Interaction of electron acceptors with bases. Part 6.–Visible absorption spectra of some solid molecular complexes

Abstract

The visible absorption spectra of the solid molecular complexes of N, N, N ' , "-tetramethylp-phenylenediamine with weak electron acceptors show only a single absorption in the visible region corresponding to an intermolecular charge-transfer transition of a loose " outer " molecular complex, whereas the spectra of complexes with acceptors of relatively high electron affinity suggest that ionization by complete transfer of an electron from the donor to the acceptor molecule has occurred in the ground state.

Electrochemical and Electron Transfer Behavior of o-Chloranil with the Presence of Mg2+ in Acetonitrile

“…The increase in the absorption was attributed to the generation of o-CA *À in Equation 4. The wavelength region is in agreement with the reported results [11,15].…”

Confirmation of the inertness of sulfur hexafluoride toward attack by CF3 and CH3 radicals

“…The charge-transfer (C-T) and electron-transfer reactions between ground-state TMPD and x-acceptors in nonpolar and polar media are well documented. * 1 In nonpolar and polar rigid media, TMPD undergoes two-quantum ionization via the triplet state but this does not depend on the proximity of an acceptor molecule.2•3 Donoi>-acceptor collision is important, however, in fluid solutions; for example, the fluorescence spectrum of TMPD in a hydrocarbon solvent at 20°is progressively weakened by systematic addition of -methylnaphthalene and a new emission band appears at longer wavelength which is assigned to a transient C-T complex on the basis of its lack of structure and its variation with temperature, viscosity, and incident light intensity.3 Flash photolysis of these solutions produces triplet state -methylnaphthalene but no triplet TMPD or TMPD•"1" and the sequence of steps remains obscure. 3 Analogous experiments with dimethylnaphthylamine (donor) and m-dimethylphthalate (acceptor) indicate that C-T emission is appreciable only in nonpolar solvents but that in polar solvents it is absent and the donor-acceptor interaction is one of electron transfer to produce radical-ions.4…”

Reactions of radiation-excited states of tetramethyl-p-phenylenediamine with electron acceptors

“…in nonpolar and polar media are well documented. * 1 In nonpolar and polar rigid media, TMPD undergoes two-quantum ionization via the triplet state but this does not depend on the proximity of an acceptor molecule.2•3 Donoi>-acceptor collision is important, however, in fluid solutions; for example, the fluorescence spectrum of TMPD in a hydrocarbon solvent at 20°is progressively weakened by systematic addition of -methylnaphthalene and a new emission band appears at longer wavelength which is assigned to a transient C-T complex on the basis of its lack of structure and its variation with temperature, viscosity, and incident light intensity.3 Flash photolysis of these solutions produces triplet state -methylnaphthalene but no triplet TMPD or TMPD•"1" and the sequence of steps remains obscure. 3 Analogous experiments with dimethylnaphthylamine (donor) and m-dimethylphthalate (acceptor) indicate that C-T emission is appreciable only in nonpolar solvents but that in polar solvents it is absent and the donor-acceptor interaction is one of electron transfer to produce radical-ions.4…”