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

Homoleptic cobalt and copper phenolate A2[M(OAr)4] compounds: the effect of phenoxide fluorination.

Two series of homoleptic phenolate complexes with fluorinated aryloxide ligands A2[M(OAr)4] with M=Co2+ or Cu2+, OAr-=(OC6F5)- (OArF) or [3,5-OC6H3(CF3)2]- (OAr'), A+=K (18-crown-6)+, Tl+, Ph4P+, Et3HN+, or Me4N+ have been synthesized. Two related complexes with nonfluorinated phenoxide ligands have been synthesized and studied in comparison to the fluorinated aryloxides demonstrating the dramatic structural changes effected by modification of OPh to OAr(F). The compounds [K(18-crown-6)]2[Cu(OArF)4], 1a; [K(18-crown-6)]2[Cu(OAr')4], 1b; [Tl2Cu(OArF)4], 2a; [Tl2Cu(OAr')4], 2b; (Ph4P)2[Cu(OArF)4], 3; (nBu4N)2[Cu(OArF)4], 4; (HEt3N)2[Cu(OArF)4], 5; [K(18-crown-6)]2[Cu2(mu2-OC6H5)2(OC6H5)4], 6; [K(18-crown-6)]2[Co(OArF)4], 7a; [(18-crown-6)]2[Co(OAr')4], 7b; [Tl2Co(OArF)4], 8a; [Tl2Co(OAr')4], 8b; (Me4N)2[Co(OArF)4], 9; [Cp2Co]2[Co(OAr')4], 10; and [(18-crown-6)])[Co2(mu2-OC6H5)2(OC6H5)4], 11, have been characterized with UV-vis and multinuclear NMR spectroscopy and solution magnetic moment studies. Cyclic voltammetry was used to study 1a, 1b, 7a, and 7b. X-ray crystallography was used to characterize 1b, 3, 4, 5, 6, 7a, 7b, 10, and 11. The related [MX4]2- compound (Ph4P)2[Co(OArF)2Cl2], 12, has also been synthesized and characterized spectroscopically, as well as with conductivity and single-crystal X-ray diffraction. Use of fluorinated aryloxides permits synthesis and isolation of the mononuclear, homoleptic phenolate anions in good yield without oligomerized side products. The reaction conditions that result in homoleptic 1a and 7a with OArF upon changing the ligand to OPh result in mu2-OPh bridging phenoxides and the dimeric complexes 6 and 11. The [M(OArF)4]2- and [M(OAr')4]2- anions in 1a, 1b, 3, 4, 5, 7a, 7b, 9, and 10 demonstrate that stable, isolable homoleptic phenolate anions do not need to be coordinatively or sterically saturated and can be achieved by increasing the electronegativity of the ligand