Aggregation of salts of thianthrene radical cations

Sorgo, M. De; Wasserman, B.; Szwarc, M.

doi:10.1021/j100667a029

Cited by 35 publications

(20 citation statements)

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“…The corresponding values of thianthrene were Eeal -Epa2 x 0.20 V; -A&, = 19.3 kJ/ mol; Kdim%l.l-10 at 256 K and 0.3 V; 28.9 kJ/mol; Kdim%4.IO6 at 233 K respectively. In the case of thianthrene, the order of magnitude of KDim is in good agreement with the spectroscopic results (UV-VIS) by de Sorgo et al [6] after converting the equilibrium constants of the latter investigation into those of a pure dimerization 2 T+' = TP. An estimation of the kinetic parameters of the reversible dimerization (TMOT) with the aid of digital simulations [17] yielded values of kf x 1.10' and k b x l.2.104.…”

Section: Methodssupporting

confidence: 87%

“…Its "thermodynamic" redox potentials are tabulated in the literature [5]. However, a few nonelectrochemical investigations, such as a study of visible absorption and ESR spectra of T/T+' [6] and a X-ray analysis of TMOT+'-salts [7], indicate that the radical cations T+' and T M O Y dimerize in solution. Thus, at low temperatures and high concentrations of T+' new absorption bands at 1=470 and 594 nm were observed which were attributed to a dimer with a sandwich-like structure [6,71.…”

Section: Introductionmentioning

confidence: 99%

“…However, a few nonelectrochemical investigations, such as a study of visible absorption and ESR spectra of T/T+' [6] and a X-ray analysis of TMOT+'-salts [7], indicate that the radical cations T+' and T M O Y dimerize in solution. Thus, at low temperatures and high concentrations of T+' new absorption bands at 1=470 and 594 nm were observed which were attributed to a dimer with a sandwich-like structure [6,71. Moreover, at very low temperatures the ESR-signal Structure 1 Structure of thianthrene (R= H) and 2,3,7,8-tetramethoxythianthrene (R=OCHd Author to whom correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

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Kinetic Studies on Reversible Dimerization of Thianthrene and 2,3,7,8‐Tetramethoxythianthrene Radical Cations

Hübler

Heınze

1998

Ber Bunsenges Phys Chem

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Fast scan voltammetry gives kinetic evidence for the reversible dimerization of the radical cations of thianthrene (T) and 2,3,7,8-tetramethoxythianthrene (TMOT) in acetonitrile. At 256 K an equilibrium constant KD~,,, ~9 0 0 for TMOT ( K D i m 'z I . 1. lo4 for T) and rate constants k+ 1.10' and k,,= l.2.104 were determined. Using the semiempirical PM3 method, the formation of o-bonded dimers is indicated. For the dimerization reaction in acetonitrile, enthalpy values of -79 kJ/mol for T and -56 kJlmol for TMOT respectively were calculated. Despite the folded structure of the neutral T and TMOT systems and their planarization during the radical cation formation, the heterogeneous electron transfer kinetics was found to be very fast in both cases (1.6 cmls; 298 K). The activation enthalpy was determined to be 14 kJ/mol in the case of TMOT. Calculations of the inner-sphere reorganization energy using the Marcus theory produced Aff'(s0) = 4.6 kJ/mol for TMOT and 3.9 kJlmol for T respectively at infinite temperatures. This explains the fast electron transfer kinetics and their low activation enthalpies.

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Section: Methodssupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Kinetic Studies on Reversible Dimerization of Thianthrene and 2,3,7,8‐Tetramethoxythianthrene Radical Cations

Hübler

Heınze

1998

Ber Bunsenges Phys Chem

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“…In contrast, the bands around 370 and 690 nm are absent in dichloromethane solution spectra (Figure 1c). The presence of dimeric species in acetonitrile but not in dichloromethane might be attributed to the neutralization of repulsive forces 17. EPR spectra of salts BZ .…”

Section: Resultsmentioning

confidence: 99%

From Monomers to π Stacks, from Nonconductive to Conductive: Syntheses, Characterization, and Crystal Structures of Benzidine Radical Cations

Chen

Wang

et al. 2012

Chemistry A European J

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Salts that contain radical cations of benzidine (BZ), 3,3',5,5'-tetramethylbenzidine (TMB), 2,2',6,6'-tetraisopropylbenzidine (TPB), and 4,4'-terphenyldiamine (DATP) have been isolated with weakly coordinating anions [Al(OR(F))(4)](-) (OR(F) = OC(CF(3))(3)) or SbF(6)(-). They were prepared by reaction of the respective silver(I) salts with stoichiometric amounts of benzidine or its alkyl-substituted derivatives in CH(2)Cl(2). The salts were characterized by UV absorption and EPR spectroscopy as well as by their single-crystal X-ray structures. Variable-temperature UV/Vis absorption spectra of BZ(·)(+)[Al(OR(F))(4)](-) and TMB(·)(+)[Al(OR(F))(4)](-) in acetonitrile indicate an equilibrium between monomeric free radical cations and a radical-cation dimer. In contrast, the absorption spectrum of TPB(·)(+)SbF(6)(-) in acetonitrile indicates that the oxidation of TPB only resulted in a monomeric radical cation. Single-crystal X-ray diffraction studies show that in the solid state BZ and its methylation derivative (TMB) form radical-cation π dimers upon oxidation, whereas that modified with isopropyl groups (TPB) becomes a monomeric free radical cation. By increasing the chain length, π stacks of π dimers are obtained for the radical cation of DATP. The single-crystal conductivity measurements show that monomerized or π-dimerized radicals (BZ(·)(+), TMB(·)(+), and TPB(·)(+)) are nonconductive, whereas the π-stacked radical (DATP(·)(+)) is conductive. A conduction mechanism between chains through π stacks is proposed.

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“…3.2Å [95]. Solution studies of 18b +• by UV-vis spectroscopy showed the presence of monomer-dimer equilibrium [96,97]. A number of structurally characterized derivatives of 1,4-dithiin 18a +• radical cation is much more limited, with one example of dimer [98] and monomer [99] reported so far.…”

Section: 4-dithiinium Radical Cationmentioning

confidence: 99%