure of the new form was established by single crystal X-ray diffraction showing a decrease in the a and b parameter values of the unit cell, and an expansion of the c value as compared with the structure obtained at room temperature. The major discrepancies among the known and the metastable crystalline framework are the Li-O bond length and the dihedral angle disposition of the trimethylsilyl groups as regarded to the middle Li-N-Li-N heterocyclobutane ring. Attempts to trap the expected additional lithium imine product were unsuccessful although quenching experiments produced polyethyleneimine.
- Lithium amide
- X-ray crystal structure