Thermal Charge Transfer

A charge-transfer complex (CT complex or CTQ is involved in all thermal charge-transfer polymerizations and in most of the photo-induced charge-transfer copolymerizations. Mixing of a donor (D), such as VCZ, with an acceptor, such as tetracyanoethylene (TCNE), immediately produces color [31] due to the formation of a CT complex ... 

In the second half of the twentieth century four experimental techniques were developed to measure Ea the equilibrium, the photon, the beam, and the thermal charge transfer methods [4, 18-29]. In addition to the above reactions observed in the ECD and NIMS, negative ions can be formed in other reactions and complementary energetics and kinetics determined. The ECD and NIMS results have been integrated and compared with data obtained from other studies [4] ... 

By 1967 the kinetic model for nondissociative thermal electron attachment and revised values for the electron affinities of 16 aromatic hydrocarbons and 7 aromatic carbonyl compounds were reported [24-26]. The ECD Ea values were correlated to theoretical calculations, electronegativities, spectroscopic data, and reduction potentials. The majority of these remain the most precise electron affinities for such compounds. Some values are assigned to excited states based on the multistate model of the ECD postulated in the 1990s [27, 28]. The electron affinities of atoms, molecules, and radicals were reviewed in 1966 [24]. The relative Ea of nitrobenzene, CS2, and SO2 were measured by the thermal charge transfer techniques and the Ea of O2 by photodetachment [30-32]. 

In the thermal charge transfer methods the electron affinity of a molecule is determined by bracketing the electron affinity of a test species between that of two species with known electron affinities. When the reaction studied is AB —) + CD AB + CD(—) direct charge transfer, the relative electron affinities... 

From the known concentrations of the molecules and measured ion abundances, the equilibrium constant for the electron transfer reaction can be obtained. Figure 6.11 presents the kinetic data for thermal charge transfer reactions in the ICR determination. The concentrations of the two molecules have a ratio of BQ/ NQ = 1.33. The rate constant for the electron transfer can be obtained from the initial rise of the BQ intensity and the decline of the NQ intensity. This is reported as approximately 6 x 10 10 cc/molecule-s. At about 0.15 s, the ratio becomes... 

Speedy and accurate desktop computers and modern programs such as HYPERCHEM place quantum mechanical calculations within the reach of any experimental chemist. The CURES-EC procedure simulates equilibrium methods of measuring electron affinities by calculating the difference between the optimized forms of the anion and neutral. The READS-TCT determination of charge densities in anion complexes simulates thermal charge transfer experiments. The effect of... 

Hamilton C E, Bierbaum V M and Leone S R 1985 Product vibrational state distributions of thermal energy charge transfer reactions determined by laser-induced fluorescence in a flowing afterglow Ar" + CC -> CC (v= 0-6) + Ar J. Chem. Rhys. 83 2284-92... 

Though thermally stable, rhodium ammines are light sensitive and irradiation of such a complex at the frequency of a ligand-field absorption band causes substitution reactions to occur (Figure 2.47) [97]. The charge-transfer transitions occur at much higher energy, so that redox reactions do not compete. 

Interaction of PCSs with electron acceptors and donors results in molecular complexes with partial or complete charge transfer. In particular, detailed investigations involved charge transfer complexes (CTC) of poly (schiff base), polyazines, products of thermal transformations of PAN and a number of other PCSs129, 238, 241 243, 267. ... 

The products of the thermal transformation of PAN were used for the examination of the effect of stereoregularity of the initial polymer on the CTC properties. At equal transformation degrees, the concentration of complete charge transfer states in a bromine-complexed PCS, obtained on the basis of PAN-c (t e., a polymer with elevated content of isotactic sequences), exceeds by two orders of magnitude this parameter in the polymer obtained on the basis of PAN-r. 

By adding small amounts of H2 to the gas mixture and observing the rate of formation of ArH +, they also estimated the following overall rate constants for charge transfer at thermal ion energies. 

The pulsed source method, despite several limitations, appears to be a very useful technique for studying ion-molecule reactions at thermal energies. Although the studies to have date been limited primarily to simple hydrogen transfer reactions, the technique should also prove useful for studying charge transfer and hydride ion transfer reactions at thermal energies. 

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