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

Abstract

Spontaneous disproportionation of lithium biphenyl radical anion into a lithium biphenyl dianion plus neutral biphenyl, according to 2LiBiph ⇄ Li2Biph + Biph, has been evidenced experimentally by UV-vis spectroscopy and backed up theoretically using TDDFT methods.

Characterization of Main Phase in Kxp-Terphenyl and Its Largest Congener Kxpoly(p-phenylene): A Report of Their Magnetic and Electric Properties

“…This spectrum shows a main characteristic band at λ max = 650 nm, in agreement with the reported spectra attributed to p -terphenyl dianion in a solution . To further characterize the compound responsible for this spectrum, we performed a careful time-dependent density functional theory (TDDFT) simulation of the potential species involved, which include both loose and tight ionic pairs of the monoanion, dianion, and trianion of p -terphenyl with solvated potassium as a countercation, as in previous studies . Preliminary results are unequivocal that only the dianion p -terphenyl –2 reproduces the pattern of a main absorption band near the experimental one, which corresponds to a π → π* type of transition.…”

“…19 To further characterize the compound responsible for this spectrum, we performed a careful time-dependent density functional theory (TDDFT) simulation of the potential species involved, which include both loose and tight ionic pairs of the monoanion, dianion, and trianion of p-terphenyl with solvated potassium as a countercation, as in previous studies. 20 Preliminary results are unequivocal that only the dianion p-terphenyl −2 reproduces the pattern of a main absorption band near the experimental one, which corresponds to a π → π* type of transition. Refined calculations, including two potassium ions solvated with DME in the model, fit very well with the experimental spectrum (Figure 6, top).…”

Copolymers of 4‐thieno[3,2‐b]thiophen‐3‐ylbenzonitrile with anthracene and biphenyl; synthesis, characterization, electronic, optical, and thermal properties

“…Optical properties of the polymers were then investigated (Figure 1; Table S1). While the monomer TT‐CN 4 had absorption between 250 and 320 nm (THF) (Figure 1(A)), anthracene had a strong absorption at 250 nm and weak absorptions between 320 and380 nm, 24,25 the third monomer biphenyl displayed a strong absorption between 220 and 280 nm 26,27 . The absorption spectra of the polymers P1 and P2, recorded in THF, had π − π* absorption maxima around 397 and 386 nm and absorption onsets at 450 and 484 nm, respectively, which are quite different than the monomers (Figure 1(A)).…”

“…While the monomer TT-CN 4 had absorption between 250 and 320 nm (THF) (Figure 1(A)), anthracene had a strong absorption at 250 nm and weak absorptions between 320 and380 nm, 24,25 the third monomer biphenyl displayed a strong absorption between 220 and 280 nm. 26,27 The absorption spectra of the polymers P1 and P2, recorded in THF, had π − π* absorption maxima around 397 and 386 nm and absorption onsets at 450 and 484 nm, respectively, which are quite different than the monomers (Figure 1(A)). Although the polymer P1 had a red shift of 25 nm compared to the absorption maximum of P2, the polymer P2 with biphenyl units displayed a stronger absorption band with a higher absorptivity of ε = 13,840 in a wide range of 280-460 nm.…”

Mechanistic and Synthetic Studies of Biaryl Birch Reductions

“…Quenching the reaction mixture with MeOH generated 5 in 57% yield. This quenching protocol produced methoxide, which would reversibly deprotonate the allylic hydrogen to form the more stable compound 3,4-dihydrobiphenyl (11) in 22% yield. The conjugated diene is more prone to reduction, which accounts for the formation of tetrahydro products 12 and 13 in 5% and 1.5% yields, respectively.…”