LIMON2 - THE 1ST METALLIC LAYERED NITRIDE

We report the first example of a layered ternary lithium nitride in which the lithium can be deintercalated and reintercalated. The synthesis of LiMoN2 is also the first example of a ternary nitride formed from either the ammonolysis of a molecular organometallic molecule, Li2Mo(NtBu)4 or the ammonolysis of a ternary oxide, Li2MoO4. Elucidation of the unique structure, in a classic illustration, required both synchrotron X-ray and neutron diffraction data. The space group is R3 with lattice parameters (angstrom; from the neutron data) of a = 2.8674 (2) and c = 15.801 (2). The ideal structure consists of MoN2 layers with Mo in trigonal prismatic holes and Li in octahedral holes between the MoN2 layers. The presence of cation anti-site defects was clearly indicated by the joint X-ray/neutron data refinement; the structure is best described as (Li0.85Mo0.15)oct(Mo0.85Li0.15)tpN2. LiMoN2 is Pauli paramagnetic with chi-0 = 0.59 X 10(-6) emu g-1. We have employed a variety of different oxidizing agents for the deintercalation of the lithium from LiMoN2 and have been able to deintercalate up to 64% of the lithium. This deintercalated species can be reintercalated with n-butyllithium at room temperature. In contrast, electrochemical studies show a large hysteresis in the charge/discharge cycles with no reversibility.