On the Nature of Lithium Biphenyl in Ethereal Solvents. A Critical Analysis Unifying DFT Calculations, Physicochemical Data in Solution, and a X-ray Structure

Abstract

The lithium ion is an important type of electrolyte that has technological applications in the manufacture of lithium ion cells; therefore, a better understanding of the nature of its solutions is desirable. When associated to the radical anion of biphenyl in an organic solvent, it forms conducting solutions comparable to strong electrolytes such as lithium perchlorate. We have studied the lithium biphenyl solution in dimethoxyethane using DFT calculations. The nature of these ionic solutions is described in terms of a dynamic equilibrium between different types of ionic associations, the composition of which depends on the solvent and the temperature. The X-ray structure of [Li(+)·4C(5)H(10)O][C(12)H(10)(•-)], a solvent-separated ion pair of lithium biphenyl complexed with tetrahydropyran, is reported. Its main structural characteristics coincide with the calculated one, which we think is the dominant species at room temperature, in agreement with the available physicochemical data.

Intercalated metal–organic frameworks with high electronic conductivity as negative electrode materials for hybrid capacitors

“…2b, inset); in contrast, only one redox couple is observed for the 2,6-Naph (COOLi) 2 electrode at 0.8 V. This suggests that a stepwise twoelectron transfer occurs in the 4,4′-Bph(COOLi) 2 electrode, whereas a concerted two-electron transfer occurs in the 2,6-Naph(COOLi) 2 electrode. Since the formation of one-electron reduced anion radical biphenyl (Bph •− ) 24,25 and two-electron reduced dianion biphenyl (Bph 2− ) 29,30 has been reported in the biphenyl framework, such stepwise behavior observed in the dQ/ dV plot of 4,4′-Bph(COOLi) 2 electrode is assumed to be a redox reaction via the anion radical biphenyl (Bph •− ) and dianion biphenyl (Bph 2− ).…”

“…Although some reports have focused on the iMOF electrode with high-rate capability 18,23 , the high-rate performance at temperatures lower than 0°C and its mechanism of the highrate performance remain to be elucidated. To design an iMOF electrode that provides low resistance and favorable lowtemperature characteristics, we selected a dicarboxylate lithium salt containing a biphenyl (Bph) framework 10,11 based on the following characteristics: (i) stepwise formation of a stable complex with one and two lithium atoms per unit (Li − Bph − and Li 2− Bph 2− , respectively) 24 ; (ii) further stabilization of lithium through coordination with oxygen 24,25 ; and (iii) expectation of a lower reduction potential of the biphenyl dicarboxylate lithium salt than that of the naphthalene because biphenyl exhibits a lower reduction potential than naphthalene (0.45 V vs. Li/Li + for biphenyl compared to 0.51 V vs. Li/Li + for naphthalene) 26 . The electrochemical behavior of this material has already been reported as a preliminary step 23 .…”

Spontaneous disproportionation of lithium biphenyl in solution: a combined experimental and theoretical study

“…The equilibria of such contact ion pairs have been previously discussed. 13 When calculating systems which consist of several separated fragments in terms of single reference approach, like DFT(B3LYP), one should keep in mind the known problem of the appropriate resonance structure description. 24,25 To distinguish resonance structures, one can analyze atomic charges and bond lengths in the biphenyl fragment since these are strongly related to the oxidized state of the latter.…”

“…10 ditions that could not be fully attributed to a single species but rather to an equilibrium of several ionic species including mono and dianions, more or less associated in the form of different ion pairs. 13 Biphenyl has indeed the most negative second reduction potential measured (i.e. giving rise to the dianion) among polycyclic arenes, 14 to the point that it rivals with the alkali metals including lithium itself.…”

Enantioselective catalytic lithiation using a chiral binaphthyl derivative as electron carrier

“…of reaction, the product was obtained in 25% yield with comparable enantiomeric excess ( Table 2, entry 12), so enantiomeric excess does not decrease noticeably with reaction time as would be expected in a kinetic resolution. Furthermore, the structure of the ketone seems to influence in the selectivity of the process, so it should be considered that both steps: (i) the formation of the organolithium intermediate (by two electrontransfer processes from arene dianion) [28][29][30] and (ii) the subsequent nucleophilic addition to the ketone, occurs in close proximity to the chiral arene.…”