Lithium terphenyl derivatives

FIGURE 22. Solid-state structures of lithium terphenyl derivatives... 

The anionic carbene 131 was isolated and characterized as a lithium adduct. Crystallographically determined molecular parameters of 131 are very similar to those found for the isoelectronic lithium terphenyl derivatives. DFT calculations suggested that 131 exhibited a o-donor strength in between imidazol-2-ylidenes and terphenyl anions. ... 

The organolithium-reagent (5) is itself capable of forming the aryne (9) which can add pentafluorophenyl-lithium. This was found to occur and gave the terphenyl derivatives (10) and (11) in the ratio of 1 9 26>. 

Only a few group 1 and 2 metal derivatives of selenolates have been structurally characterized. They are prepared with the same methods used for the thiolates.155,158 At present there are no crystal structures of lithium terphenyl selenolates. However, the potassium and rubidium salts, which are dimeric, have been structurally characterized.155 They are isomorphous, both to each other and to the closely related thiolate analogues.1533 Currently, there are no reported terphenylselenolates reported for the alkaline-earth metals. 

The exploration of the chemistry of terphenyl derivatives of the group 3 metals is due mainly to Rabe and coworkers [13-18]. The ligands used were of the formula C6H3-2,6-Ar2 (Ar = CeHs, C6H2-2,4,6-Mc3, 1-naphthyl, or 3-MeO-C6H4). The halide complexes 1-3 could readily be obtained by simple salt metathesis from the reaction of the terphenyl lithium with anhydrous metal trichlorides MCI3 (M = Sc or Y) in THF at room temperature [13,14], The yttilum complexes 2 and 3 were isolated in moderate yield (ca. 50%) however, only a low yield of the scandium complex 1 could be obtained, most likely because of C-H bond activation as indicated by NMR spectroscopy. These metatheses reactions did not proceed in aromatic solvents or hexanes probably as a result of the low solubility of the reactants in these media. Complex 1 decomposes slowly in THF solution, while 2 and 3 are considerably more stable. 

The sole heavier alkali metal derivative of a terphenyl ligand is the compound (NaC6H3-2,6-Mes2)2.35 It was synthesized by the reaction of its lithium congener with... 

Fu and co-workers have shown that the l-chloro-boracyclohexa-2,4-diene 97 reacts with 4-phenylpyridine at room temperature to provide the />-terphenyl analog 26 in 76% yield as an early example of a borabenzene-pyridine-type complex (Equation 6). The X-ray structure of 26, discussed in Section 7.14.3, shows the three rings not to be coplanar <1997OM1501>. Exposure of the l-chloro-boracyclohexa-2,4-diene 98 to a stabilized carbene results in formation of the complex 29 in 83% yield as an air- and moisture-sensitive colorless powder (Equation 7), crystals of which were grown from toluene the X-ray structure of 29 has been discussed in Section 7.14.3. The use of bulky lithium bases to deprotonate the bis(amido) or bis(alkoxy)boranes 19 allows for the formation of the dianionic 2,2 -diboratabiphenyl derivatives 20 (X = NHPh, OBn), the solid-state structures of which have been discussed (Equation 8) <2006CJC81>. 

Additives have been developed to improve the cathode cyclability performance of lithium batteries (33). Benzene derivatives (biphenyl and o-terphenyl) and heterocyclic compounds (furan, thiophene, N-methylpyrrole and 3,4-ethylenedioxythiophene), which have lower oxidation potentials than those of electrolyte solvents have been tested. The functional electrolytes used are shown in Figure 2.4. 

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